long-term performance of ornamental perennials

8/8/2019 Long-term performance of ornamental perennials

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EVALUATING THE LONG-TERM PERFORMANCE OF

ORNAMENTAL HERBACEOUS PLANTS USING A

QUESTIONNAIRE-BASED PRACTITIONER SURVEY

Dr.Noel Kingsbury, associate of the Department of Landscape, University of Sheffield

ABSTRACTExtensive knowledge concerning the long-term performance of ornamental

herbaceous plants is widely distributed amongst professional and amateur practitionerson an anecdotal basis. Much of this knowledge is not necessarily included in relevantreference literature.

Using a questionnaire-based survey technique, experienced gardeners wereasked to assess a selection of common ornamental herbaceous perennials for key long-term performance criteria: longevity, type of vegetative spread, competitiveness and

tendency to self-sow. The potential of this methodology for future research in this area isemphasised.

Clear agreement on the assessments of many species was found. Mostperformance criteria put the species mentioned by participants on a gradient, withmarked differences between extremes. A number of issues are raised which are of concern for the cost-effective and sustainable management of public spaces, regardingsome taxa: short-lifespans, aggressive spreading, high levels of self-seeding, slowestablishment.

Key wordsherbaceous perennial, planting design, plant longevity, competition,



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1 INTRODUCTION

1.1 Background

Trees and grass have traditionally provided the essential framework of urban parksworldwide, with high-visibility sites planted with annual bedding. Herbaceous perennialsin particular can seem an attractive additional option, as they can offer a long season of floral interest, the element of seasonal change, and unlike annual bedding with its yearlycosts of planting and removal, considerable savings in maintenance costs. Generallyspeaking, the few herbaceous plants in public spaces were traditionally organised intonarrow borders, but recently there has been much interest in a more extensive use of herbaceous ornamentals in public space (Hitchmough 2004), which has been closelylinked to a style of planting that can be described as ‘naturalistic’ or ‘ecological’. There isnevertheless a continuing use of more conventional planting style. The work of PietOudolf in particular has raised the profile of a use of herbaceous perennials which isdistinctly contemporary but not self-consciously ecological (Kingsbury & Oudolf 2005).

Nevertheless the more extensive use of herbaceous perennials, and indeed anywider use of plant diversity, is limited by the low level of horticultural skills in muchcontemporary landscape management practice (Hitchmough & Thoday 2003). There isalso a reluctance to use herbaceous perennials because of there being little knowledgeof their long-term performance: amongst specifiers such as the landscape designprofession, landscape managers and clients. Knowledge of long-term performance is tobe found amongst horticultural professionals, but it is a knowledge which is morerelevant to private or intensively-managed landscapes, such as private gardens or thegrounds of visitor attractions where there are sufficient budgets (of time or money) tomaintain at a high level (Rice 2006).

It is this problem of lack of knowledge of long-term performance which this studyaims at addressing. A reluctance to use herbaceous perennials on the basis of lack of knowledge regarding their long-term performance is fundamentally a problem of cost-management – specifiers concerned with budgets will be reluctant to specify anythingwhich may either die or become so invasive as to require frequent management. Giventhe resource inputs involved in growing and transporting nursery stock, it is alsoimportant for sustainability that the longevity and performance of herbaceous plants indesigned landscapes is such that these resource inputs are minimised, e.g. by reducingthe need for replacing dead plants after only a few years. Cost-effective, but at the sametime ornamental, functional and bio-diverse herbaceous-based plantings can only bedeveloped if specifiers can assure clients that there will not be negative impacts onmaintenance costs within a few years of installation, and that what they are proposing isseen as a good investment.



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1.2 Aims and objectives of the research

Aims

• To investigate the long-term performance of some common ornamentalherbaceous perennials, and the implications of this for cost-effectiveness plantingdesign

• To trial a methodology enabling knowledge transfer.

Objectives

• The design and evaluation of a questionnaire-based survey to gather data on thelong-term performance of herbaceous plants.

• To provide guidance on the long-term performance of the subject plant taxa.

• To outline the problems and potential of future research on long-term plantperformance and on the use of a questionnaire-based survey in future research.

1.3 Issues of long-term plant performance

1.3.1 Lifespan

Herbaceous plants have long been classified as annuals, biennials and perennials,with the definition given by Griffiths, as “a plant lasting longer than twoyears”(Griffiths,1992, Glossary p.l) being widely accepted. However many perennials arefrequently described as “short-lived” or “long-lived” (Thomas 1976). This failure toaddress a fundamental issue, that of longevity, can be regarded as a serious weaknessin the language used by horticulture professionals. If some species can be described as‘short-lived’ or ‘long-lived’ there is the clear implication that others might be ‘medium-lifespan’, i.e. that there is a gradient of lifespan. Lifespan has been little researched,work done at Weihenstephan in Germany being notable (Hansen and Stahl, 1993).

Horticultural literature, whilst using epiphets to describe lifespan, is almost never preciseabout how many years herbaceous perennials might actually live for. Hitchmough 2003adiscusses longevity, and relates the issue to CSR plant functional groups (Grime 2001),and discusses one important correlation very important for the long-term development of herbaceous plantings, the link between relatively short lifespans and a tendency toproduce plentiful seed.

1.3.2 Vegetative spread and competitiveness

Spread (the potential diameter, or horizontal growth ability of a plant), is a veryuseful piece of information for planning any kind planting. Much horticultural literaturehowever gives little quantitative information; Thomas 1976 for example does, Rice 2006

does not. Hitchmough 2003a usefully discusses some broad categories of the nature of herbaceous spread.

The degree of vegetative spread is clearly related to the degree to which a plantwill cover ground (usually seen as desirable for aesthetic reasons, as well as functional,e.g. weed suppression). ‘Ground cover’ is an essential term describing the functionalaspects of certain species in landscape horticulture (Thoday 2003, MacKenzie 1997).However, in other circumstances too rapid or far-reaching a spread may be seen asproblematic if other varieties in the planting are overwhelmed; the word “invasive” isfrequently used to describe such plants, for example Thomas 1976 uses the word 58



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times in the course of the book.Competition is clearly related to degree of spread, but in ecological science it has

a precise meaning, related to the ability of a plant to succeed at the expense of others,and to be able to effectively utilise high levels of resources more effectively than other (Grime 2001).

Both competition and vegetative spread are closely related to plant morphology,

in particular to the degree and nature of clonality (Herben & Hara 1997, Klimes et al,1997). Despite the importance of these issues to ornamental horticulture there has beenlittle serious work done on relating them to issues of plant selection or management;Kingsbury 2008 attempts to relate morphology to competitiveness and to plant selectionfor ecologically-based planting schemes.

1.3.3 Speed of establishment

Species which are slow to establish, i.e. to begin to increase in size once planted out intheir final positions, are noted by writers on garden plants – the default position beingthat herbaceous plants establish quickly, usually with a substantial increase in size in the

second year after planting; Thomas 1976 draws attention to species being slow or difficult, Gerritsen & Oudolf 2000 refer to plants being “slow-growing” which inhorticultural terms amounts to the same thing. No authors give any quantitative data onspeed of establishment, e.g. by size reached after x number of years, as is done for trees and shrubs in Davis 1987 or for climbers in Davis 1990.

1.3.4 Spread by Self-Seeding

Recruitment through seeding (here referred to as self-seeding) is crucial for herbaceous perennials in the wild, but levels and rates vary enormously from species tospecies (Grime 2001). The same is observed in ornamental plantings. Thomas 1976 andGerritsen & Oudolf 2000 are amongst many garden books which discuss self-seeding as

being partly desirable, but easily problematic, if a species recruits so effectively thatothers are overwhelmed visually or functionally. Self-seeding is seen as desirable in thenew-style naturalistic planting (Kingsbury 1996) even if it was not in conventionalgardens, but it has been very little written about, Pfälzner-Thomsen (1995) is one of thefew who has made any kind of systematic survey; Kingsbury and Oudolf 2005 discuss itbriefly. High levels of variation in rate and effectiveness of self-seeding are noted bypractitioners, but there has been no quantitative or extensive systematic qualitativesurvey.

1.4 The nature of knowledge concerning plant performance

1.4.1 Reference sources

A useful outline of sources of information on plant performance is given inHitchmough 2003b. Most English-language horticultural reference literature makesreference to only the most basic information about plants’ ecological requirements: for light, soil moisture and/or good drainage requirements, hardiness and calcareous or acidsoil preferences. Little information on the issues pertinent to long-term performanceabove is given. What is supplied is inevitably unquantified, unsupported, anecdotal andoften vague. Mentions of longevity, competitiveness and self-seeding are given for somespecies but not others – it is thus not systematically treated.



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‘Profiles’ of genera are frequent in horticultural magazines, aimed largely at a non-professional audience, the ones appearing in the RHS journal ‘The Garden’ and ‘ThePlantsman’ are the most detailed and thorough – they are never comprehensive or systematic however.

The reference material in books and magazines is never attributed or supported bycitation, except in the most informal and unsystematic way. It is generally assumed that

information given is either the result of the author’s direct experience or has beenincluded by the author from existing reference material.

1.4.2 Trials

Formal plant trialling is the only way in which specifiers are able to gainindependent advice on plant performance.

In the UK, the Royal Horticultural Society (RHS) runs trials at its headquarters inWisley, Surrey. Until recently, the only long-term trials carried out were on a list of plants(border carnations, garden pinks, chrysanthemums (garden and under glass), daffodils,dahlias, delphiniums, perpetual flowering carnations, irises and sweet peas) of very littlerelevance to contemporary public (or for that matter private) design practice. Every year,there are ‘invited’ trials for specified taxonomic groups of plants, which can run from oneto three years. Trial grounds are regularly visited by various trials sub-committees whoare responsible for giving awards to outstanding plants, and compiling reports. The

Award of Garden Merit is given for “outstanding excellence for ordinary gardendecoration or use”. (RHS 2008). There is no standard set of protocols in use for theassessment of plants in trials. Plants are compared with each other, with the focus beingon the selection of outstanding taxa which will make better garden plants than other comparable taxa (Hunt, L., personal communication).

