city of toronto guidelines for biodiverse green roofs (2013)

8/18/2019 City of Toronto Guidelines for Biodiverse Green Roofs (2013)

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DESIGN GUIDELINES FOR BIODIVERSE GREEN ROOFS

2 TORONTO CITY PLANNING ZONING BYLAW AND ENVIRONMENTAL PLANNING

Acknowledgements: Prepared by:Scott Torrance Landscape Architect Inc.,with: Brad Bass, Scott MacIvor and Terry McGlade,in conjunction with Toronto City Planning Division

Illustrations:Grace Yang, Scott Torrance Landscape Architect Inc.

Photographs:See individual photographs

Design and Layout:Graphics and Visualization, Urban Design, Toronto City Planning Divison

www.toronto.ca/greenroofs

2013


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TORONTO CITY PLANNING ZONING BYLAW AND ENVIRONMENTAL PLANNING 3

Table of Contents1.0 Introduction and Background 5

2.0 Natural Heritage and Biodiversity Objectives 6

3.0 Opportunities and Constraints 8 3.1 Extensive and Intensive 8 3.2 Roof Types 10 3.3 Native Vs Non Native 10 3.4 Invasive Species 10

4.0 Design Guidelines 11 4.1 Design Factors 11 4.1.1 Depth, Topography and Composition of Growing Media 11 4.1.2 Vegetation Diversity 11

4.1.3 Structures 12 4.2 Design Strategies 13 4.2.1 Increase Depth of Growing Media 13 4.2.2 Vary Composition (Structure) of Growing Media 13 4.2.3 Provide Topographic Variety 13 4.2.4 Provide Microclimates 14

4.2.5 Diversify Plant Species 14 4.2.6 Provide Perching Habitat 14 4.2.7 Provide Nesting Opportunities 15

4.2.8 Provide Water Source(s) 15 4.3 Design Analogues 16 4.3.1 Recreate Native Landscapes 16 4.3.2 Design to Attract Specic Fauna 19 4.3.3 Design to Support Adjacent Ecosystems 22

Sources/Resources 24Appendix A: Recommended Plant Species 25Appendix B: Plant Species to Avoid 33Appendic C: Plants used by Butteries and Caterpillers 35


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About the Green Roof BylawToronto is the rst City in North America to have a bylaw to require and govern the construction of green roofs on new development.

Toronto Municipal Code Chapter 492 Green Roof came into effect on February 1, 2010 and applies to most building permit applications for newdevelopment that are over 2,000m 2 in gross oor area. The Bylaw requires that new development include a green roof covering between 20 and 60percent of the roof area depending on the size of the building.

Toronto Green Roof Construction Standard Supplementary GuidelinesTheToronto Green Roof Construction Standard Supplementary Guidelines provide designers and others with best practices, explanatory material andother green roof resources. TheSupplementary Guidelines contain the following best practices which provide impetus to design to promote biodiversity:• Growth media depth over 100 mm is encouraged.

Vegetation should be:• As de ned in ASTM E2400 - 06 Standard Guide for Selection, Installation, and Maintenance of Plants for Green Roof Systems• Native or adaptive from the Southern Ontario area• Appropriate for the Toronto climate and building exposure• Drought resistant to minimize the need for irrigation• Non-monoculture

1.0 Introduction and BackgroundGreen roofs have many environmental benets. They help reduce theeffects of the urban heat island and associated energy use, managestormwater runoff (reducing the pollutants that enter our waterways),improve air quality and beautify our city. Green roofs also provide anopportunity to create habitat and enhance biodiversity in the urban fabricof the City.

The City of Toronto has a bylaw to require the construction of green roofson most types of new building development. The City also encourages greenroofs through the Eco-Roof incentive program and by providing explanatory

tools and resources through the City’s green roof website. All green roofsin Toronto, including those required by the Green Roof Bylaw, are requiredto meet minimum standards which are dened in the Toronto Green Roof

Construction Standard . Additional guidance for green roof constructionis found in the Toronto Green Roof Construction Standard SupplementaryGuidelines . These Guidelines for Biodiverse Green Roofs identify, describe and illustratebest practices for creating habitat and promoting biodiversity on green roofsin Toronto. They are intended to support and expand theToronto GreenRoof Construction Standard Supplementary Guidelines. These guidelines areprimarily designed for use by architects and landscape architects involved indesigning green roofs but they may also be of interest to others who wish

to understand how green roofs can be designed to enhance and supportbiodiversity.


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Example of hybrid meadow/grassland community. Two views of Robertson Building,215 Spadina, Toronto (McGlade, 2011)

A 2010 discussion paper onUsing Green Roofs to Enhance Biodiversity inthe City of Toronto reviewed literature on green roofs and biodiversity and

identied opportunities, locations and strategies to enhance biodiversity andsupport Toronto’s natural heritage system by increasing the area of habitatfor ora and fauna, acting as transition zones or buffers between naturalhabitats and the surrounding urban area and performing ecosystem services.

Green roof adjacent to High Park, Toronto (McGlade, 2011)

2.0 Natural Heritage and Biodiversity ObjectivesThe City of Toronto Of cial Plan recognizes the importance of protecting,restoring and enhancing the health and integrity of the natural ecosystemand supporting biodiversity. These Guidelines help to implement policies inthe Of cial Plan which seek to support this policy objective.

Toronto Ofcial Plan Policy 3.4.1 “To support strong communities, a competitiveeconomy and a high quality of life, public and private city-buildingactivities and changes to the built environment, including publicworks, will be environmentally friendly, based on:

b) Protecting, restoring and enhancing the health and integrity

of the natural ecosystem, supporting bio-diversity in the City andtargeting ecological improvements”

Green roofs have the potential to enhance biodiversity in urban areas. In theCity of Toronto, green roofs have the potential to contribute a signicantarea of habitat to the urban matrix. A 2005 Report on the EnvironmentalBenets and Costs of Green Roof Technology for the City of Torontoestimated that 21 percent of the total land area in the City is covered withroof and that 8 percent, or approximately 5,000 hectares of City’s landarea, is covered with roof that could be suitable for green roof. The study

concluded that if these areas were converted to green roof they wouldprovide opportunities to recreate some of the habitat and restore some ofthe biodiversity that has been lost due to urbanization.

TORONTO CITY PLANNING ZONING BYLAW AND ENVIRONMENTAL PLANNING6


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When development is proposed in or near the natural heritage system, theOf cial Plan requires that the proposed development’s impact on the naturalheritage system be evaluated and measures to mitigate negative impactsand restore and/or improve the natural heritage system be identied.In keeping with this policy, where a green roof is to be constructed inor abutting the natural heritage system, the Toronto Green Standard encourages applicants to “consider providing a minimum growing mediumdepth of 150 millimetres (6 inches) to accommodate a greater variety ofplant species, to promote biodiversity”.

