no. 7.229

Xeriscaping: Trees and Shrubs

by J.E. Klett and C.R Wilson1 (7/09)

Quick Facts...

  • Select trees and shrubs for xeric landscapes based on both adaptation to Colorado’s climate and the ability to prosper in reduced water situations.
  • Assess site soil, drainage and exposure before selecting trees and shrubs.
  • Apply adequate water during the first years of plant establishment, then gradually reduce irrigation.
  • Woody plants are a long-term investment.

Plants that will prosper in Colorado’s harsh climate without benefit of ample irrigation require careful selection. This is especially true of woody trees and shrubs that are more expensive investments than herbaceous plants, both in terms of money and time to grow.

As a long-term investment, select and plant trees and shrubs only after careful evaluation of the site’s soil, drainage and exposure. While some xeric plants tolerate reduced water, they may not function well in soils low in oxygen. Many of the state’s dense clay soils have minimal room to accommodate enough water and oxygen to meet plant root needs. Preparing soils by adding organic amendments prior to planting can often overcome water-oxygen concerns during initial establishment. Reduced water using trees and shrubs are best planted in areas separate from lawns unless lawns are also a reduced water use type. Regardless of how durable woody plants are for survival in xeric conditions, many plants need at least two growing seasons to establish. Water during establishment, then gradually reduce irrigation.

Adequate soil drainage plays an important role in preventing soils from water logging which leaves no room for oxygen. Conduct a subsoil drainage test by digging an 18 x 18 inch hole, filling it with water and timing how long it takes to drain. Water that stands in the hole for more than 30 minutes indicates poor drainage. If amending the soil doesn’t solve drainage problems drain tile or planting on berms (mounds) of well-drained soil brought to the site may be other solutions. Berms should be built to a minimum height of 24 inches.

Some trees and shrubs may perform poorly in hot south or windy west exposures and would be better sited in cooler east or north exposure.

The following list of durable trees and shrubs will prosper in reduced water situations.

 

Table 1: Large trees for xeriscapes.
Plant name Height/
Spread (ft)
Growth Rate Comments

Acer negundo


Boxelder

 

40 x 30
F
Fast growing shade tree for harsh sites. ‘Sensation’ is a seedless male tree that doesn’t attract boxelder bugs, yellow to red-orange fall color.

Catalpa speciosa
Western catalpa

50 x 35
M
Large, heart-shaped leaves with fragrant white flowers in June followed by long, thin seed pods.
Celtis occidentalis Common hackberry
45 x 45
M
Irregular habit when young
maturing to rounded crown. Distinctive knobby bark. Trees shed leaves during drought. Red-purple berries
Gleditsia triacanthos inermis
Thornless honeylocust
35 to 55 x 25 to 45
M
Many varieties available that vary in size.
Thornless and many varieties podless. Fine textured foliage turns yellow in fall.

Gymnocladus dioicus
Kentucky coffeetree

55 x 35
S
Large compound leaves. Females bear seedpods that remain on trees through winter. Ridged bark, stout branches and coarse winter texture.

Juniperus scopulorum
Rocky Mountain juniper

30 x 15
S
Native evergreen with blue-green foliage. Berry-like cones that
are dark blue in the second year. Prefers full sun. Many varieties.
Koelreuteria paniculata
Goldenrain tree
30 x 30
M
Compound leaves emerge red turn to green. Yellow clusters of
flowers in summer are followed by lantern-like fruit.
Pinus aristata
Bristlecone pine
35 x 20
S
Native evergreen with dark pine green needles bearing white
flecks.
Pinus ponderosa
Ponderosa pine
60 x 30
M
Native evergreen with long, yellow-green needles in clusters
of 2 or 3. Plate-like bark is cinnamon to dark brown.
Quercus macrocarpa
Bur oak
70 x 60
M
Fiddle-shaped leaves borne on stout, corky-ridged branches. Adapts to alkaline soils. Distinctive fringed acorns.
Robinia pseudoacacia
Purple Robe’ locust
35 x 25
M
Compound leaves emerge with purple tint. Dark purple fragrant flowers in May to June. Very susceptible to locust borer.

