plant selection: low water landscaping. plant selection for low water landscapes - historically,...
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Plant Selection: Low Water Landscaping
Plant Selection for Low Water Landscapes
-Historically, plants selected from a limited “palette” for specific aesthetic and some functional traits (i.e. shade)
-Low water landscapes require detailed knowledge about adaptation during selection
Selection Criteria: Ornamental
• Type– Tree=>specimens,
shade, screening, architectural effect; the “ceiling”
– Shrubs=> specimens, screening, color; the “walls”
– Perennials/bunch grasses/ground cover=> color, surface cover, texture
Selection Criteria: Environmental Traits
• Cold tolerance-either or• Sun/shade requirements-
how well does plant grow• Pruning needs-nuisance
issues• Soil requirements-
drainage, fertility• Water requirements-
drought tolerance
• Our landscapes derived from northern Europe– High rainfall, natural grass, grazed swards– Imbedded trees, fringed with shrubs, annuals
Why We Have What We Have
• Imported across the US, including the SW deserts
Why We Have What We Have• Current paradigm:
– English landscape with extensive use of turfgrass across country
• Works well– The grass sward works
well for recreation and park areas
– Often used mindlessly as the sole option in surface cover
• Most non turf plants also derived from high rainfall climates
Why We Have What We Have
– Trees are popular, and big trees only found where there is high rainfall; mesic climates. Attractive shrubs also from mesic climates
– Woody plants from mesic climates easy to propagate and grow in nurseries, landscapes
– Annuals chosen for color
Components of Low Water Landscaping: Design
• Practical design aspects of low water landscaping– Non uniform plant layout– Hardscape that does not require irrigation– Spacing that provides plants with more rooting volume
• Qualitative design aspects– Creating and honoring
a sense of place– Recreating or being
inspired by natural patterns
Components of Low Water Landscaping: Plant Material
• Practical aspects: choosing drought adapted plant material– By designing in space
and non-uniformity, any plant can be more drought tolerant
• Qualitative aspects– Creating (reinforcing) a
sense of place– Telling a story and giving
meaning
Intermountain West Native Plants: Sources
• Again, using drought-adapted plants suited to particularly dry conditions requires careful knowledge of a particular species’ requirements
• Adaptation can vary within a species depending on geographic source of seed
Intermountain West Native Plants: Sources
• Cultivars- (CULTivated VARiety) are selected from within a species for certain traits, mostly ornamental but sometimes environmental;
• Seed stock-plants grown from seed, genetically – Genetically uniform plants creates uniform look and
behavior, but may be susceptible to disease attack=monoculture
– Genetically diverse plants closer to natural state, but may be uneven in terms of appearance
Intermountain West Native Plants: Selecting
• Tremendous craving for new plants in horticultural circles, both cultivars and species
• Most of US has been exploited for horticultural plant material;
• Intermountain West is relatively undiscovered regarding horticultural potential
– Utah has 3,000+ species, many perennial wild flowers; undiscovered horticultural treasure trove
Intermountain West Native Plants: Sources of Problems
• LA’s, landscapers who think they know what they are doing, but don’t– Interpret natives/low water=day lillies, dogwood– Using native low water plant indiscriminately
regarding how individual plants work together, availability
Intermountain West Native Plants: Selecting
• Plants are difficult for general public to make sense; native and drought adaptation even more difficult
• 40 best Utah native species for promotion have been selected: Plant Select
– Few trees, since few trees are native
– Mostly shrubs and perennial wildflowers
– Most generally available, relative easy to produce and will stay alive in landscapes
A word about watering
New transplants of even very drought-hardy species need weekly wateringuntil root systems become established.
Establishment can take a month to a full season, depending on species and time of transplanting.
Grasses and perennials establish quickly, while shrubs and trees generally take longer.
Very low water use – deep-water 1-2 times a summer during drought
Low water use – deep-water every 4-6 weeks
Medium water use – deep-water every 2-4 weeks
High water use – deep-water every 1-2 weeks
After Establishment