Toronto’s Natural Heritage SystemToronto’s Natural Heritage Systemis an evolving mosaic of naturalfeatures and functions across theCity, including forest, wetlandand meadow habitats; valley andstream corridors, the shoreline ofLake Ontario and other signi cantnatural features and is connectedto natural systems outside ofthe City including the Greenbelt.Toronto’s natural heritage system isillustrated on Map 9 of the Of cialPlan and is based on a NaturalHeritage Study (2001) whichidentied and mapped the locationof natural features and functionsacross the City.



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Extensive Green Roof, 75mm depth, sedums and chives only; Victoria Park SubwayStation, Toronto (Torrance, 2009)

Example of hybrid meadow/grassland community, extensive green roof, 150 mmdepth at Jackman Public School, Toronto (McGlade, 2011)

Toronto Green Standard is a two-tier set of performance measuresfor sustainable site and building design for new private and publicdevelopment. TheToronto Green Standard requires green roofs onbuildings included in the City of Toronto Green Roof Bylaw andencourages green roofs on other buildings.

3.0 Opportunities and Constraints

3.1 Extensive and Intensive

Green roofs can be classied as either extensive or intensive, depending onthe depth of substrate used and the level of maintenance required. Mostof the green roofs that have been constructed under the Toronto’s GreenRoof Bylaw are extensive green roofs. Extensive green roofs generallyhave shallow, well drained substrates and hot dry conditions that aregenerally only suitable for a few drought tolerant species and minimalbiodiversity. Intensive green roofs have deeper substrates that can supporta greater variety of habitats and biodiversity. Green roofs can also involve acombination of the two types.


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Key differences between extensive and intensive green roofs

Roong Element Extensive Green Roof Intensive Green Roof

Growing Media/ StructuralPreparation

• Depth of growing media generally between50 - 100 mm (2 – 4 inches)

• Minimal to no irrigation• Light weight• Structural engineering usually not required• Suitable to cover large surface areas

• Depth of growing media greater than 100 mm(4 inches)

• More likely to require irrigation• Heavier in weight• Requires structural engineering• Used over smaller areas or in landscaped containers

Vegetation• Stressful conditions for plants requires low

growing drought resistant species• Can support few plant species, generally monoculture

• Deeper substrate can support wider range ofnative plant species

• Can be designed to simulate greater range ofplant species and habitats

BiodiversityCharacteristics

• Shallow substrates subject to the effectsof freezing and extreme drought. Overwinteringsurvival is low.

• Limited opportunity to incorporate habitat features• Little opportunity for habitat functions

• Deeper substrate depths buffer against the effectsof freezing and extreme drought

• opportunities to incorporate habitat features formobile species such as birds and insects

• Greater opportunity for restoration of habitatfunctions

Source: Using Green Roofs to Enhance Biodiversity in the City of Toronto, 2010.



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3.3 Native Vs Non Native

There is ongoing debate about the use of native versus non-native or exoticplants. There are several arguments in favour of using native plants. Nativeplants are well adapted to local environmental conditions and are more

likely to form self-sustaining plant communities that require less long-term maintenance, because they are already adapted to this climate and itsextremes. Native plants also provide important sources of food and shelterfor native birds, butteries and other insects. Use of local vegetation inplanting design may also allow colonization by other local species to occurmore quickly as they are already adapted to the native vegetation.

There are also several arguments in favour of using non-native plantsprimarily because the climate on a roof is different than on the ground. Itis generally hotter and drier, and many native plants do not adapt well tothis environment. There are non-native plants that are already well-adaptedto growing in conned spaces, and these plants may be better suited togrowing on a roof. For example Sedum varieties from alpine regions have aproven track record on green roofs and these plants can still be used as partof a green roof that is designed to provide habitat for birds and insects.

3.4 Invasive Species

Certain invasive plants can colonize green roofs. These are mostly‘hitchhikers’ in soil or plant material intentionally planted during installationbut also some plants species with very mobile seeds dispersed by wind orby birds. A species which is not typically invasive may act invasive undercertain conditions (e.g., Canada goldenrod and Manitoba maple). Plantcolonizers require free nutrients to get established, and a high diversity ofplants can be used as a strategy to minimize free nutrients, thus reducingor eliminating the ability of invasive species to colonize a green roof.Some colonizers like dandelion (Taraxacum ofcinale ) provide considerablenectar and pollen resources for many kinds of bene cial insects, as doesbird vetch (Vicia cracca ) a nitrogen- xing leguminous plants that improvesaccessibility of other plant species to this essential soil element.

3.2 Roof Types

No roof necessarily presents the optimal environment for creatinga biodiverse ecosystem, but where there are constraints, there areopportunities. A rooftop is already a harsher environment than what

most plants encounter on the ground - a result of higher temperatures,higher wind speeds and reduced water-holding capacity in comparison tomost environments existing at ground-level. In full sun, these stresses areexacerbated, necessitating the need for regular irrigation. Flat roofs that can support an intensive green roof may only be constrainedby cost, sun or shade. Many at roofs will become extensive green roofsdue to limitations on the roofs weight-bearing load and/or budgetaryconsiderations. Flat roofs do not have signicant variability in waterdrainage and offer lower niche diversity, and thus less opportunity fordifferent plants to exploit these novel habitats. Opportunities may exist tovary growing media topography by adding depth on those parts of the roofthat can support the additional load (e.g. above structural areas). Sloped green roofs are not as common in North America as they are inEurope because more structure is required to keep the growing mediain place, which in turn raises cost. However, sloped roofs may allow for(or require) a wider plant palette in comparison to a topographicallyhomogenous extensive green roof. The upper regions of a sloped roof willdrain faster than lower regions, creating niches for different plant speciesbetter adapted to drier conditions (e.g. Sedums ) at the high side andwetter conditions (e.g. grasses, asters) in the low areas. Gravity, wind, anddry conditions can topple loose soil and plant material, particularly sincesloped roofs often do not have a parapet for added protection. In termsof moisture, adding slope is analogous to adding depth on an increasinggradient from top to bottom. Sloped roofs may also provide areas of partialto full shade if they use shed or hip congurations. This necessitates plantspecies selection to withstand these varying light conditions.


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In Toronto, the diversity of plants that can survive increases dramaticallywhen depth of growing media increases from 100mm to 150mm (4 – 6inches). Green roof substrate depths above 100mm (4 inches) or morewill help to avoid signi cant die-back in the winter or during hot summer

months. Topographic variation in substrate depth across a green roof is also a wayto increase biodiversity by creating a series of different microclimates, andsubsequently microhabitats, within the same green roof zone. Thin substrateareas allow sparse vegetation to develop, whereas small hills or mounds ofthick substrate support taller, denser vegetation. Depth can only be addedon those parts of the roof that can support the additional load. Composition of the growing media can play a role in supporting biodiversity

by varying the granule size of the substrate. Recreating native soil structure,or aggregate composition may also be considered, although little researchhas been completed on this subject. Gravel can also be used on bare areason a roof to create habitat diversity however the Green Roof Bylaw restrictsthe use of substrate based extensive green roofs due to the requirement of80 percent coverage and noxious weed restriction (if self-seeding is to berelied upon). One strategy would be to meet the minimum area requiredby the Green Roof Bylaw and achieve 80 percent coverage, while providingother non-planted areas to allow self-seeding. Removal of noxious weedsfrom these areas would need to be part of the ongoing maintenance plan.

