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