In The Netherlands, there are no independent trials, although nurseries conducttheir own trials (Oudolf, P, personal communication).

In the German-speaking countries (Germany, Switzerland, Austria) there is atrialling system based on 17 sites, chosen to represent a range of climatic and soil

conditions; funded and administered by a network of tertiary education institutions.Plants may be pre-trialled for two years, before the start of a formal three year trial(Arbeitskreis Staudensichtung n.d.). Evaluations are carried out using a detailed form(Institut für Stauden und Gehölze 1999).

1.4.3 Communities of knowledge

Published information on plant performance is supplemented by informalexchanges. Professionally this may take the form of more experienced garden staff passing information onto newer recruits – the core of a traditional apprenticeship system.Amongst non-professional gardeners there is an extensive and lively informal exchangeof information – between people brought together by being neighbours, being related, or by friendship. An important part of British horticultural life is that of horticultural societies

– the vast majority of which are locally organised; although relatively few members haveextensive experience. There are however some larger groups with a membership whichincludes many experienced gardeners; the Hardy Plant Society (HPS), is particularlynotable, with some 9,000 members, overwhelmingly amateur but with a very highstandard of horticulture; their focus is largely on herbaceous perennials. The HPS,though a national organisation, also acts as an umbrella for some 45 groups organisedon a regional basis. These groups meet regularly, organise outings to gardens, plant



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fairs and act as a very lively locus for informal information exchange. British non-professional horticulture can therefore be described as including a complex of interlocking communities of knowledge.

Similar bodies and informal networks exist in The Netherlands, Denmark andGermany. The German Gesellschaft der Staudenfreunde (Society of PerennialEnthusiasts) is comparable to the British HPS (Gesellschaft der Staudenfreunde 2010).

2 METHODOLOGY

2.1 Outline of research strategy

Given that there is little systematic primary data on long-term plant performance(over three years) – this being understood as data gathered directly from a reasonablesample of plants using uniform criteria, and that gathering such data from trials involvesa heavy consumption of space and time, it is proposed here that an alternative togathering primary data is to gather secondary data, this being understood as practitioner experience of plant performance. This would be collected by means of a writtenquestionnaire.

The collection of secondary data can be seen as the collection of the anecdotalevidence of plant performance which is exchanged in the communities of knowledgedescribed in 1.4.3 above. It can be assumed that, up to a point, the more contributors of data, the more the descriptive of reality the resulting data is (Kittur et al. 2006).

The aim of this research is to gather secondary data on plant performance from avariety of sources, and present it in a quantifiable form, thus formalising what waspreviously scattered and unquantified. Since, given the extensive communities of knowledge present amongst British amateur gardeners, this data collection an also berepresented as a knowledge transfer from a diversity of private realms to the publicrealm.

2.2 Designing a practitioner questionnaire

A questionnaire was devised which aimed at enabling participating practitioners toevaluate plant performance across four key variables: longevity, vegetative spread,competitiveness and self-sowing. The rationale for these, in particular their relevance tothe issue of cost-effectiveness is as follows:

Longevity.Plant death involves unattractive gaps in planting, and costs in replacing.

Vegetative spreadThis may be a valued aspect of a plant taxon if it serves a function, e.g. ground cover,but may represent a potential problem if growth is so rapid or extensive that surroundingspecies or areas of hard landscaping are covered, and thus require management.

Competitiveness

Similarly, this may be valued e.g. where weed suppression is desired, but inter-speciescompetition in mixed plantings may result in loss of less competitive components of aplanting, with a consequent negative impact on visual appeal and expenditure of management time in limiting growth.

Self-sowing.Where species are short-lived, recruitment through seeding may be seen as desirable.However if large numbers of seedlings compete with other species present in theplanting or which begin to grow in adjacent plantings or in areas of hard landscaping,



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this presents a management problem.

It is suggested that these four factors are largely genetically-determined traits(Kingsbury 2008), although their level of expression may be partly determined byenvironmental factors.

Participants were invited to evaluate the performance of included species by

selecting from a gradient of values.The length of time the respondent had grown the plant was sought, with the

request that only species where the respondent had grown the plant in the same placefor at least five years be included. Five years is somewhat arbitrary, its main value beingthat is a longer period than any trials conducted for herbaceous plants.

Information was also sought on the basic ecological conditions of respondents’gardens. This was not in fact used in data analysis as there were not enough examplesof a range of different garden habitats to make this viable; it may however be a usefulguide for further investigation. Its should be noted however that herbaceous plants havea tendency to be generalists (Crawley 1997), and those widespread in cultivation evenmore so.

The core questions of the questionnaire were:See appendix 1 for the full questionnaire.

LongevityFor each species give a score:1 = very short-lived, rarely more than 3 years2 = short-lived, 3-5 years3 = medium-lived, plants may live 5 years or more, but suddenly disappear 4 = long-lived, plants appear to survive for ever

Vegetative spreadFor each species give a score:1 = not spreading, staying in same place2 = slowly expanding clump3 = strongly expanding clump

4 = spreading through occasional runners5 = spreading strongly through extensive runners6 = discontinuous spread, i.e. spreading outwards but older (1-2 year old) growth dying7 = as above, but vigorously

CompetitivenessFor each species give a score:1 = very readily overwhelmed by neighbours or weeds2 = readily overwhelmed, but with some ability to survive competition3 = moderately robust, with ability to survive competition4 = moderately spreading, ability to suppress or infiltrate neighbours, or resist weed encroachment5 = characteristically aggressively spreading, suppressing or heavily infiltrating neighbours



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Speed of establishmentFor each species give a score:1 = slow, acceptable plant size reached in 3 years or longer after planting2 = moderate, acceptable plant size reached in 2 years after planting3 = fast, acceptable plant size reached in first year after planting

Spread by self-seeding

For each species give a score:(Unless you always dead-head, in which case leave blank).1 = never self-seeds2 = rarely self-seeds, or seedlings rarely reach maturity3 = moderate self-seeding4 = extensive, even nuisance, level of self-seeding

2.3 Selecting species for inclusion

Potential respondents were asked to select plants from a list of 96 taxa, with asuggested minimum of 20 (see appendix 1). These taxa were investigated as part of theauthor’s PhD thesis (Kingsbury 2008), and represent a range of generalist ornamentalherbaceous perennials, all of them regarded as suitable for ‘ecologically-based’ planting

schemes for averagely moist and fertile soils, where maintenance is intended to beminimal. The list includes species of a variety of growth strategies and lifespans.In many cases the taxa in cultivation covers a range of genetic diversity, ranging

from material which is more or less identical to wild ancestors, through horticulturalselections to interspecific hybrids. In order to ensure as much clarity as possible,respondents were asked to specify cultivar names if known.

In addition respondents were invited to add any plants they felt should be included;this was done primarily in order to highlight any species which respondent opinion wouldhighlight as possibly valuable, or at least worthy of further examination for futureresearch.

2.4 Finding respondentsThree broad categories of potential respondent were targeted: amateur gardeners,

professional gardeners and proprietors of small to medium-sized nurseries specialisingin herbaceous plants. The category of ‘professional gardener’ is itself a broad one,including:

1. self-employed professionals who manage several private gardens,2. those responsible for a private garden3. those responsible for a private garden which is open to the public on at least

an occasional basis4. those responsible for a private garden which is open to the public as a visitor

attraction5. managers of public parks.

Early discussions resulted in a decision not to pursue 5. as plant knowledge, of herbaceous perennials in particular, seemed too low to make participation useful.

Potential respondents were targeted through:

1. HPS - Hardy Plant Society 1, appeal in journal, and postal mail-shot to

1The HPS, founded 1957, is an organisation aimed at promoting the growing of hardy perennials, largely

amongst amateurs. It has approximately 9,000 members of whom around 8,500 live in the UK (Feb 2010).All receive the journal ‘The Hardy Plant’.



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secretaries of the 45 local groups who make up the society

2. PGG - Professional Gardeners Guild2, appeal in journal

3. RHS - Royal Horticultural Society3, appeal in journal

4. Nursery - Email-shot to nurseries selected from the RHS Plant Finder .

5. Gardens - Email-shot to gardens open to the public selected from the Good

Gardens Guide 2008 . In every case, where there was a response, garden staff filled in questionnaires.

6. Personal - Personal contact: colleagues and friends of the author active in

horticulture.

7. Lectures - Attendees at public lectures or workshops run by the author who

expressed an interest in participating.

The appeals in journal offered the authors’ address and email. Initial responses byemail invited participants the offer of emailing responses or printing out forms andposting back.

Those who wrote/emailed in requesting to be sent the questionnaire were then senta copy, by mail or email.

3 RESULTS

3.1 Effectiveness of recruiting respondents66 people responded with filled-in questionnaires. Of these two filled in more than

questionnaire, as they gardened in more than one place – each location they gardenedwas treated as a separate response – consequently a total of 70 responses made up the

2The PGG was founded in 1977, and is open to all those professionally involved in managing gardens,

membership currently stands at around 1,000 (Feb.2010). All receive the journal3

The RHS, founded in 1804, is open to all interested in gardening; it is primarily an educational charity. UK

circulation of their journal, ‘The Garden’ is around 326,400 (Feb.2010)



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data set.Of the responses, 38 (out of 70) were received on paper, the remainder being

emailed. Of those who responded on paper, only in 8 cases had all correspondencebeen by paper and postage.

source contacts requests responses % response

HPS 23 13 57%

HPS group 17 10 59%

RHS 18 10 56%

PGG 2 1 50%

nursery 77 35 7 20%

garden 60 27 7 26%

personal 23 23 17 74%

lectures 9 1 11%

TOTAL 154 66 43%

Table 3.1The figures here represent the means of making contact with possible

respondents and the success level of getting responses.Source refers to the various means of making contact with potential respondentsdescribed in 2.4 above.Contacts refers to those who responded to an email-shot of potentialrespondents selected from a directory source or (in the case of ‘personal’) to arequest to a personal contact.Requests refers to the number who requested a copy of the questionnaire, i.e.who answered an item in a journal (HPS, RHS, PGG) or a mail-shot sent to alocal HPS group secretary for circulation within an HPS regional group, or to anannouncement in a lecture or workshop run by the author.Responses refers to those who filled in the questionnaire.% responses refers to the percentage of requests that turned into responses.