4.1.2 Vegetation DiversityThe vegetation layer of a green roof plays a signicant role in fosteringbiodiversity. Maximizing the diversity of plant species and plant life forms(succulents, herbaceous perennials, woody plants, coniferous, deciduous,etc.) has many benets, increasing the opportunities for pollination andfood, shade, nesting, perching, nutrients, etc. Large roofs or roofs with highload bearing capacity provide the greatest opportunity for diversity by

Aggressive invasive species such as garlic mustard and buckthorn, whichare a threat to urban ecosystems. typically, these plants do not becomeestablished on green roofs due to the elevation, substrate depth andnutrient prole of green roofs.

A list of recommended plant species (native and non-native) is provided inAppendix A. Plants to avoid are found in Appendix B.

4.0 Design Guidelines

4.1 Design Factors

There are three design factors that have been linked to the creation of

biodiverse green roofs: • Variation in depth, topography and composition of growing media,• Vegetation diversity, and• Structures to create niche spaces for organisms

These three factors are described and illustrated below.

4.1.1 Depth, Topography and Composition of Growing Media

Depth of growing media or substrate is a considerable constraint on thevariety of habitats that can be created on a green roof. Roof environmentsare subjected to many stresses such as intense temperature and moisturechanges, so shallow substrates can intensify the already extreme ecologicalconditions. In general, as the depth of growing media increases, theopportunity to promote biodiversity also increases, simply because a greaterrange of plant species and plant types can be accommodated. Installationcosts (both for the vegetated assembly and the structure to support it)increase as depth of growing media increases. Maintenance and irrigationrequirements may increase as well for deeper roofs.


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Recirculating bubbler fountain with no open water on green roof at 30 College Street,

Toronto (Torrance, 2011)

permitting a greater range of vegetation type and size, including trees andshrubs, but extensive green roofs provide excellent opportunities to creategrassland communities. The most common extensive green roofs are planted with sedums.Establishment of monoculture green roofs will generally necessitate greatermaintenance and careful monitoring to ensure proper viability of the singlespecies. 4.1.3 Structures

The use of structures is a simple approach that can be used to manipulateand increase the utilization of the roof as habitat. One technique thatcan be integrated almost anywhere on the roof is the addition of mediumto large natural objects, such as branches or stones (these may need tobe fastened down), or even rubble, all of which help to create differentmicroclimates and microhabitats which may lead to greater speciesdiversity. Similarly, branches can provide physical connections and shadyhabitats and serve as resting sites for birds to perch and as nestingstructures. Bird or bat boxes can also be added to encourage species to nestand breed.



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nesting and to collect mud for nesting material. Earthworms would need aloose, coarse, more organic growing media than typical green roof mineralmixes provide to survive. High organic growing media can be combined withlow organic, mineral-based growing media across the roof. Gravel can alsobe used on bare areas on the roof.

vary granule size

vary mixtures

incorporate bare areas of gravel

4.2.3 Provide Topographic Variety

Topographic diversity increases soil depth and microclimatic variation.Sloped surfaces are typically drier at the top and wetter at the bottom. Thisvariation creates an opportunity for different plant selection to correspondto this micro-hydrological regime. Topographic diversity can also beimplemented using different heights of edging, modules and planters.

4.2 Design Strategies

4.2.1 Increase Depth of Growing Media

In Toronto, The diversity of plants that can survive increases dramaticallywhen the depth of substrate (growing media) is increased from 100 mmto 150 mm (4 to 6 inches). One option is to increase the depth across theentire roof, an alternative is to increase the depth of substrate on the partsof the roof that can support the additional load (e.g., above structural areas)and provide greater planting diversity on these areas.

A list of plant species and minimum growing depth is provided in Appendix A.

4.2.2 Vary Composition (Structure) of Growing Media

Structure can play a role in supporting biodiversity by varying the granulesize of the aggregates in the substrate and the spread of different mixturesupon the roof area. Soils often have a particular distribution of granules,and native soils can be analyzed in order to reproduce the range ofgranularity. Varying the composition of growing media creates opportunitiesfor greater diversity of plant species and habitats, most notably insects andsoil nematodes. For instance, some species of spiders, solitary bees and pestcontrolling wasps need bare, non-compacted, small particulate soil areas for


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4.2.5 Diversify Plant Species

Maximizing the diversity of plant species and plant life forms (succulents,herbaceous perennials, woody plants, coniferous, deciduous, etc.) has manybenets, increasing the opportunities for pollination and food, shade, nesting,

perching, nutrients, etc. Depending on maintenance levels, which are typicallyminimal on green roofs, succession of plants overtime must be considered as anatural consequence (or benet) of a diverse planting strategy.

4.2.6 Provide Perching Habitat

Objects, such as rocks, logs, branches or constructed elements can beintegrated into green roofs to attract birds and insects to perch. Someobjects, such as logs and branches, may need to be secured to the roof.Metal should be avoided due to heat absorption.

rocks

forbs, grasses and shrubs

branches and platforms

logs

4.2.4 Provide Microclimates

Objects, including building elements, provide microclimatic opportunities inthe typically uniform full sun and dry condition found on green roofs. Areasin shade and below objects will be cooler and moister, providing habitat

diversity opportunities, especially for insects and soil organisms.

rocks

plants

lots

buildings elements



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4.2.8 Provide Water Source(s)

Water is one of the principle limiting resources for most species that wouldotherwise be able to use green roofs as permanent habitat. These effects

are exacerbated given that green roofs are hotter and more exposed thanmost ground-level habitat. Puddles or vernal pools will not form or last long.For example, many bird species may nd green roofs to be suitable nestingspace, but once chicks hatch, periods of drought can be fatal. A source ofwater can be provided in two ways: either pumped or collected. Pumpedand recirculated water features require energy and regular maintenance(cleaning, topping up with fresh water, seasonal closing, etc.). Rainfall canbe collected in depressions and basins. Maintaining water on a roof, eithernatural from precipitation or articially (with a pump or fresh water supply)may not be desirable from a building science perspective and can create

habitat for mosquitoes.

basins

bird baths

water features

naturally pitted cap rock

4.2.7 Provide Nesting Opportunities

Elements to encourage nesting opportunities for birds and insects can beintegrated into green roofs. Some insects and birds (e.g. killdeer) use bareareas of soils and gravel for nesting. Bird and bee houses require regularcleaning and maintenance if they are utilized. Some objects may need to besecured to the roof.

Tall grasses and shrubs

Birdhouses

Logs and branches

Open soil areas

Bee nest boxes


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4.3 Design Analogues

4.3.1 Recreate Native Landscapes

Green roofs can be designed to mimic almost any habitat and also provide

an opportunity to recreate specic native landscapes. Habitats such asgrasslands and herb communities are well suited to intensive roofs.

