Plant Selection

Landscape Management

Plant Selection for Low Water Landscapes

• Requires more knowledge of plants than conventional approaches– Historically, plants selected

from a limited “palette” for specific aesthetic and some functional traits (i.e. shade)

– Lack of adaptation to given set of conditions made up for by management input

• 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

– =Provenance of a seed source– Provenance critical in revegetating natural

sites with most adapted plant material; using seed collected from that site

Intermountain West Native Plants: Sources

• Cultivars- (CULTivated VARiety) are selected from within a species for certain traits, mostly ornamental but sometimes environmental; most of the time clonally propagated=genetically uniform

• 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

Provenance• Example bigtooth maple

(Acer grandidentatum)

• Found in widely scattered locations in SW up to SE Idaho

• Southern populations likely to be less cold hardy as northern populations

• Cultivars likely to be selected from northern provenance for most cold tolerance

• Fall color varies within a population and can be selected for

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; many native plant groups around the country

• Intermountain West is relatively undiscovered regarding horticultural potential– Current introductions from Intermountain West (IMW)

mostly riparian and montane species– IMW plants from dry communities harder to grow– Utah has 3,000+ species, many perennial wild flowers;

undiscovered horticultural treasure trove

Intermountain West Native Plants: Sources of Problems

• Proposing alternatives to existing way we landscape threatens some people and groups– Undermine perceived cultural values, sense of

control

• 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

• HOWEVER, how to make sense of all those species?

• Plants are difficult for general public to make sense; native and drought adaptation even more difficult

• USU and Intermountain Native Plant Growers Association selected 40 best Utah native species for promotion

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– Similar to plant introduction programs around the country

Co-sponsors:

Utah State University Center for Water-Efficient Landscaping

Utah Botanic CenterUtah Native Plant Society

A tagging and educational program promoting the use of water-wise native plants

in Intermountain landscapes

Intermountain Native Plant Growers Association

The program includes:

Picture plant tags for 40 species of Intermountain native plants, available for purchase at cost from INPGA by

wholesale and retail nurseries

Plant signs with color photos and cultural information for use in retail nursery display

A full-color promotional posterI

Information brochures available for free distribution through:

USU extension offices water conservancy district offices

other interested organizations

Public education

Plant Selection

The 40 species included in Utah’s Choice for 2003were selected by a panel of horticultural experts representing the sponsoring organizations.

All the species are native to the Intermountain West.

They were chosen on the basis of outstanding beauty, flexibility, ease of culture, and availability.

Not all the species meet all these criteria, but all meet the criterion of outstanding beauty.

Dozens more species could qualify for Utah’s Choice—we plan to add many more species in coming years.

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

Intermountain West Native Plants: Selecting

• 40 plants is limiting, and many good ones to choose from

• USU/Utah Botanical Center working on second waterwise book that takes top 100 IMW/Utah native plants, and shows how to design with these plants – More affordable– Class project will be used as an example in

the book

Intermountain West Native Plants: Selecting

• Trees: 16 species, 2 large conifers,7 medium/smallish trees, 7 shrubby small trees

• Succulents: 2 yuccas• Vines: 2• Shrubs: 26, 10 evergreen• Ground covers: 5 evergreen species• Perennial wildflowers: 40, including 10

penstemons• Bunch grasses: 9, including buffalograss as an

honorary native species

Intermountain West Native Plants: Selecting

• These top 100 do not exhaust the potential of IMW native species as landscape plants– Some may drop, others added to make the list

100+

• The second book and list of 100 will further spur nurseries to produce these plants, and you to design and use them – Knowledge of these plants and how they can

be used is a powerful tool