Given that this study is funded through a North Sea Regional project, anypotential respondent in a climate zone with parameters broadly outside any of theclimates to be found in the EU North Sea Region was rejected. In practice, this meantgenerally meant maritime west coast climate zones; thus the exclusion of Devon andCornwall, English south coast to Hampshire, peninsulas of Wales, west coast Scoland;the Highlands of Scotland were also excluded.

3.1.1 Category of respondent

Respondents were categorised by level of professional involvement withhorticulture.

Amateur Designer Gardenowner

Gardener Nursery Writer Total



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40 4 2 9 10 1 66

Table 3.1.1Amateur - those who do not make a living from their horticulture; in some caseshowever their specialist knowledge may be world-class.Designer – professional garden/landscape designers actively involved inmanaging their own gardens

Garden owner – owners of gardens who derive an appreciable part of their income from the garden, and who actively work in itGardener – those who work professionally as employeesNursery – owners/proprietors of nurseries, who maintain display gardens or stock bedsWriter – garden media professionals

3.1.2 Overview of taxa discussed by respondents

There is considerable taxonomic diversity to the plant taxa on the list:natural species, cultivars, interspecific hybrids and in some cases, plants of disputed origin. Some taxa distributed commercially under a simple binomial butwhich in fact are hybrids,

The combination of level and number of plant taxa which respondentsspecified varied considerably. A species is only subjected to analysis if there are>10 responses. Amongst these are:

1. Multiple examples of a singly defined taxon, such as a species, cultivar or interspecific hybrid – these present an obvious case for analysis at the taxon level.Species where there are cultivars based on selections from the species are alsoincluded in the species count if numbers are <10.

2. Genera including multiple examples of one taxon and small numbers of representatives of a multiplicity of other closely-related taxa – it is proposed to

separate out the taxon/a with >10 examples for analysis, the remainder beingbundled for analysis together – comparison between a single taxon and a bundleof the remainder may indicate a distinctive character for the one/s most-widelyreported.

3. An alternative treatment where no one cultivar has >10 examples, is to bundleall examples of the genus, the result being relevant only as an indication of theperformance of the genus, ‘genus’ here being understood only as referring to thetaxa in cultivation.

In practice, the following category treatments are applied to cases of 2. and 3.:

Achillea interspecific hybrids and Achillea millefolium cultivars. are treated as twoseparate categories.

Anemone x hybrida 'Honorine Jobert' and 'Japanese anemone ' types of late-flowering Far-Eastern origin other than A. x h 'Honorine Jobert' are treated as twoseparate categories.Brunnera macrophylla and Brunnera macrophylla cultivars are treated as twoseparate categories.Crocosmia ‘Lucifer’ and Crocosmia taxa other than 'Lucifer' are treated as two



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separate categories.Echinacea purpurea and Echinacea hybrids are treated together.Geranium phaeum ‘Samobor’, and G. phaeum cultivars other than 'Samobor' aretreated as two separate categories.Geranium x oxonianum types, are all treated together.Heuchera micrantha and hybrids are all treated together.

Hosta, various taxa, are treated together.Kniphofia, various taxa, are treated together.Monarda hybrids, are treated together.A category of Pulmonaria officinalis cultivars are treated separately to ‘Pulmonaria,all taxa’ for some purposes.Rudbeckia fulgida ‘Goldsturm’ is treated separately to ‘Rudbeckia fulgida, all taxa’for some purposes.

On this basis, a total of 62 species or groups of species/cultivars are produced,where there are >10 examples.

3.2 Summary of results

Data for the 62 taxa or taxonomic groups included in the study are given inappendix 2. Raw data for all responses received is in appendix 3, withrespondent garden condition data in appendix 4.

Here, as summaries, are the means of the responses of the assessments for each performance category and the standard deviation from that mean. A caveatre. the interpretation of the means of assessment of vegetative spread is given in4.3.2.

Explanations for the assessment values are given above in 2.2,

Two headings here cover comments on the taxa responded to:

IdentityIf there is a need to clarify identity or comment on the possible range of

genetic diversity in cultivation, or clarify the origin of hybrids.Notes

Where there is a large disparity in participant responses (generallystandard deviation >1.4) this is discussed, or where further explanation or discussion of data is required.

Acanthus mollis33 responses

LongevityVegetative

SpreadCompetitiveness

Speed of establishment

Spread byself-seeding

Mean 4 2.9 4 2.1 1.7

Standard deviation 0.2 1.4 0.9 0.6 0.9

Identity



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Some in cultivation are A. m. Latifolius Group (Turner 2009). This species is alsooften confused with A. hungaricus (Rice 2006).

Achillea millefolium cvs.12 responses

LongevityVegetativeSpread

Competitiveness



Mean 2.8 2.6 2.7 2.1 1.7

Standard deviation 1.1 0.8 0.8 0.3 1

Achillea interspecific hybrids15 responses


Competitiveness



Mean 2.6 1.9 2.3 2 1


IdentityWidespread confusion over origins and ancestry of many Achillea cultivars,

complex hybridisation, some hybrids of doubtful origin placed under A. millefolium (Rice2006).), itself a very polymorphic species with at least two sub-species within Europe(Tutin 1968).Notes

All achilleas reported to be relatively short-lived, and uncompetitive, althoughexperience appears to vary widely, particularly with longevity. Gerritsen & Oudolf (2000)discuss the unpredictable nature of these plants in the garden, reporting that greatestlongevity occurred on a dry acid sandy soil.

Aconitum napellus , and cvs.16 responses


Competitiveness



Mean 3.9 2.7 3.3 2.2 1.4

Standard deviation 0.3 1.7 1 0.8 0.3

IdentityDivided into 5 sub-species, sometimes regarded as separate species (Tutin

1968). It is not known from which one/s the cultivated stock is derived.Notes

Wide level agreement as being long-lived but much disagreement over level of vegetative spread – a high level of spread (category 6) was only observed by onerespondent (59,60 – two gardens), she also thinks that the plant was wrongly labelled,possibly A.carmichaelii syn. fischeri ).

Alchemilla mollis54 responses



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Competitiveness



Mean 3.9 2.6 3.9 2.4 3.5


Notes Comments indicate that many respondents regard it as too aggressively seedingand too competitive.

Amsonia orientalis11 responses


Competitiveness



Mean 3.5 1.9 2.6 1.6 1.1


Anaphalis triplinervis, and cvs10 responses


Competitiveness



Mean 3.6 2.5 3.0 2.1 1.1


Anemanthele lessoniana (Stipa arundinacea)20 responses


Competitiveness



Mean 3.1 2.2 3.3 2.4 3.4


NotesAt USDA zone 8, the hardiness of this species in northern Europe must be

regarded as questionable, which may account for reduced longevity.

Anemone x hybrida 'Honorine Jobert'19 responses


Competitiveness



Mean 3.7 2.7 3.6 1.7 1.3


'Japanese anemone ' types other than A. x h. 'Honorine Jobert'



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19 responses


Competitiveness



Mean 3.8 3.1 3.5 1.7 1.4


Identity A. hupehensis var. japonica, in C17 Japan. A. x hybrida is A. hupehensis var.

japonica x with A. vitifolia (Jelitto & Schacht 1990).

Aquilegia vulgaris, and cvs.37 responses


Competitiveness



Mean 2.6 1.4 3 2.1 3.6


NotesNoted as being relatively short-lived, although experience varies, with no clear

agreement (see table 3.2.1 - 1), this is possibly due to seedlings replacing the originalplant by germination very close to the (very narrow) crown, as respondent 26 notes“(n)ot really sure how long they live as they self seed to replace originals”. Vegetativespread noted as low, so level of competitiveness may reflect a strong tendency to self-seed, rather than competitiveness as per Grime 2001.

Assessmentof Longevity,Categories

No. of responses

1 8

2 9

3 8

4 12

Table 3.2.1 - 1Frequency of responses for assessmentof longevity for Aquilegia vulgaris



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Artemisia lactiflora, and cvs.11 responses


Competitiveness



Mean 3.7 2.5 3.4 2.3 1.5Standard deviation 0.6 0.5 0.7 0.6 0.9

IdentityLong-established in cultivation, new stock was introduced in the (?)1970s from

China under the name ‘Guizhou group’, reflecting the fact that this is not a cultivar but agroup showing some genetic diversity.

Aruncus dioicus13 responses


Competitiveness



Mean 3.9 2.4 3.7 2 1.5


IdentityKnown to be polymorphic across its very extensive range, but stock in cultivation

appears consistent.

Aster x frikartii ‘Mönch’29 responses


Competitiveness



Mean 3.1 1.8 2.7 1.8 1.1


Identity A. amellus x A. thomsonii . Highly variable, both in terms of genetic and somatic

heritage, plus confusion in the trade with A. x frikartii 'Wunder von Stäfa' andpropagation by seed (Rice 2006).

NotesA popular plant but not noted for being competitive or being quick to establish;

although generally noted as being long-lived, many respondents report a more limited

lifespan. In comments, some respondents notice mollusc damage, which may be acontributory factor to reduced lifespan in some gardens.

Astrantia major and cvs.42 responses


Competitiveness



Mean 3.4 2.3 2.9 1.9 1.9



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NotesSeveral respondents gave data for more than one cultivar, or stated in

comments, that they had different experiences with different species. Given that this is acommon European species, it is highly likely that multiple introductions have resulted in

wide genetic diversity in cultivation.