Green roofs have been found to be broadly analogous to certain types oflandscapes, from which plants are seemingly pre-adapted to the harsh greenroof environment. Selecting plants from habitats that exhibit microclimaticcharacteristics similar to green roofs increase chances of discoveringsuitable plants. These include permanently open habitats such as rockyoutcrops, cliffs, dunes, heathlands, and alvars.

Green roof designed with many different depths of growing medium, as well asopen soil areas, in order to support a diversity of trees, shrubs, grasses, forbs andsucculents. ESRI Canada, Toronto (Torrance/Mulligan, 2010)

Green roof with 75mm to 500mm growing depths, deep enough to support a varietyof native prairie plants. Design includes structures for perching and nesting andwater feature to attract wildlife. Native Child & Family Services, Toronto (Torrance,2009)


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palette. An overarching philosophy of maximizing species diversity and thenallowing plants to colonize themselves will help build resiliency throughadaptability into the green roof ecosystem. A list of plants and minimumsoil depths is provided in Appendix A.

Tallgrass Prairie, Walpole Island First nation, Essex County, Ontario

(J.L. Riley from Ecological Land Classi cation for Southern Ontario, 1998)

Four of these habitat types are potential analogues for green roof plantselection and growing media composition: tallgrass prairie, alvars, fens andsand barrens.

Tallgrass Prairie

Dening Characteristics:• Grassland with variable cover of small woody shrubs and

open-grown trees• Subject to seasonal extremes in moisture conditions• Tolerates spring ooding and summer drought• Regenerated by re disturbance

Growing Media Composition:• Unconsolidated mineral substrates with a soil depth of > 150mm• Typically consists of well-drained sands, loams, and sometimes clay

Plant Selection:• Dominated by prairie grasses, forbs, sedges, small woody shrubs and

open-grown trees

Other Considerations:It is not wholly accurate to use the tallgrass prairie habitat as a template forgreen roof design, as species diversity is lower and conditions on extensivegreen roofs vary considerably from those found in a natural tallgrass prairiehabitat. Soil depth is less then found in the natural habitat, conditions tendto be drier and windier and soil quality is poorer. For these reasons, grassescannot establish their roots as extensively. Fire disturbance – a naturalphenomenon that supports vegetative regeneration – is also absent ongreen roofs.

An alternative is to create a hybrid meadow/grassland plant community.If only a 100mm soil depth can be achieved, a much more limited numberof plant species can be used. A minimum soil depth of 150 mm will supporta greater diversity of species and thus a more comprehensive planting


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Fens

Dening Characteristics:• open habitats• wet almost all year• soils are high in organic content (a result of decomposing plant

material), contain peat, and are often saturated• support a wide diversity of plant and insect species

Growing Media Composition:• organic-rich soils, as deep as possible, with some aggregates

Plant Selection:• dominated by sedges, grasses, forbs, mosses, and some woody plants

Other Considerations:

Buildings that produce high volumes of wastewater (e.g. air conditioners,industrial processes), are lower to the ground and less exposed, are goodcandidates for incorporating fen habitat analogs into their green roofdesign. It is not economically or environmentally feasible to use fen habitatas templates for green roof design if only potable water is available forirrigation. The best strategy is to route wastewater onto the roof, keeping itsaturated as often as possible during the spring, summer, and fall seasons.

Fen, Emily River Fen, Victoria County, Ontario(J.L. Riley from EcologicalLand Classi cation forSouthern Ontario, 1998)

Alvars

Dening Characteristics:• naturally open landscapes with little or no tree cover• patchy distributions of loamy and sandy soils at heterogeneous depths• soil texture is generally a loam

Growing Media Composition:• shallow depths (less than 20cm)• depressions interspersed among bare rocky patches• generally wet in the spring and severely dry in the mid-summer• contain distinctive species which are adapted to harsh green roof

environments, as well there are many rare species

Plant Selection:• patchy distribution of grasses and forbs

Other ConsiderationsAlvars have patchy distributions of loamy and sandy soils at heterogeneousdepths, a result of natural depressions in the underlying limestone bed,and surrounding exposed rock. Soil texture is generally a loam. Green roofsusing alvar habitat analogs as a design focus will want growing media withorganic matter, shallow depths (less than 20cm) and depressionsinterspersed among bare rocky patches. These habitat analogs will need tobe generally wet in the spring and severely dry in the mid-summer.

Alvar, Bruce Alvar NatureReserve, Bruce County, Ontario(J.L. Riley from Ecological LandClassi cation for Southern

Ontario, 1998)


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TORONTO CITY PLANNING ZONING BYLAW AND ENVIRONMENTAL PLANNING

4.3.2 Design to attract specic fauna

Green roofs can be designed to attract and support certain fauna, typicallybirds and insects, whether they are native, rare or require stopping points on

a migration route. This can be done by designing the roof to provide certainfeatures that these fauna require on the landscape, but not necessarily thecomplete habitat.

Birds

Urban development and loss of habitat have impacted travel distances,expended energies, and reduced the availability of food sources formigratory birds passing through. Green roofs provide vegetation wherethere would otherwise be none and create temporary foraging habitat for

local and migratory birds. Grasses and herbaceous plants that producenumerous seed heads can provide invaluable energy sources for migratorybirds. Perches and nesting boxes can provide opportunities for resting andbreeding.

Sand Barrens

Dening Characteristics:• restricted tree growth• full exposure to sun• poor soil quality

Growing Media Composition:• sandy and well-draining• heterogeneous depths and a mix of larger aggregates

Plant Selection:• slow-growing shrubby grassland and heathland mosaics, dotted with a

high diversity of herbaceous plants• drought tolerant

Other Considerations:It is recommended to not design an entire roof after the Sand Barrencommunity, as sandy soils are more likely to erode from the rooftop bywind. Instead, patches of sand barren habitat can be considered. Whenpatches are planted, use soil stabilizers and erosion control netting untilthe plants establish to minimize soil loss.

Sand Barren, Giant’s TombIsland Nature Reserve,Simcoe County, Ontario(J.L. Riley from EcologicalLand Classi cation forSouthern Ontario, 1998)

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Green roof elements designed to attract birds, providing nesting and perching opporunities,at University Hospital, Basel, Switzerland (Bass, 2003)

Migratory Birds in the City of Toronto

A 2009 report Migratory Birds in the City of Toronto identies the

potential of green roofs as temporary stopover habitat for migratoryspecies especially when ying over extensive urbanized areas en routeto more suitable habitat. Green roofs might also pose a hazard tobirds passing over the city by increasing its chance of colliding withreective glass adjacent to the roof. The City’sBird-Friendly Development Guidelines can be implemented on portions of buildings adjacent togreen roofs to help reduce bird fatalities.

Migratory Birds in the City of Toronto

Bird-Friendly Development Guidelines


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provide permanent nesting space for these species on rooftops.