Baptisia australis21 responses


Competitiveness



Mean 3.7 1.7 2.8 1.5 1.2


Brunnera macrophylla

24 responses


Competitiveness



Mean 3.9 2.6 3.5 2.2 2.6


Brunnera macrophylla cvs.11 responses


Competitiveness



Mean 3.6 2.4 3 2.1 1.1


Campanula latifolia, and cvs.13 responses


Competitiveness



Mean 3.4 2.2 2.9 1.9 1.6

Standard deviation 0.9 1.1 1 0.8 1

Centaurea montana, and cvs.21 responses


Competitiveness



Mean 3.6 3 3.6 2.5 2.5


NotesGenerally reported as being strongly competitive, reports of vegetative spread are



§

very diverse table 3.2.1 -2 – this could reflect two possibilities:1. That there is genetic diversity in the garden population, with some forms staying

as a tight clump and some sending out guerrilla runners. Plants observed by theauthor (Kingsbury 2008) were all tight clumps. Rice 2006 and Jelitto & Schacht1990 report some clonal spread; Gerritsen & Oudolf 2003 and Thomas 1976make no mention of this.

2. That survey participants mistook seedlings for running ramets – the species isreported as self-seeding appreciably, or that the plants habit of collapsing itsstems outwards after flowering, followed by regeneration from the centre(Kingsbury 2008) is mistaken for strong vegetative spread.

Assessment of vegetativespread

No. of responses

1 3

2 5

3 8

4 15 2

6 1

7 1

Table 3.2.1 –2Frequency of responses for assessmentof longevity for Centaurea Montana.

Cephalaria gigantea

24 responses


Competitiveness



Mean 3.6 2.5 3.3 2.1 2.2


Chelone obliqua, and cvs.13 responses


Competitiveness



Mean 3.8 2.7 3.3 2.4 1.4


NotesVegetative spread is reported very differently; since this is a relatively late-

flowering species, the issue of collapsing stems post-flowering (as with Centaureamontana above) being misinterpreted is unlikely to be an issue. Confusion of the threespecies in cultivation (C. glabra, C. lyonii and C. oblqua) is likely, Thomas 1976, notesthat C. obliqua produces running ramets.



§

Crocosmia ‘Lucifer’ 23 responses

LongevityVegetative

Spread

Competitivenes

s

Speed of

establishment

Spread by

self-seeding

Mean 3.9 2.8 3.5 2.1 1.5

Standard deviation 0.3 1 0.7 0.6 0.7

IdentityC. masoniorum x C. paniculata

Crocosmia taxa other than 'Lucifer'49 responses


Competitiveness



Mean 3.4 2.4 2.8 1.9 1.2

Standard deviation 1 1 1.1 0.6 0.6

IdentityOf very varied genetic origin, taxa other than ‘Lucifer’ are seen as shorter-lived and

less competitive. Reports on 24 distinct taxa were received, with comments whichindicated that reliability varies considerably - standard deviation of longevityassessments is high; given that frost-hardiness could be an issue with many cultivars(USDA zones 8-9), this is not surprising.

Several respondents, in comments, also reported deterioration of clumps over time.

Dictamnus albus, and cv.16 responses


Competitiveness



Mean 3.1 1.6 2.4 1.2 1


Echinacea purpurea and hybrids

27 responsesLongevity Vegetative




Mean 2.4 1.5 2 2 1.5


IdentityNaturally variable, cultivars also variable as many raised from seed (Rice 2006).



§

Hybrids may involve E. pallida, and E. paradoxa, (Rice 2008).

Echinops ritro and cvs.24 responses

LongevityVegetative

Spread

Competitivenes

s

Speed of

establishment

Spread by

self-seeding

Mean 3.6 2.4 3.3 2.1 1.6


Euphorbia cyparissias and cvs.

26 responses LongevityVegetativeSpread

Competitiveness



Mean 3.5 4.4 4.3 2.6 1.4


NotesWidely reported as an aggressive spreader, with several respondents commenting

that they regret having it in their gardens, it is instructive to note that the majority of respondents reported “spreading through occasional runners” but with a wide range of other assessments of vegetative spread. There are three possibilities here:

1. The level of spread through guerrilla ramets is noted as being heavily dependent

on the density of surrounding vegetation (Kingsbury 2008) – the more dense theneighbours the fewer the ramets.

2. Spread is dependent on soil type – 3 out of 6 respondents who rated it less thancategory 4 for vegetative spread have heavy soil.

3. Genetic variation.

Euphorbia polychroma and cvs,22 responses


Competitiveness



Mean 3.5 1.7 2.9 1.8 1.5


Filipendula rubra and cvs.11 responses


Competitiveness



Mean 3.8 3.7 3.6 2.2 1.4



§

Standard deviation 0 1.3 0.6 0.5 0.7

Geranium 'Johnson's Blue'30 responses

LongevityVegetative

Spread

Competitivenes

s

Speed of

establishment

Spread by

self-seeding

Mean 3.8 2.4 3.1 2.1 1.2


IdentityG. pratense x G. himalayensehybrid. Precise ancestry uncertain, several similar plants grownunder this name (Rice 2006).

Geranium phaeum, other than 'Samobor'33 responses


Competitiveness



Mean 3.5 2.4 3.1 2.2 2

Standard deviation 0.9 1 0.7 0.6 1

IdentityFlower colour naturally variable. Common central European plant so multiple introduction andhence level of variation probable.

Geranium phaeum 'Samobor'12 responses

LongevityVegetative

Spread

Competitivenes

s

Speed of

establishment

Spread by

self-seeding

Mean 3.9 3 3.7 2.3 3


Geranium pratense and cvs.20 responses


Competitiveness



Mean 3.9 3 3.7 2.3 3


IdentityCommon central European plant so multiple introduction and hence level of

variation probable.

Geranium renardii and cvs.21 responses



§


Competitiveness



Mean 3.3 1.7 2.7 1.8 1.3


Geranium sylvaticum cvs.16 responses


Competitiveness



Mean 4 2.3 3.2 2.2 2.3


IdentityFlower colour naturally variable. Common central European plant so multipleintroduction and hence level of variation probable.

Geranium x oxonianum types25 responses


Competitiveness



Mean 4 3.2 4 2.5 2.8


IdentityExists as a natural hybrid, much of what occurs in cultivation can be regarded as

part of a dynamic hybrid swarm - many cultivars fertile(Rice 2006).Notes

The wide variation reported in self-seeding is most probably explained by

differential levels of fertile seed production by the wide range of crosses present in thisgenetically varied and complex group – essentially G. endressii x G. versicolor (Yeo1995). Author observation for example is that ‘Claridge Druce’ self-seeds considerably,but others grown do not. Given that this is noted as a competitive species, and that it ishighly regarded for recurrent flowering and ground-cover abilities (MacKenzie 1997),data on whether or not particular cultivars are potentially aggressive self-seeders issuggested as being potentially valuable.

Helianthus 'Lemon Queen'27 responses

LongevityVegetative

Spread

Competitivenes

s

Speed of

establishment

Spread by

self-seeding

Mean 4.0 3.3 4.0 2.4 1.1


IdentityH. pauciflorus x H. tuberosus. Natural hybrid, but origin uncertain (Rice 2006).



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Helleborus x hybridus55 responses

LongevityVegetative

Spread

Competitivenes

s

Speed of

establishment

Spread by

self-seeding

Mean 3.8 1.8 3.1 1.8 2.9


IdentityH. orientalis crossed with several other species. Complex genetic background foundedon multiple introductions (Rice 2006).

Heuchera micrantha and hybrids16 responses


Competitiveness



Mean 2.9 2.0 2.9 2.3 1.2


IdentityH. micrantha, H. villosa and H. americana all used in breeding, (Rice 2006).

Notes

The range of experience with longevity may reflect either genetic diversity or theresponse of the plant’s habit of forming ramets which tend to grow out of the ground(Kingsbury 2008) to different soils or management – loss of vigour due to impededrooting into substrates often appears to result. Given the increasing commercialimportance of this genus, it is suggested that future research is needed.

Hosta, various taxa26 responses


Competitiveness



Mean 4.0 2.4 3.2 2.4 1.1


IdentityHighly complex genetic heritage involving many species (Rice 2006) and a long

history of cultivation in Japan.



§

Iris sibirica cvs.21 responses


Competitiveness



Mean 3.9 2.7 3.2 1.9 1.4


IdentityIn cultivation often a hybrid, generally I. sibirica x I. sanguinea.Multiple

introduction also likely (Rice 2006).

Knautia macedonica, and cvs.32 responses

Longevity VegetativeSpread

Competitiveness




IdentityMultiple introductions (Rice 2006).

Kniphofia, various taxa36 responses


Competitiveness



Mean 3.7 2.4 3.3 2 1


IdentityHybridise readily in the wild, many cultivars are seedlings of uncertain origin

(Rice 2006).

Liriope muscari , and cvs.23 responses


Competitiveness



Mean 4.0 2.3 3.1 1.9 1.0


Lunaria rediviva16 responses


Competitiveness



Mean 3.5 1.9 3.1 2.1 2.4




§

Lysimachia clethroides22 responses


Competitiveness



Mean 3.8 3.6 4 2.4 1.2


NotesThe wide range of vegetative spread reported is difficult to explain. There is no

evidence of particularly wide genetic diversity in the European garden population.Respondent comments varied, with some suggesting that it was invasive, others (3responses) that die-back was frequent. Two respondents indicated that they thoughtvigour was reduced in drier soils. There was however reasonable agreement that theplant is moderately competitive.

Lythrum salicaria, and cvs.18 responses


Competitiveness



Mean 3.6 2.8 3 2.3 2.3


NotesA wide range of experience with the level of self-sowing indicates that this may

depend on environmental factors. Author experience with growing the plant in twolocations on similar soil (derived from the Old Red Sandstone formation) suggests thatprolific recruitment through seeding is more likely on a wetter soil.

Macleaya cordata14 responses


Competitiveness




Miscanthus sinensis, cvs.44 responses


Competitiveness





§

Mean 4 2.6 3.5 2.1 1.1


IdentityHighly variable species in the wild. Multiple introduction likely, and long history in

cultivation (Darke 2007).

Monarda hybrids13 responses


Competitiveness



Mean 2.9 3.5 3 2.4 1.1


IdentityM. didyma cultivars or of hybrid origin with M. fistulosa.

Notes

The exceptionally high level of disagreement over the level and character of vegetative spread, together with assessment of competitiveness and longevity indicatethat this group of hybrids responds very differently to different environments andmanagement regimes. There is no indication from the literature to suggest that plants of different genetic origins behave differently, and that all taxa in cultivation produceguerrilla ramets of annual duration (Rice 2006, Kingsbury 2008).

Nepeta x faassenii, and cvs.18 responses


Competitiveness



Mean 3.9 2.8 3.4 2.5 1.5


IdentityN. mussinii x N. netella. Variable, possibly a cross made several times.

Papaver orientale, and cvs.41 responses


Competitiveness



Mean 3.8 2.3 3 2.2 1.2


IdentityHybrid complex : P. orientale, P. bracteatum, P. pseudo-orientale, often seed-

grown so specific and cultivar names may be unreliable (Rice 2006).

Persicaria amplexicaulis and cvs.27 responses



§


Competitiveness



Mean 3.9 3.7 3.9 2.3 1.3


Persicaria bistorta 'Superba'14 responsesLongevityVegetative




Mean 3.9 4.1 4 2.5 1.2


Phlomis russelliana24 responses


Competitiveness




Pulmonaria officinalis, and cvs.19 responses


Competitiveness



Mean 3.4 2.5 2.9 2.1 2.1


Pulmonaria, all taxa42 responses


Competitiveness



Mean 3.4 2.6 2.9 2.2 1.7


Rudbeckia fulgida 'Goldsturm'11 responses


Competitiveness



Mean 3.6 2.7 3.5 2.2 1.5




§

Mean 3.5 1.9 2.7 1.9 2.4


Veronicastrum virginicum all vars.23 responses


Competitiveness



Mean 3.9 2.3 3 2.1 1.3


4DISCUSSION

4.1 Recruitment of participants

source%response

HPS 57%

HPSgroup 59%

RHS 56%

PGG 50%

nursery 20%

gardens 26%

personal 74%

lectures 11%

Table 4.1

For explanation of categories see 2.4 and 3.1.

As shown in table 4.1 the highest percentage response (i.e. returnedquestionnaires) was shown by personal contact, which would be expected. This ishowever not necessarily a replicable response, as it is dependent on the author’sparticular position in the British horticulture community. The level of response of thosewho answered a request place in a journal was 50% or above, those who respondedafter contact through an email-shot, was lower. This can be explained in terms of the



§

psychology of contact – someone contacted directly by email is likely to respondpositively to receipt of a questionnaire, but with a lower level of commitment to actuallyfilling it in.

An additional factor explaining possible reduced response amongst the twoprofessional categories (‘nursery’ and ‘gardens’) is that these represent people with busyworking lives and who consequently have less time or interest in filling in a

questionnaire.Judging ‘quality’ of response is important, as this has a major bearing on the

value of the data gathered. Quality is understood here to mean: accuracy of identificationand accuracy of assessment of the various measures of plant performance described.The fact that only around 1% of the entries had to be rejected because of a clearlyincorrect binomial (i.e. seriously mis-spelt name, or ‘ungrammatical’ in terms of thebinomial system, or non-existent binomial) suggests that the data returned was of highquality.

No attempt was made to categorise age or professional background of participants. However, from covering letters received, and intuitive judgements made onhandwriting and other clues, it is thought that a high proportion were retired and/or elderly; several stated they were over 90. Several covering letters mentioned how much

participants had enjoyed filling in the questionnaire, and that it had made them thinkmore clearly about the plants they grew. Only one negative letter was received – theprospective participant wrote that she found the forms too confusing to use.

Comparing the proportions of the membership of the organisations whereappeals for participants were made revealed that approximately, 0.52% of the HardyPlant Society, 0.2% of the Professional Gardeners Guild and 0.0005% of the RoyalHorticultural Society memberships participated. The very low figure for the RHScompared to the HPS or the PGG, may have been due to the small size of the appealrelative to the rest of the content of the magazine, low readership of the section (news)that the appeal was placed in, or it may reflect the fact that the RHS is now a more‘mass’ organisation, with a smaller proportion of knowledgeable gardeners than formerly.

The use of email greatly reduced the workload involved in printing out copies of

the questionnaire, and reduced postage costs.

4.2 Relations between categories surveyed

SS xxxxxxxx

SE xxxxxxx 0.2567

C xxxxxxxx 0.5433 0.1597

VS xxxxxxxx 0.7913 0.5526 -0.025

L xxxxxxx 0.5103 0.6998 0.2519 -0.05

L VS C SE SS

L = LongevityVS = Vegetative spreadC = CompetitivenessSE = Speed of establishmentSS = Tendency to self-sowTable 4.2Correlations between means of respondent assessment of performance categories of the species surveyed (shown as r s values), using Spearman rank method



§

Vegetative spread is shown to be strongly correlated with competitiveness – whichgiven that vegetative spread is a key factor in a plant’s ability to compete withneighbouring plants (Grime 2001) is not surprising, although as noted in Kingsbury 2008there is a possibility that observer assessments may confuse vegetative spread ascause with competition as effect thus resulting in a circular reference. Longevity is alsonoted as showing a distinct correlation with competitiveness and vegetative spread – this

could be explained by longevity being an expression of effective competitive response(for a discussion of competitive response in annuals see Goldberg and Fleetwood 1987),which itself might be partly the outcome of morphological factors concerning spread.Competitiveness and vegetative spread are also correlated with speed of establishment

– all three factors might be expected to be the outcome of the same physiologicalmechanisms for rapid growth (Grime 2001).

No particular relationship between a tendency to self-sow and longevity is noted –Grime 2001 suggests that there is a trade-off between the two, i.e. between long-livedcompetitors and shorter-lived ruderals which need to partition more resources as seedfor the survival of the species.

4.3 Implications for the use of the plants surveyed in cost-effectivenesspublic space management

4.3.1 Longevity

Echinacea purpurea and hybrids 2.4

Achillea interspecific hybrids 2.6

Aquilegia vulgaris, and cvs. 2.6

Achillea millefolium cvs. 2.8

Heuchera micrantha and hybrids 2.9Monarda hybrids 2.9

Knautia macedonica, and cvs. 3.0

Dictamnus albus, and cv. 3.1

Anemanthele lessoniana 3.1

Aster x frikartii ‘Mönch’ 3.1

Geranium renardii and cvs. 3.3

Pulmonaria, all taxa 3.4

Campanula latifolia, and cvs. 3.4

Crocosmia other than 'Lucifer' 3.4

Astrantia major and cvs. 3.4

Amsonia orientalis 3.5Euphorbia cyparissias and cvs. 3.5

Lunaria rediviva 3.5

Geranium phaeum, other than'Samobor' 3.5

Euphorbia polychroma and cvs, 3.5

Thalictrum aquilegifolium, alll vars 3.5

Echinops ritro and cvs. 3.6

Rudbeckia fulgida, all taxa 3.6

Anaphalis triplinervis, and cvs 3.6

Geranium pratense and cvs. 3.6

Lythrum salicaria, and cvs. 3.6

Centaurea Montana, and cvs. 3.6Cephalaria gigantea 3.6

Brunnera macrophylla cvs. 3.6

Anemone x hybrida 'Honorine Jobert' 3.7

Sedum spectabile, and cvs. 3.7

Baptisia australis 3.7

Kniphofia, various taxa 3.7

Artemisia lactiflora, and cvs. 3.7

Geranium 'Johnson's Blue' 3.8

Papaver orientale, and cvs. 3.8

Chelone obliqua, and cvs. 3.8

Stipa gigantean 3.8Helleborus x hybridus 3.8

Lysimachia clethroides 3.8

Filipendula rubra and cvs. 3.8

Sedum telephium cvs. 3.8

Anemone x hybrida (other than HJ) 3.8

Sedum (Herbstfreude Group)'Herbstfreude' 3.9



§

Brunnera macrophylla 3.9

Veronicastrum virginicum all vars. 3.9

Iris sibirica cvs. 3.9

Alchemilla mollis 3.9

Nepeta x faassenii, and cvs. 3.9

Phlomis russeliana 3.9Crocosmia ‘Lucifer’ 3.9

Persicaria amplexicaulis and cvs. 3.9

Aruncus dioicus 3.9

Macleaya cordata 3.9

Persicaria bistorta 'Superba' 3.9

Aconitum napellus, and cvs. 3.9

Geranium x oxonianum types 4.0

Hosta, various taxa 4.0

Geranium sylvaticum cvs. 4.0

Acanthus mollis 4.0

Liriope muscari, and cvs. 4.0Miscanthus sinensis, cvs. 4.0



§

Table 4.3.1 - 1Species surveyed in order of means of respondents’ assessment of longevity.

It is clear that there are many of the species assessed would appear to bereliably long-lived, and so suitable for cost-effective use.

To summarise the above:1) 6 species, have a mean assessment of 4.0, and would thus appear to be

“bomb-proof” in the words of Bob Brown, a leading commercial grower of perennials (Cotswold Garden Flowers) – i.e. reliably long-lived.

2) 20 species have a mean assessment of 3.8 – 3.9. It is possible thatthese are also reliably long-lived but a small number of cases of deathdue to factors such as predation or extreme abiotic stress.

3) The remainder may possibly show a tendency towards being short-lived.This may be trait-based, or may show that these species are morevulnerable to predation or abiotic stress.

Most problematic for investors in public space are those species whichrespondents found to be relatively short-lived, shown in table 4.3.1 - 2.

Mean of assessmentof longevity

Mean of assessmentof vegetativeSpread

Mean of assessmentof spread byself-seeding

Echinacea purpurea and hybrids 2.4 1.5 1.5

Achillea interspecific hybrids 2.6 1.9 1.0

Aquilegia vulgaris, and cvs. 2.6 1.4 3.6

Achillea millefolium cvs. 2.8 2.6 1.7

Heuchera micrantha and hybrids 2.9 2.0 1.2

Monarda hybrids 2.9 3.5 1.1

Knautia macedonica, and cvs. 3.0 1.8 2.1

Dictamnus albus, and cv. 3.1 1.6 1.0

Anemanthele lessoniana 3.1 2.2 3.4

Aster x frikartii ‘Mönch’ 3.1 1.8 1.1

Geranium renardii and cvs. 3.3 1.7 1.3

Pulmonaria, all taxa 3.4 2.6 1.7

Campanula latifolia, and cvs. 3.4 2.2 1.6

Crocosmia other than 'Lucifer' 3.4 2.4 1.2

Astrantia major and cvs. 3.4 2.3 1.9

Table 4.3.1 - 2.Species indicated as being short-lived (scored as <3.4 on the longevity assessment) withassessments of Vegetative Spread and ‘Spread by Self-seeding’.