Bee nesting box, 410 Richmond Street, Toronto (MacIvor, 2011)

Other Insects

Green roofs may provide habitat for pollinating insects such as bees,

ies, and butteries, but also other functionally important invertebrates.These include those critical for nutrient cycling and decomposition,such as springtails, millipedes, beetles, and worms; predation of pestspecies by spiders, solitary wasps, dragonies and damselies; and manyas food for other desirable species in cities, like birds. Although manyurban invertebrates may only use a green roof habitat temporarily, somespecies, particularly those soil-dwellers important for nutrient cyclingand decomposition can be permanent inhabitants, and so require someconsideration in green roof planning to ensure populations can colonize andpersist. Greater growing media depths, plant canopy, and features like logs,

Bees

There are many species of pollinators, including bees, ies, moths, andbutteries that can incorporate green roofs into their foraging ranges. Bees,in particular, being highly mobile, mostly polylectic (meaning, they can visitmany different kinds of owers), and adapted to spatially separate nestingand foraging resources, are very well suited to receive support from greenroofs designed with foraging and nesting resources in mind. This is all themore important as bee populations decline worldwide. Bees need owersfor pollen and nectar, and green roofs with diverse plant palettes to prolongblooming are most valuable. In cities, wild bee diversity seems to positivelyrespond to increases in total plant diversity. Roofs planted entirely withSedum, or similar species, also provided pollen and nectar for many bees,but only ower for only a short period so act only as temporary resources.

If one of the objectives is to keep honeybees on the green roof, water shouldbe available at all times in buckets or pans, an open rain barrel, or preferablya continuous fresh water source. Honeybees need to collect large amountsof water to maintain healthy hives. The water is used to dilute honey to feedto larva, and to cool the hive through evaporation in hot weather.

Interestingly, many pollinators are highly-mobile and adapted to spatiallyseparated foraging and nesting areas. As such, many bees can reach greenroofs and once there may nd permanent (nesting and forage) or temporary(forage only) refuge; thereby incorporating green roofs into their foragingranges. Since approximately 60 percent of Toronto’s bee species nest in theground, green roofs designed to support bees might include areas of baresoil, soil topographic heterogeneity, and a plant community with an extended

owering period. Many other bees nest in stems and pre-existing cavities,so maintenance that includes not cutting plant stems down to the soil(leave 150 mm (6 inches) or more, if possible), adding dead wood as a designelement, or even nestboxes, comprised of holes drilled into wood, or bundledreeds or paper tubes plugged at one end added as a roof feature could


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large stones or pavers are all important to reduce exposure and keep someareas slightly more damp and cool. This is essential for survival of soil-dwelling and low-mobility species during the driest and hottest times of theyear.

Many highly-mobile, species like bees, butter ies, dragon ies, and birdscan incorporate one or more green roofs, both intensive and extensive, intotheir foraging range. These species may source requirements for survival andreproduction from a green roof, such as food (pollen, nectar, prey), or shelter(nesting material, locations, oviposition and metamorphosis sites).

Species that nd permanent refuge on an extensive green roof may havelow resource requirements for survival and successful reproduction. Forexample, some small ground-nesting eusocial and solitary Lasioglossum

bees can provision larvae with pollen and nectar in very shallow, well-draining sunny soils. These bees are very effective pollinators, but dueto their small size can meet all of their foraging requirements fromsmall patches of owering plants of different species. Other desirable,permanently inhabiting green roof species include spiders, predatory beetles,and solitary wasps each of which effectively collect and feed on pest insectsthat inict damage and harm green roof plants.

A list of plants used by butteries and caterpillers is provided in Appendix C.

4.3.3 Design to support adjacent ecosystemsGreen roofs located near or adjacent to natural heritage areas can bedesigned to expand and support these neighbouring ecosystems. Greenroofs can act as transition zones or buffers between natural habitatsand the surrounding urban area and perform ecosystem services such asproviding food for pollinators and resting, feeding and breeding space forlocal and migratory birds. Green roofs located near or adjacent to naturalheritage areas should look to how their design can enhance and improvethe condition of the natural habitats. For example, new development

close to a ravine could specify plants that will create an edge condition tothe ravine and use existing plant communities to inform the selection ofappropriate species on the roof to effectively expand the planted area ontothe tableland.

The table on the following page outlines design objectives and strategies forgreen roofs in specic locations in the City of Toronto.

Design Objectives and Strategies for Green Roofs in SpecicLocations in Toronto

Extensive Green Roof Adjacent to Rosedale Ravine, Toronto (Torrance, 2008)


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Green Roof Location Objectives Design Strategies Species for Conservationor Protection

Areas adjacent to foresthabitat (e.g., river valleys,High Park, Rouge Park).

Enhance/buffer adjacentecozones and link green roofsto forest ecosystems at gradelevel. Benecial matrix inuencethrough climate and hydrologicalmitigation to buffer adjacentforest ecosystems.

Provide perching/ breeding/feeding opportunities formigratory birds, butteries andinsects.

Provide habitat for native plants.

Create higher order “climax”ecosystems; use small shrub andtree species.

Enhance property perimeterregions at grade level to scale upavailable shrubs and other forestconstituents.

Design for aggregations of greenroofs on clusters of buildings.

Forest Interior birds, rare plants,native shrubs/small trees,pollinators including butteries(along with other trophicbenefactors eg. microbial soilconstituents).

Areas adjacent to LakeOntario shoreline, rivervalley corridors.

Extend perching/ breeding/feeding zones for migratory birds,butteries and insects.

Provide habitat for nativemeadow/prairie plants

Meadow grasses (native andnon-native) perennials + tallgrass prairie species; also trypre-vegetated mat systems withaugmentations in substratedepths/shapes/ mounds wherepractical. Include plants thatproduce abundant seeds to feed

early spring migrants.

Migratory birds and butteries,native plants, insects and otherpollinators (along with othertrophic benefactors).

Alvar species.

Areas adjacent to meadowhabitat (e.g., along hydrocorridors).

Extend meadow/grasslandhabitats and support zones formigratory birds, butteries andinsects.

Provide habitat for nativemeadow/prairie plants.

Meadow, grasslands orpre-vegetated mats withaugmentations to substratedepth as practical.

Meadow plants, grass andshrubland birds, butteries andinvertebrates.

Alvar species and possibly somemeadow marsh species wherewater is retained more.

Source: Using Green Roofs to Enhance Biodiversity in the City of Toronto, 2010.

Design Objectives and Strategies for Green Roofs in Specic Locations in Toronto


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Sources / Resources

Bird-Friendly Development Guidelines. 2007. City of Toronto.http://www.toronto.ca/planning/environment/guidelines.htm

City of Toronto Natural Her itage Study. 2001. City of Toronto and Toronto and Region Conservation Authority.http://www.toronto.ca/planning/environment/pdf/natural_heritage/natural_text1.pdf

Ecological Land Classication for Southern Ontario. 1998. First Approximation and Its Application. H. T. Lee, W.D. Badowsky, J.L. Riley, J. Bowles,M. Puddister, P. Uhig, S. McMurry. 1998. Ontario Ministry of Natural Resources. Southcentral Science Section, Science Development and TransferBranch. SCSS Field Guide FG-02.