In some cases respondent comments, or experience as indicated in thehorticultural literature indicate that short lifespans are not necessarily a trait but the result



§

of mollusc predation, e.g Aster x frikartii ‘Mönch’, lack of hardiness, as in Crocosmiataxa, or Anemanthele lessoniana or a high level of vulnerablility to a variety of problemsowing to a slow rate of establishment as in Dictamnus albus (Gerritsen and Oudolf 2003).

It is noted that vegetative spread of these short-lived species tends to be low;Grime 2001 discusses how short-lived species (i.e. those showing some ruderal

character) might be expected to be short-lived, and not to spread through vegetativeclonal ramet production.

It appears as if some species here, notably Aquilegia vulgaris and Anemanthelelessoniana, offset their tendency to be short-lived by a strong tendency to self-sow. Inpublic space this can be regarded as very positive, if the planting is of an informal or naturalistic aesthetic, and might be regarded as a positive aspect of an ecologicallydynamic and healthy system (Kingsbury 2004). It is suggested that trialling or assessment of many other herbaceous species may indicate others with this trade-off,and therefore show potential for lower-maintenance plantings.

The short lifespans of several taxonomic groups included here suggest thatcaution should be used in their inclusion in public space plantings where longevity of effect is important, this is particularly the case since several of these: Echinacea

purpurea and hybrids Achillea interspecific hybrids Achillea millefolium cvs. Heucheramicrantha and hybrids, are currently very popular in the wholesale nursery trade, withparticularly active breeding programmes.

4.3.2 Vegetative Spread

The use of the measure of vegetative spread used here should be treated withcaution, as the questionnaire asked respondents to categorise plants according tovarious criteria of morphology which underlie effective spread by ramets – thesecategories only form a gradient in a very broad sense – from low to high levels of potential effectiveness of spreading mechanisms. Consequently, a mean figure onlyrepresents a mean of respondents assessments on this gradient, and is not to beunderstood as representing a category.

It should be noted that assessment of vegetative spread was the most ‘disputed’performance measure used here; the mean of the standard deviations for all subjects for vegetative spread was 0.9 (Competitiveness and Spread by self-seeding were 0.7,Longevity and Speed of establishment were 0.6,). This may reflect the subjectivecomponent of visual assessment and/or different plant response in differentenvironments.



§

mean of assessmentof vegetativespread

standarddeviation of assessmentsof vegetativespread

meanassessmentof longevity

Acanthus mollis 2.9 1.4 4.0

Anemone x hybrida (other than HJ) 3.1 1.4 3.8

Centaurea montana, and cvs. 3.0 1.6 3.6

Euphorbia cyparissias and cvs. 4.4 1.4 3.5

Filipendula rubra and cvs. 3.7 1.3 3.8

Geranium x oxonianum types 3.2 1.3 4.0

Lysimachia clethroides 3.6 1.4 3.8

Macleaya cordata 4.3 0.9 3.9

Monarda hybrids 3.5 1.7 2.9

Persicaria amplexicaulis and cvs. 3.7 1.2 3.9

Persicaria bistorta 'Superba' 4.1 0.9 3.9

Phlomis russeliana 3.3 0.7 3.9

mean of standard deviation 1.3

Table 4.3.2 Species where the mean of respondents assessment of vegetativespread is >2.9.

Table 4.3.2 shows species which respondents reported as having characteristicshighly favourable for vegetative spread – in many cases comments are made on howeffective this spread is, and how problematic this may be for garden management. Theproblematic nature of strong vegetative spread is strongly culturally bound, and is linked

to conventional as opposed to naturalistic notions of garden aesthetics (Hitchmough2004).

The mean figure for the standard deviation of assessments of vegetative spread(1.3) is higher than for this measure as a whole (0.9), with a wide range of differentassessments for many species. It is possible that respondents who saw strongvegetative spread as being a potential management problem assessed a plant in ahigher than a respondent who did not; those with more naturalistic gardens may nothave observed higher levels of spread or interpreted mechanisms of spread differently.

It should be noted that all these species have high values for assessment of longevity. In some circumstances the tendency of these species to spread combinedwith longevity may create management problems in controlling unwanted propagules or eliminating the plant when it is no longer required, or of competing too effectively with

less competitive elements of plantings. Comments made be respondents made frequentreferences to this. Monarda hybrids however, given that each ramet is only annual induration, are unlikely to present this problem.

Of these species, only one, Geranium x oxonianum types, was assessed ashaving a relatively high rate of self-seeding (2.8), this, combined with a capactity for effective vegetative spread, may be seen as problematic in some situations.



§

4.3.3 Competitiveness

CompetitivenessLongevity

Echinacea purpurea and hybrids 2.0 2.4

Achillea interspecific hybrids 2.3 2.6

Dictamnus albus, and cv. 2.4 3.1Amsonia orientalis 2.6 3.5

Geranium renardii and cvs. S 2.7 3.3

Aster x frikartii ‘Mönch’ 2.7 3.1

Achillea millefolium cvs. 2.7 2.8

Thalictrum aquilegifolium, alll vars 2.7 3.5

Baptisia australis 2.8 3.7

Knautia macedonica, and cvs. 2.8 3.0

Crocosmia other than 'Lucifer' 2.8 3.4

Campanula latifolia, and cvs. 2.9 3.4

Pulmonaria, all taxa S 2.9 3.4

Euphorbia polychroma and cvs, 2.9 3.5Heuchera micrantha and hybrids S 2.9 2.9

Astrantia major and cvs. S 2.9 3.4

Table 4.3.3 -1. Species where mean of assessment for competition rating <3.Species with mean of longevity assessment <3 are grey-shaded.

Table 4.3.3 -1 lists species which were assessed at a mean of <3, (moderatelyrobust, with ability to survive competition). i.e. their ability to compete is weak, thereforethey are likely to be suppressed by more competitive species in plantings. In somecases, indicated by (S), they are noted as being shade-tolerant (Rice 2006), andtherefore competition is likely to be less of a problem in shade, as shade reduces the

growth of competitive species (Grime 2001).Species which are relatively uncompetitive can be expected to be more likely to

fail in plantings where there is a reduced level of management. This problem iscompounded by several of them having lower levels of longevity, as indicated in table4.3.3 -1.

Mean of Competitiveness

Mean of Longevity

Mean of VegetativeSpread

Lysimachia clethroides 4.0 3.8 3.2

Acanthus mollis 4.0 4.0 2.9

Persicaria bistorta 'Superba' 4.0 3.9 3.7Geranium x oxonianum types 4.0 4.0 3.2

Macleaya cordata 4.2 3.9 4.3

Euphorbia cyparissias and cvs. 4.3 3.5 4.4

Table 4.3.4 –2 Species whose mean of assessment for competitiveness is 4 or greater,in order of increasing mean of assessed competitiveness.

Conversely, there are species (see table 4.3.3 - 2.) whose level of competitiveability was assessed as high, often combined with longevity, which indicates that they



§

are very suitable for use in minimum-maintenance situations, but possibly toocompetitive and difficult to control when combined with less vigorous species. Their mechanism of vegetative spread was rated as highly effective in spreading; using thecategories of clonal spread adopted in Kingsbury 2008, the following is noted -

more open phalanx clump, at least at outer edges, more strongly spreading

Acanthus mollisGeranium x oxonianum types

clump with underground guerrilla ramets:

Euphorbia cyparissias and cvs.Lysimachia clethroidesMacleaya cordataPersicaria bistorta 'Superba'

4.3.4 Speed of Establishment

Mean of speed of establishment

Mean of Longevity

Dictamnus albus, and cv. 1.2 3.1

Baptisia australis 1.5 3.7

Amsonia orientalis 1.6 3.5

Anemone x hybrida 'HonorineJobert' 1.7 3.7

Anemone x hybrida (other

than HJ) 1.7 3.8Geranium renardii and cvs. 1.8 3.3

Helleborus x hybridus 1.8 3.8

Aster x frikartii ‘Mönch’ 1.8 3.1

Euphorbia polychroma andcvs, 1.8 3.5

Liriope muscari, and cvs. 1.9 4.0

Iris sibirica cvs. 1.9 3.9

Astrantia major and cvs. 1.9 3.4

Campanula latifolia, and cvs. 1.9 3.4

Thalictrum aquilegifolium, alllvars 1.9 3.5

Crocosmia other than 'Lucifer' 1.9 3.4

Table 4.3.4 Species where mean of assessed speed of establishment was reported asbeing <2, in order of increasing mean of speed of establishment.

15 of the species studied had a mean speed of establishment <2, i.e. weresomewhat slow to establish; it is suggested that in lower management environmentsthey are more likely to fail, owing to suppression by more vigorous species or weeds.However all are reported as being relatively long-lived, see table 4.3.4. In Kingsbury



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2008, it is suggested that there is a defined group of herbaceous perennials which havea strategy similar to that of cespitose grasses and geophytes, characterised byconsiderable investment in root growth in the earlier period of the plant’s life, consequentslow rate of growth above ground, but with a potential for longevity.

Such species are likely to be unpopular with practitioners wanting or needingquick results, but as a long-term investment they may be a good choice, offering many

years of good performance in return for good management in the earlier years.

4.3.5 Recruitment through seeding

Mean of Spread byself-seeding

Mean of Competitiveness

Geranium phaeum, other than 'Samobor' 2.0 3.5

Knautia macedonica, andcvs. 2.1 2.8

Cephalaria gigantea 2.2 3.3Lythrum salicaria, and cvs. 2.3 3.0

Geranium sylvaticum cvs. 2.3 3.2

Thalictrum aquilegifolium, alllvars 2.4 2.7

Lunaria rediviva 2.4 3.1

Centaurea montana, andcvs. 2.5 3.6

Geranium pratense and cvs. 2.5 3.3

Brunnera macrophylla 2.6 3.5

Geranium x oxonianum types 2.8 4.0

Helleborus x hybridus 2.9 3.1

Anemanthele lessoniana 3.4 3.3

Alchemilla mollis 3.5 3.9

Aquilegia vulgaris, and cvs. 3.6 3.0

Table 4.3.5. Species with mean of assessed spread by self-seeding 2.0 or greater,arranged by order of increasingly high assessed tendency to self-seed.

Since recruitment by seed is a key method of species recruitment in nature, it isperhaps harder to explain why many ornamental species do not produce seedlings ingardens, or only do so rarely, than why some do. Ornamental populations may begenetically unsuited to producing viable seed: by being sterile hybrids or because cross-

pollination between genotypes is essential for formation of viable seed. Manyornamental populations are effectively clonal, as they are propagated by division or other vegetative means – there is however little data on this. Even if there is genetic diversitysufficient to support high levels of viable seed production in the cultivated genepool, thisdiversity is very often absent within the cultivated landscape, as all plants present maybe clonal, or in the case of private gardens, there may only have been one original plant.

Self-seeding was often regarded as a nuisance in traditional horticulturalmanagement, but is seen more positively by contemporary practitioners who regard it aspart of a healthy ecological dynamic and naturalistic aesthetic (Kingsbury and Oudolf



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2005, Pfälzner-Thomsen 1995). Self-seeding can also result in a wider range of colour or other forms in the planted landscape. However, in some circumstances some speciescan self-sow to become a problem, with seedlings out-competing other species in theplanting. This can be a particular problem if species are also notably competitive – ascan be seen from table 4.3.5 , many of the most highly assessed self-seeders arenotably competitive.

5 CONCLUSIONS

Questionnaire methodologyA practitioner questionnaire is indicated as a potentially valuable way of

gathering high-quality data on long-term plant performance. The main issue wouldappear to be in finding potential participants. It is suggested that future work using thismethod address participant recruitment methodology as a priority.

Longevity.This vital trait is best appreciated as a gradient (see table 4.3.1), from inevitably

short-lived species to species with a strong tendency for longevity and the survival of abiotic stress. It is suggested that cost-effective public space management would benefitfrom greater awareness of the issues raised by this gradient, and of greater attention tolongevity as an issue by the nursery trade, researchers and professional plant users.Long-term research in this area is strongly supported.

Certain short-lived taxa are currently very popular in the wholesale nursery trade.Indications here are that they are a poor investment in long-term sustainable publicplantings. It is suggested that ‘short-lived perennial’ may be an important category whichno horticultural classification sufficiently recognises, and a lack of awareness of thiscategory-concept has a deleterious effect on cost-effective and sustainable plant use,and of the credibility of the nursery industry.

The possibility is suggested that the nursery industry is geared towards theproduction of taxa largely for the retail trade rather than for public space, and that manyof these retail-orientated taxa are relatively short-lived. It may be that public space iseffectively a low-priority area for varietal innovation in the industry. This should be seenas a serious short-coming in terms of the ability of public space specifiers to developdesigned plantings which are cost-effective and sustainable.

Effective vegetative spread and competitivenessSome species with high assessments of longevity combined with

competitiveness and high levels of vegetative spread may cause ‘weed’ problems insome circumstances owing to the effective distribution of ramets, resulting in increasedmanagement problems – on the other hand this vigorous spread and competitivenessmay be seen as highly desirable in some situations. Further research and greater awareness of these issues, covering a wider range of strongly-spreading species wouldbe useful, in order to provide better specification. See table 4.3.2 for the taxa with thehighest assessments for vegetative spread and table 4.3.4 –2 for the highestassessments of competitiveness.

Conversely, the low level of competitiveness shown by some species (see table4.3.3 –1) is an indication that they may be readily overwhelmed by more vigorousspecies in some plantings where they would be a poor investment.



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Establishment.It is indicated that perennials establish at different rates, and that some species

which are slow to establish may nevertheless be valuable long-lived components of planting, these are listed in table 4.3.4. More knowledge concerning this issue wouldhelp specifiers and managers to safeguard investments made using these taxa.

Self-sowing.This may be valuable in some circumstances, but undesirable in others, table

4.3.5 lists taxa where high levels of seeding are noted. Greater awareness of this issuemay help specifiers to design plantings for appropriate management levels.

6 APPENDICES

Appendix 1 – QuestionnaireSee file Questionnaire v2.doc. In e-version this follows at the end, but pleasenote that owing to software problems not in original format

Appendix 2 – Raw data of taxa and taxonomic groups included for studySee Raw Data - spp. studied.xlsAppendix 3 – All raw data.See Raw data - all .xlsAppendix 4 – Respondent data suppliedSee Respondent data.xls

2-3 not supplied in e-version

7 REFERENCES

Arbeitskreis Staudensichtung (no date). Staudensichtung. Forschungsanstalt für

Gartenbau, Weihenstephan. Available at < www.staudensichtung.de>Viewed 25.Mar.2010.

Crawley, M.J. (1997) The Structure of Plant Communities. In Crawley, M.J. (ed.)Plant Ecology , pp.239-261. Blackwell, Oxford.

Darke, R. (2007). The Encyclopedia of Grasses for Livable Landscapes. Timber Press, Portland, OR.

Davis, B. (1987). The Gardener’s Illustrated Encyclopedia of Trees and Shrubs.Viking, London.

Davis, B. (1990). The Gardener’s Illustrated Encyclopedia of Climbers and Wall Shrubs. Viking, London.

Dosmann, M. (1999). Genes in the landscape. The Horticulturalist, 8:4.

Gerritsen, H. & Oudolf, P. (2000). Dream Plants for Planting the Natural Garden.Timber Press, Portland, OR.

http://www.staudensichtung.de/

http://www.staudensichtung.de/



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Gerritsen, H. & Oudolf, P. (2003). Planting the Natural Garden. Timber Press,Portland, OR.

Gesellschaft der Staudenfreunde (2010). Available at www.gds-staudenfreunde.de. Viewed 12.March,2010.

Goldberg, D.E. & Fleetwood, L. (1987). ‘Competitive effect and response in four annual plants’, Journal of Ecology, 75, pp.113-143.

Griffiths, M. (1992) The Royal Horticultural Society Index of Garden Plants.Macmillan , London.

Grime, J.P. (2001) Plant Strategies, Vegetation Processes and EcosystemProperties. John Wiley, Chichester, UK.

Hansen, R. and Stahl, F. (1993) Perennials and their Garden Habitats, CambridgeUniversity Press, Cambridge

Herben, T. & Hara, T. (1997). ‘Competition and spatial dynamics of clonal plants’, inde Kroon, H. & van Groenendael, J. (eds.) The Ecology and Evolution of Clonal Plants, Backhuys, Leiden.

Hitchmough, J. (2003a). ‘Herbaceous Perennials’. In Hitchmough, J. &Fieldhouse, K. (eds), Plant User Handbook, A guide to effective specifying,Blackwell, Oxford.

Hitchmough, J. (2003b). ‘Selecting Plant Species, Cultivars and Nursery Products.In Hitchmough, J. & Fieldhouse, K. (eds), Plant User Handbook, A guide toeffective specifying, Blackwell, Oxford.

Hitchmough, J. (2004). ‘Naturalistic herbaceous vegetation for urban landscapes’,in The Dynamic Landscape, Design, Ecology and Management of Naturalistic Urban Planting , Dunnett, N, Hitchmough, J. (eds.), Spon Press,London.

Hitchmough, J. & Thoday, P. (2003). ‘Introduction to Plant Use and theLandscape’, in Hitchmough, J. & Fieldhouse, K. (eds), Plant User Handbook, A guide to effective specifying, Blackwell, Oxford.

Institut für Stauden und Gehölze (1999). Staudenneuheiten – Prüfung. Institut für Stauden und Gehölze, Weihenstephan.

Jelitto, L. & Schacht, W. (1990). Hardy Herbaceous Perennials. Timber Press,Portland.

Kingsbury, N. (1996) The New Perennial Garden. Frances Lincoln, London.

Kingsbury, N. (2004). ‘Contemporary overview of naturalistic planting design’, , inThe Dynamic Landscape, Design, Ecology and Management of Naturalistic Urban Planting , Dunnett, N, Hitchmough, J. (eds.), Spon Press, London.

http://www.gds-staudenfreunde.de/






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Kingsbury, N. J. (2008). An investigation into the performance of species inecologically based ornamental herbaceous vegetation, with particular reference to competition in productive environments. Unpublished doctoralthesis, University of Sheffield.

Kingsbury, N and Oudolf P. (2005) Planting Design: Gardens in Time and Space. Timber

Press, Portland.

Kittur, A., Chi, E., Pendleton, B.A., Suh, B. & Mitkowitz, T. (2006).Power of the Few vs. Wisdom of the Crowd: Wikipedia and the Rise of theBourgeoisie. Available at:http://www.lnl.infn.it/~epics/WikiDumps/localhost/submission_edchi_1.pdf. Viewed 12.March.2010.

Klimes, L., Klimesova, J., Hendriks R., & van Groenendael J. (1997). ‘Clonalplant architecture: a comparative analysis of form and function’, in TheEcology and Evolution of Clonal Plants, (Eds. de Kroon, H. & vanGroenendael, J.), Backhuys, Leiden.

Mackenzie, D.S. (1997). Perennial Ground Covers. Timber Press, Portland.

Pfälzner-Thomsen, G. (1995). ‘Selbstaussamende Stauden’, Garten Praxis,3/1995,.

Rice, G. (ed.) (2006). Encyclopaedia of Perennials. Dorling Kindersley, London.

Rice, G. (2008). ‘Echinacea’, in The Garden, pp. 526-531 (August).

Royal Horticultural Society (RHS) (2007). Proposed revision of the rulesgoverning trials, terms and conditions governing the conduct of RHS trials.