Migratory Birds in the City of Toronto. 2009. Prepared for Toronto City Planning. Prepared by North-South Environmenta l Inc. and Dougan &Associates. http://www.toronto.ca/planning/environment/pdf/migratory_birds_15aug09_small.pdf

Toronto Green Roofshttp://www.toronto.ca/greenroofs/index.htm

Toronto Green Roof Construction Standard (Article IV of Toronto Municipal Code Chapter 492 Green Roof)http://www.toronto.ca/legdocs/municode/1184_492.pdf

Toronto Green Roof Construction Standard Supplementary Guidelines.http://www.toronto.ca/greenroofs/pdf/GreenRoof-supGuidelines.pdf

Toronto Green Standardhttp://www.toronto.ca/planning/environment/index.htm

Toronto Municipal Code Chapter 492 Green Roof http://www.toronto.ca/legdocs/municode/1184_492.pdf

Toronto Ofcial Plan. 2010http://www.toronto.ca/planning/of cial_plan/pdf_chapter1-5/chapters1_5_dec2010.pdf

Report on the Environmental Benets and Costs of Green Roof Technology for the City of Toronto. 2005. Prepared For City of Toronto andOntario Centres of Excellence – Earth and Environmental Technologies (OCE-ETech). Prepared By Ryerson University Professors Dr. Doug Banting,Professor Hitesh Doshi, Dr. James Li, Dr. Paul Missios and Students Angela Au, Beth Anne Currie, Michael Verrati. http://www.toronto.ca/greenroofs/pdf/fullreport103105.pdf

Using Green Roofs to Enhance Biodiversity in the City of Toronto. 2010. A Discussion Paper Prepared for Toronto City Planning. Beth AnneCurrie and Brad Bass. http://www.toronto.ca/greenroofs/pdf/greenroofs_biodiversity.pdf


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Appendix A: Recommended Plant Species

Plant species should be selected rst for their ability to survive the conditions they will grow in, considering:• depth of growing media

• slope of roof, if any• amount of sunlight available• type of irrigation that will be provided (manual, automatic, none)• wind exposure• maintenance levels• location (i.e. adjacent to natural heritage area or not)• program (desired look, approach, program desired)• hardiness zone (depending on roof level, at least one zone hardier than Toronto’s hardiness zone of 6)• availability in the nursery trade• conformance with Green Roof Bylaw• Succession of plants over time

Once plant species are determined based on the above criteria, the type of growing media should be selected:• low organic matter content i.e. FLL, 10% by weight• The use of native and adaptive species should be maximized.

Based upon data collected in 2004 and 2005, the Toronto and Region Conservation Authority developed a list of native plants for a green roofenvironment in Toronto: http://www.toronto.ca/greenroofs/pdf/plant_suggestions2007.pdf. The following plants are recommended for use in Toronto green roofs:

Native GrassesBotanical Name Common Name Min. DepthBouteloua curtipendula Side-oats Grama 150mmBouteloua gracilis Blue grama grass 100-150mmCarex Pennsylvannia,Nigra Sedge 150mmChasmanthium latifolium Northern Sea Oats 100-150mmDeschampsia cespitosa Tufted Hair Grass 100-150mmPanicum virgatum Switch Grass 100-150mmSchizachyrium scorparium Little Bluestem 100-150mm


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Native ForbsBotanical Name Common Name Min. DepthAsclepias tuberose Butter y Milkweed 150mmAster laevis Smooth Aster 150mmCampanula rotundifolia Harebell 150mmEchinacea pallida Pale Purple Coneower 150mm

Epilobium angustifolium Fire-weed 150mmEupatorium purpureum Joe-Pye Weed 150mmEupatorium perfoliatum Boneset 150mmGentiana andrewsii Bottle Gentian 150mmGeum triorum Prairie Smoke 150mmHedyotis longifolia Long-leaved Bluets 150mmLiatris cylindracea Cylindric Blazing Star 150mmLiatris spicata Dense Blazing-star 150mmLobelia siphilitica Great Blue Lobelia 150mmLobelia cardinalis Cardinal ower 150mm

Lupinus perennis Wild Lupine 150mmLysimachia quadriora Prairie Loosestrife 150mmMaianthemum stellatum Starry False Solomon’s Seal 150mmMonarda didyma Beebalm (Oswego Tea) 150mmMonarda stulosa Wild Bergamot 150mmPenstemon digitalis Foxglove Beardtongue 150mmPolygonatum pubescens Downy Solomon’s Seal 150mmPhysostegia virginiana Obedient Plant 150mmRudbeckia hirta Black-eyed Susan 150mmRatibida pinnata Gray Headed Coneower 150mmSolidago ptarmicoides Upland White Goldenrod 150mmSolidago squarrosa Stout Goldenrod 150mm

Verbena simplex Slender Vervain 150mm Verbena stricta Hoary Vervain 150mm Veronicastrum virgin icum Culver’s Root 150mm

Native EvergreensBotanical Name Common Name Min. DepthJuniperus communis var. depressa Common Juniper 300mmJuniperus horizontalis Creeping Juniper 300mmThuja occidentalis White Cedar 300mm


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Native Woody PlantsBotanical Name Common Name Min. DepthAmelanchier laevis Saskatoon Berry 200mmAmelanchier stolonifera Smooth Serviceberry 200mmAronia melanocarpa Chokeberry 200mmCephalanthus occidentalis Buttonbush 200mm

Celastrus scandens Bittersweet 200mmCladrastis lutea Yellowwood 200mmCornus alternifolia Pagoda Dogwood 200mmCornus amomum Silky Dogwood 200mmCornus canadensis Bunchberry 150mmCornus racemosa Grey Dogwood 200mmCornus sericea Red Osier Dogwood 200mmDiervilla lonicera Bush Honeysuckle 200mmHamamelis virginiana Witch Hazel 200mmHypericum kalm. Kalm’s St. John’s Wort 200mm

Ilex verticillata Winter Berry 200mmMyrica pennylvanica Bayberry 200mmParthenocisus virginiana Virginia Creeper 200mmPhysocarpus opulifolius Ninebark 200mmRhus aromatica Fragrant Sumac 200mmRhus glabra Smooth Sumac 200mmSalix exigua Sandbar Willow 200mmSambucus canadensis Green Elder 200mmSambucus pubens Scarlet Elder 200mmSpirea alba Narrow Leaf Meadowsweet 200mmSpirea tomentosa Steeplebush 200mmSymphoricarpus albus Snowberry 200mm

Viburnum dentantum Arrowwood 200mm Viburnum lentago Sheepberry 200mm Viburnum trilobum Highbush Cranberry 200mm Vitis riparia Riverbank Grap 200mm


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Non-Native GrassesBotanical Name Common Name Min. DepthCalamagrostis X acuti ora ‘Karl Foerster’ Karl Foerster Feather Reed Grass 150mmCalamagrostis X acuti ora ‘Overdam’ Overdam Feather Reed Grass 150mm

Non-Native ForbsBotanical Name Common Name Min. DepthAstilbe chinensis Chinese Astilbe 150mmAllium shoenoprasum Chives 100-150mmBergenia cordifolia Bergenia 150mmCentaurea montana Bachelor’s Button 100-150mmCerastium tomentosum Snow-in-Summer 100-150mmDianthus deltoides Maiden Pinks 100-150mmEchinacea purpurea Eastern Purple Cone ower 150mm

Echinops ritro Blue Globe Thistle 150mmGeranium sanguineum Bloody Cranesbill 100-150mmHemerocallis sp. Daylily 100-150mmHosta sieboldiana Siebold Hosta 150mmIris setosa Dwarf Arctic Iris 100-150mmLavandula angustifolia English Lavender 100-150mmPhlox paniculata Summer Phlox 100-150mmPhlox subulata Moss Phlox 100-150mmRudbeckia nitida Coneower 150mmThymus citriodorus Lemon Thyme 100-150mm

Thymus serphyllum Creeping Thyme 100-150mm Veronica incana Silver Speedwell 150mm

Non-Native Woody PlantsBotanical Name Common Name Min. DepthCornus alba Sibirica Pearls 200mmCornus sericea ‘isanti’ Isanti Red-Osier Dogwood 200mmHydrangea arborescens Annabelle 200mmPotentilla fruticosa Bush Cinquefoil 200mmPotentilla tridentata ‘Nuuk’ Wineleaf Cinquefoil 200mm


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Prunus X cistena Purple Leaf Sand Cherry 200mmRhodendron ‘Aglo’ Aglo Rhododendron 200mmSpirea bumalda ‘Goldmound’ Spirea Goldmound 200mmSyringa vulgaris Common Liliac 200mmWeigela orida ‘French Lace’ French Lace Weigela 200mm

Forbs – Full SunBotanical Name Common Name Min. DepthAchillea sp Yarrow 100-150mmAnaphalis margaritacea Pearly everlasting 150mmAquilegia Canadensis Columbine 100-150mmAsclepias tuberosa Butter y Milkweed 150mmAster laevis Smooth Blue Aster 150mmAster nova-angeliae New England Aster 150mmCampanula rotundifolia Harebell, Bluebell 150mmEchinacea angustifolia Narrow Leafed Coneower 150mmEchinacea pallida Pale Purple Coneower 150mmEupatoriummac purpureum Joe Pye Weed 150mmEquisetum hymenale Horsetail Grass 100-150mmFragaria virginia Virginia Strawberry 100-150mmHelianthus salicifolius Willow-leaved Sun ower 150mmHelenium autumnale Common sneezeweed 150mmLiatris cylindracea Cylindric Blazing Star 150mmLiatris spicata Dense Blazing-star 150mm

Lobelia siphilitica Great Blue Lobelia 150mmLobelia Cardinalis Cardinal ower 150mmMonarda didyma Beebalm (Oswego Tea) 150mmMonarda stulosa Wild Bergamot 150mmPenstemon digitalis Foxglove Beardtongue 150mmPhysostegia virginiana Obedient Plant 150mmRudbeckia hirta Black-eyed Susan 150mm

Verbena simplex Slender Vervain 100-150mm Verbena stricta Hoary Vervain 150mm Veronicastrum virgin icum Culver’s Root 150mm

Non-Native Woody Plants (Continued)


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Non-Native Plants - Full SunBotanical Name Common Name Min. DepthAster tararicus ‘Jindai’ Dwarf Tatarian Aster 150mmAster tararicus Tartarian Aster 150mm

Bergenia Cordifolia Heart-leaved Bergenia 150mmCentaurea Montana Mountain Bluet 150mmCerastium tomentosum Snow-in-summer 100-150mmCoreopsis tripteris Tall Tickseed 100-150mmCoreopsis verticillata Thread-leaved Coreopsis 100-150mmDianthus deltoides Maiden Pinks 100-150mmCampion (Silene) Moss Pinks 100-150mmEchinacea purpurea Purple Coneower 100-150mmEchinops ritro Globe Thistle 150mmEuphorbia Crown-of-thorns 100-150mmGeranium maculatum Wild Geranium 100-150mmGeranium psilosteum Armenian Cranesbill 100-150mmGeranium pratense Meadow Cranesbill 100-150mmGeranium sanguineum Bloody Geranium 100-150mmGaillardia grandiora Blanket ower 100-150mmGeum Avens 100-150mmHemerocallis Daylily 100-150mmHosta sieboldiana (Sun Loving Hostas) 150mmIris germanica German Iris 100-150mmIris setosa Dwarf Arctic Iris 100-150mmLavandula angustifolia English Lavender 100-150mm

Leucanthemum X superbum Shasta Daisy 100-150mmNepeta X faassenii Catmint 100-150mmPhlox subulata Creeping Phlox 100-150mmRudbeckia Goldsturm Coneower 100-150mmSalvia X sylvestris Sage 100-150mmSedum album Carpet Stonecrop 100-150mmSedum ellacombianum Sedum ellacombianum 100-150mmSedum ewersii Pink Mongolian Stonecrop 100-150mmSedum hybrid ‘Autumn Joy’ Autumn Joy 100-150mmSedum kamschaticum Sedum kamschaticum 100-150mm


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Sedum sexangulare Tasteless Stonecrop 100-150mmSedum spectabilis Showy Stonecrop 150mmSolidago sphacelata Dwarf Goldenrod 150mm

X Solidaster luteus Solidaster 100-150mmSedum spurium Dragon’s Blood 100-150mmStachys byzantina Lamb’s ears 100-150mmThymus serphyllum Creeping Thyme 100-150mmThymus X citriodorus Lemon Thyme 100-150mm

Veronica longifolia Long-leaved Speedwell 100-150mm Veronica noveboracensis Ironweed 100-150mm

Non-Native Plants - Full Sun (Continued)


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Noxious Weeds (Ont. Regulation 1096 – Weed Control Act)

Item Common Name Botanical Name1. Barberry, common Berberis vulgaris L.2. Buckthorn, European Rhamnus cathartica L.3. Carrot, wild Daucus carota L.4. Colt’s-foot Tussilago farfara L.5. Dodder spp. Cuscuta spp.5.1 Giant Hogweed Heracleum mantegazzianum6. Goat’s-beard spp. Tragopogon spp.7. Hemlock, poison Conium maculatum L.8. Johnson grass Sorghum halepense (L.) Persoon9. Knapweed spp. Centaurea spp.

10. Milkweed spp. Asclepias spp.11. Poison-ivy Rhus radicans L.12. Proso millet, black-seeded Panicum miliaceum L.

(black-seeded biotype)13. Ragweed spp. Ambrosia spp.14. Rocket, yellow Barbarea spp.15. Sow-thistle, annual, perennial Sonchus spp.16. Spurge, Cypress Euphorbia cyparissias L.