Unpublished internal document. Royal Horticultural Society, London.

Royal Horticultural Society (RHS) (2008). The RHS Award of Garden Merit (leaflet). Royal Horticultural Society, London.

Thoday, P. (2003). ‘Ground Cover’. In Hitchmough, J. & Fieldhouse, K. (eds), Plant User Handbook, A guide to effective specifying, Blackwell, Oxford.

Thomas, G.S (1976) Perennial Garden Plants. Dent,London.

Turner, R. (2009). Tall Perennials, Larger-than-life Plants for Gardens of All Sizes.Timber Press, Portland OR.

Tutin, T.G. et al. (1968) Flora Europaea, Cambridge University Press.

Yeo, P. (1985) Hardy Geraniums, Timber, Portland OR

ACKNOWLEDGEMENTS

Dr. Nigel Dunnett, Mel Burton, Piet Oudolf, Andrew McSeveney, Leigh Hunt, Cassian Schmidt, Jo

http://www.lnl.infn.it/~epics/WikiDumps/localhost/submission_edchi_1.pdf.

http://www.lnl.infn.it/~epics/WikiDumps/localhost/submission_edchi_1.pdf.



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Eliot.; staff of The Garden, The Hardy Plant, Professional Gardeners Guild journal, and with muchgratitude to all participants who filled in questionnaires.

© Noel Kingsbury 2010

PLANT PERFORMANCE QUESTIONNAIRE

PLEASE NOTE - NOT ORIGINAL FORMATTING

Dr. Noel Kingsbury,Associate, Department of Landscape, University of SheffieldMontpelier Cottage, Brilley, HEREFORD, HR3 6HFCONTENTSBACKGROUND 1INSTRUCTIONS 2RESPONDENT DETAILS 3Part 1 GROWING CONDITIONS 3PART 2. PLANT PERFORMANCE 4KEY SPECIES LIST 6PLANT PERFORMANCE RECORD SHEETS

BACKGROUNDThis research is being undertaken as part of the contribution the LandscapeDepartmentat the University of Sheffield are making to an EU project ‘The Interreg IVB NorthSea RegionProgramme – Making Places Profitable’. In a nutshell it means that professionals

and researchersfrom partner organisations (mostly local government and universities) gettogether to shareexperiences about best practice.

Gardeners, public and private, build up extensive knowledge of the plantsthey grow butare not very good at noting it down. This questionnaire is designed to gather information aboutthe long-term performance of herbaceous perennials so that landscape architectsand publicspace managers can create more interesting, beautiful and bio-diverse planting

schemes as aresult of having more confidence in selecting plants which will perform well over time. Thequestionnaire is also designed to test a methodology which can be easilyadapted to gather information about any other category of plants, in any country.

Once the project is finished, the final report will be: _ Distributed to partners in the North Sea Region



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_ Published as an academic paper so that it can be shared amongst thoseteachinglandscape and horticulture – the publication will be open-access, free and online

_ Material will be included in the books and garden magazine articles which aremy output

as a garden journalist _ Included in my teaching materials for garden designers, horticultureprofessionals andamateur gardeners.

INSTRUCTIONSPart 1 GROWING CONDITIONS

This is asking for information about the garden/park where you have hadthe experienceof growing the plant species/cultivars discussed. If your gardening experiencehas involved

growing plants over more than one garden/park, and the geographic location or environment isvery different between them – please contact me, before filling in thequestionnaire.

Part 2 PLANT PERFORMANCE DATAChoose plants from the Key Species List which you have grown for at least 5

years, andwrite their name in the ‘name’ space on the Plant Performance Record SheetsHowever since part of this research is designed to explore plant longevity, short-lived

species (i.e.which live for less than five years) can be included, but only if you have had atleast twoattempts at growing them.1. Please circle the appropriate number for each of the performance factors(detailed in Part2. Plant Performance Data).2. Where you see ‘Please name cultivar you are describing’ on the Key SpeciesList,choose only a relatively well-known one which you regard as typical of thespecies or genus.3. Also please indicate approximately how many years you have grown the plantfor, and if you have any doubt that the plant is not correctly named please tick the ID? box.4. There is also a space for additional comments, e.g. if the species performsdifferently indifferent locations.5. How many plants you provide information for is up to you – I want filling this in



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to beinteresting, even enjoyable. I would appreciate at least 20, but the more themerrier!6. If there are other herbaceous perennials (or short-lived perennials) which arenot on the

list, but which you regard highly – for reliability or visual impact, and which youhave atleast 5 years experience with, please name them and fill out an entry for them.7. How many plants you provide data for is up to you – the more the merrier!Mostrespondents manage 20-30 in an hour – which is the most I can reasonably askfor.8. Thank you!

RESPONDENT DETAILS

NAME OF GARDEN OR PARK………………………………………………………………ADDRESS…………………………………………………………………………….

…………………………………………………………………………………………

NAME OF RESPONDENT…………………………………………………POSITION OF RESPONDENT (i.e. garden owner, gardener, manager)

……………………………………..

Part 1 GROWING CONDITIONS1.0 Soil1.1.1 Summer droughtOften dry in summer _ Occasionally dry in summer _ Rarely dry in summer _ 1.1.2 MoistureGood drainage, excess moisturenever a problem _ Distinctly high moisture content _ Distinctly moist, occasionalwinter waterlogging _ Frequent waterlogging _



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1.1.2 Soil TextureFree-draining, sandy or light _ Loam _ Distinctly clay/heavy _

Poor quality/disturbed _ 1.1.3 FertilityHigh _ Medium _ Low _ 1.1.4 pHAlkaline _ Neutral _ Acid _ 1.2 Local Climate1.1.2 Wind/exposure

Exposed, average, sheltered ? ………1.1.3 AspectNotably north, south, west or east ……….No aspect dominant ……….1.1.4 Other factorsAnything else you regard as importante.g. frost hollow, high altitude ……….

PART 2. PLANT PERFORMANCERefer to and fill in Plant Performance Record Sheets

2.1 LongevityFor each species give a score:1 = very short-lived, rarely more than 3 years2 = short-lived, 3-5 years3 = medium-lived, plants may live 5 years or more, but suddenly disappear 4 = long-lived, plants appear to survive for ever

2.2 Vegetative spreadFor each species give a score:1 = not spreading, staying in same place2 = slowly expanding clump3 = strongly expanding clump4 = spreading through occasional runners5 = spreading strongly through extensive runners6 = discontinuous spread, i.e. spreading outwards but older (1-2 year old) growthdying7 = as above, but vigorously

2.3 Competitiveness



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For each species give a score:1 = very readily overwhelmed by neighbours or weeds2 = readily overwhelmed, but with some ability to survive competition3 = moderately robust, with ability to survive competition4 = moderately spreading, ability to suppress or infiltrate neighbours, or resist

weedencroachment5 = characteristically aggressively spreading, suppressing or heavily infiltratingneighbours

2.4 Speed of establishmentFor each species give a score:1 = slow, acceptable plant size reached in 3 years or longer after planting2 = moderate, acceptable plant size reached in 2 years after planting3 = fast, acceptable plant size reached in first year after planting

2.5 Spread by self-seedingFor each species give a score:(Unless you always dead-head, in which case leave blank).1 = never self-seeds2 = rarely self-seeds, or seedlings rarely reach maturity3 = moderate self-seeding4 = extensive, even nuisance, level of self-seedingSelf-seeding often appears to vary greatly between locations. Where the plant isgrowingin several locations, does self-seeding vary, and what are the differencesbetween the

locations?

Key Species ListAcanthus mollisAchillea millefolium, older cultivars, e.g. ‘Cerise Queen’. Please name cultivar you are describingAchillea – modern hybrids, often named as ‘Galaxy hybrids’, e.g. ‘Hoffnung’,‘Fanal’ etc. Pleasename cultivar you are describingAconitum napellusAlchemilla mollisAmsonia orientalisAnaphalis triplinervisAnemone x hybrida. Please name cultivar you are describingAquilegia vulgarisArtemesia lactiflora Please name cultivar you are describingAruncus dioicusAster x frikartii ‘Mönch’Astrantia major Please name cultivar you are describing



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Baptisia australisBrunnera macrophylla

Campanula latifolia

Centaurea montanaCephalaria giganteaChelone obliquaCrocosmia Please name cultivar you are describing

Dictamnus albus

Echinaea purpurea. Please name cultivar you are describingEchinops. Please name cultivar you are describingEuphorbia cyparissusEuphorbia polychroma

Filipendula rubra 'Venusta'

Geranium 'Johnsons Blue'Geranium phaeum, Please name cultivar you are describingGeranium pratense, Please name cultivar you are describingGeranium renardiiGeranium sylvaticum, Please name cultivar you are describingGeranium x oxonianum, Please name cultivar you are describing

Helianthus 'Lemon Queen'Helleborus x hybridus

Heuchera micranthaHosta. Please name cultivar you are describing

Iris sibirica, Please name cultivar you are describing

Knautia macedonicaKniphofia. Please name cultivar you are describing

Leucanthemella serotinaLiriope muscariLunaria redivivaLysimachia clethroidesLythrum salicaria

Macleaya cordataMiscanthus sinensis, Please name cultivar you are describingMolinia caerulea subsp. arundinacea. Please name cultivar you are describingMonarda, Please name cultivar you are describing



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Nepeta x faassenii

Panicum virgatum, Please name cultivar you are describingPapaver orientale, Please name cultivar you are describingPersicaria amplexicaule, Please name cultivar you are describing

Persicaria bistorta, Please name cultivar you are describingPhlomis russellianaPulmonaria officianalis, Please name cultivar you are describing

Rudbeckia fulgida , Please name cultivar you are describing

Salvia nemorosa/S. sylvatica/S. x superba, Please name cultivar you aredescribingSedum spectabile / S. telephium, Please name cultivar you are describingStipa arundinaceaStipa calamagrostis

Stipa gigantea

Teucrium hircanicumThalictrum aquilegifolium

Vernonia, Please name cultivar you are describingVeronicastrum virginicum, Please name cultivar you are describing.

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long-term performance of ornamental perennials

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