17. Spurge, leafy Euphorbia esula L. (complex)18. Thistle, bull Cirsium vulgare (Savi) Tenore19. Thistle, Canada Cirsium arvense (L.) Scopoli20. Thistle, nodding, spp. Carduus spp.21. Thistle, Russian Salsola pestifer Aven Nelson22. Thistle, Scotch Onopordum acanthium L.23. Vetchling, tuberous Lathyrus tuberosus L.

http://www.e-laws.gov.on.ca/html/regs/english/elaws_regs_901096_e.htm

Appendix B: Plant Species to Avoid

City of Toronto Bylaw No.583-2009 492-9 L states that vegetation ona green roof shall not include any noxious weeds as de ned in OntarioRegulation 1096 under the Weed Control Act (see table below). In additionthe following plant species also should be avoided:

• Medicago spp . (Black Medick),Capsella sp . (Shepherd’s Purse),Cerastium sp . (Chickweeds) will each grow exponentially and thenundergo massive die-off during periods of drought. Each set largenumbers of seeds and have incredible spread.

• Digitaria spp . (Crabgrasses),Alliaria sp . (Garlic Mustards),Ambrosia sp .(Ragweed) all very drought tolerant, but highly competitive and spread

very fast.

• Chenopodium album (Lamb’s Quarter) - very drought tolerant -staying green when everything else is brown - but sets many seedsand spreads fast.


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Common Name Scientific Name Species whose caterpillars use this plant• gerardia Gerardia spp. Common Buckeye• • wild sunflower Helianthus spp. Silvery Checkerspot• butter-and-eggs Linaria vulgaris Common Buckeye• wild lupine Lupinus perennis Wild Indigo Duskywing, Karner Blue• • apple Malus spp. White Admiral/Red-spotted Purple• alfalfa Medicago sativa Clouded Sulphur, Orange Sulphur, Eastern Tailed-Blue• sweet-clover Melilotus spp. Orange Sulphur, Summer Azure, Silvery Blue• panic grass Panicum spp. Tawny-edged Skipper, Northern Broken-Dash, Hobomok Skipper• parsley Petroselinum crispum Black Swallowtail• timothy Phleum pra tense European Skipper, Long Dash• ninebark Physocarpus opulifolius Spring Azure, Summer Azure• English plantain Plantago lanceolata Common Buckeye• native pine Pinus spp. Eastern Pine Elfin• bluegrass Poa pratensis Long Dash, Hobomok Skipper, Common Ringlet, Little Wood-Satyr• native poplar Populus spp. Dreamy Duskywing, Canadian Tiger Swallowtail, Red-spotted Purple/White Admiral, Viceroy• • cherry/plum Prunus spp. Canadian Tiger Swallowtail, Eastern Tiger Swallowtail, Coral

Hairstreak, Striped Hairstreak, Spring Azure, Cherry Gall Azure,Red-spotted Purple/White Admiral

• hoptree Ptelea trifoliata Giant Swallowtail• • oak Quercus spp. Juvenal’s Duskywing, Edwards’ Hairstreak, Banded Hairstreak• black locust Robinia pseudoacacia Silver-spotted Skipper• curled dock Rumex crispus American Copper, Bronze Copper• sheep sorrel Rumex acetosella American Copper• rue Ruta graveolens Black Swallowtail, Giant Swallowtail• • willow Salix spp. Dreamy Duskywing, Red-spotted Purple/White Admiral, Viceroy, Compton Tortoiseshell, Mourning Cloak, Green Comma• sassafras Sassafras albidum Spicebush Swallowtail• wild mustard Sinapis arvensis spp. Mustard White• • aster Symphyotrichum spp. Pearl Crescent, Northern Crescent• clover Trifolium spp. Clouded Sulphur, Eastern Tailed-Blue• • elm Ulmus spp. Mourning Cloak, Question Mark, Eastern Comma• • nettle Urtica spp., Laportea spp. Red Admiral, Milbert’s Tortoiseshell , Question Mark, Eastern Comma• • viburnum Viburnum spp. Spring Azure, Summer Azure• • vetch Vicia spp. Clouded Sulphur, Orange Sulphur, Eastern Tailed-Blue, Silvery Blue• • violet Viola spp. Variegated Fritillary, Silver-bordered Fritillary, Meadow Fritillary,

Great Spangled Fritillary• pansy Viola wittrockiana Variegated Fritillary• prickly ash Zanthoxylum americanum Giant Swallowtail


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TORONTO CITY PLANNING ZONING BYLAW AND ENVIRONMENTAL PLANNING

Nectar Plants

SPRING FLOWERING (March – early June) Common Name Scientific Name• • serviceberry Amelanchier spp.• • dogwood Cornus spp.• • • hawthorn Crataegus spp.• fleabane Erigeron spp.• wild strawberry Fragaria virginiana• dame’s rocket Hesperis matronalis• • apple Malus spp.• ninebark Physocarpus opulifolius • • • buttercup Ranunculus spp.• • blackberry/raspberry Rubus spp.• elderberry Sambucus spp.• cup plant Silphium perfoliatum• lilac Syringa spp.• dandelion Taraxacum officinale• coltsfoot Tussilago farfara• • thyme Thymus spp.• • • viburnum Viburnum spp.• • violet Viola spp. • catnip Nepeta cataria

• • phlox Phlox spp.• • cinquefoil Potentilla spp.• • • buttercup Ranunculus spp.• • prairie coneflower Ratibida spp.• staghorn sumac Rhus typhina• • black-eyed Susan Rudbeckia hirta• • tall coneflower Rudbeckia laciniata• • brown-eyed coneflower Rudbeckia triloba• rue Ruta graveolens• salvia Salvia spp.• scabiosa Scabiosa spp.•

clover Trifolium spp.• heliotrope Valeriana officinalis• • vervain Verbena spp.• • ironweed Vernonia spp.• zinnia Zinnia spp.

SUMMER FLOWERING (June – August) Common Name Scientific Name• chives Allium schoenoprasum• dogbane Apocynum spp.• • milkweed Asclepias spp.• butterfly bush Buddleja davidii • virgin’s bower Clematis virginiana• coreopsis Coreopsis spp.• purple coneflower Echinacea spp.• • Joe-Pye weed Eupatorium purpureum• heliotrope Heliotropium spp.• lantana Lantana spp.• • blazing star Liatris spp.• purple loosestrife Lythrum salicana• alfalfa Medicago sativa• sweet-clover Melilotus spp.• • • mint Mentha spp.• bee-balm Monarda didyma• wild bergamot Monarda fistulosa

FALL FLOWERING (September – October) Common Name Scientific Name• spotted knapweed Centaurea maculosa• • boneset Eupatorium perfoliatum• showy stonecrop Sedum spectabile• goldenrod Solidago spp.• • aster Symphyotrichum spp.

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city of toronto guidelines for biodiverse green roofs (2013)

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