 
Table 2: Small trees for xeriscapes.
Plant name Height
Spread (ft)
Growth Rate Comments
Acer grandidentatum Bigtooth maple (Wasatch maple)
25 x 25
S Small tree or large shrub. Tolerant of dry and alkaline soils.
Dark green leaves turn red-yellow fall color.
Acer tataricum Tatarian maple
20 x 20
M
Single or multi-stemmed tree. Pink to red winged seeds in summer with yellow fall color. Tolerates alkaline soils. ‘Hot Wings’ is a newer variety with distinctive red fruits and reddish fall color.
Crataegus ambigua
Russian hawthorn
20 x 15
M
Lightly thorned tree with finely cut, glossy green leaves. Clusters of white flowers followed by bright red fruits.
Crataegus crus-galli inermis
Thornless cockspur hawthorn
15 x 15
M
Thornless horizontal branches bear glossy leaves, white flowers and persistent red fruit.
Pinus edulis,
Pinyon pine
25 x 15
S-M
Native, bushy evergreen with gray-green, stiff needles. Bares small, rounded cones with edible seeds.
Prunus armeniaca
Apricot
20 x 20
M
Glossy, heart-shaped leaves cover a broad, spreading tree. Early, white-pink blossoms, rarely bares fruit due to spring frosts.
Pyrus ussuriensis Ussurian pear
25 x 20
M
White flower clusters produced before dark green leaves that turn yellow in fall. ‘Prairie Gem’ is a dense tree with an upright, oval form and strong branching.

Quercus gambelii
Gambel oak

20 x 12
M
Native large shrub or small tree with irregular spreading branches dark green leaves and tan acorns.
Table 3: Shrubs for xeriscapes.
Plant name Height
Spread (ft)
Flower color/month
Comments

Amorpha canescens
Leadplant

3 x 4
Purple/Jul – Aug
Silver-gray foliage, fine texture, fruit not important

Artemisia cana
Silver artemesia

5 x 3
Yellow/Aug-Sept
Stiff, upright branches, slender gray leaves, native of Colorado
mountain meadows

Artemisia tridentata
Big sage

10 x 6
Yellow/Aug-Sept
Silver, aromatic foliage; bark shreds with age, native
Atriplex canescens
Saltbush
5x 4
Yellow/Jul-Aug
Gray green leaves, upright spreading form, four winged fruit on female plants, tolerates alkaline soil
Berberis thunbergii
Japanese barberry
3 x 5
Yellow-Apr-May
Dwarf and purple leafed forms available, site in good light, single spines, red persistent fruit

Berberis x ‘Tara’ Emerald Carousel ™
Emerald Carousel barberry

4 x 5
Yellow-Apr-May
Rounded form, arching branches, prefers sun, red persistent
fruit, orange to red fall foliage color appears early and lasts long, good for alkaline soils
Buddleia alternifolia 'Argentea’ - SilverFountain butterflybush
10 x 8
Violet/May-Jun
Arching form, silver-gray foliage, fine texture, flowers on old wood, attracts butterflies, extremely hardy
Caragana arborescens Siberian peashrub
12 x 10
Yellow/May - Jun
Upright, olive-green branches, bears small spines, produces pea--like pods, tolerant of poor soils and windy sites
Caryopteris x clandonensis
Blue mist spirea
4 x 4
Blue-violet to purple /Jul-Sep
Silver green foliage, upright branches, persistent dry tan fruit,
attracts bees
Cercocarpus ledifolius- Curlleaf mountain-mahogany
20 x 12

Cream yellow/Apr-May, not showy

Large shrub or small upright tree, evergreen foliage, seeds
with twisted, feathery tails; foothills native
Cercocarpus montanus
8 x 6
Cream yellow/Apr-May, not showy
Large shrub or small upright tree, evergreen foliage, seeds

Chamaebatiaria millefolium
Fernbush

5 x 6
White/Jun-Jul
Fern-like gray green leaves, fine-textured and aromatic, rounded
form

Chrysothamnus spp.
Rabbitbrush

6 x 6
Yellow/Aug – Sep
Open, rounded form, green to white stems, silvery green leaves,
reseeds
Cowania mexicana
Cliff rose
6 x 6
Creamy White/Apr-May
Upright semi-evergreen shrub, gray-green leaves, feathery seed tails
Elaeagnus umbellata Autumn-olive
15 x 15
Silvery flowers/Apr-May
Large spreading shrub, green leaves with silvery undersides,
May may sucker and spread
Ephedra equisetina Bluestem jointfir
4 x 5
Not important
Upright leafless stems are blue-green year round, red berries
midsummer on female plants
Fallugia paradoxa
Apache plume
5 x 5
White/May – Aug
Small leaves, fine-textured, whitish stems, rose-colored feathery- tailed seeds, some suckering
Fendlera rupicola
Cliff fendlerbush
5 x 5
White/Jun
Glossy foliage, new reddish bark turns gray with age, upright
irregular growth, fragrant flowers
Forestiera neomexicana New Mexican privet
12 x 10
Yellow/Apr
Erect arching branches, rounded form, blue-black fruit on female,
yellow fall color
Hippophae rhamnoides Sea-buckthorn
18 x 12
Yellow/Mar-Apr
Upright, spreading shrub with slender thorns, narrow silvery
leaves, orange fruit on females persists into winter
Holodiscus dumosus
Rock spirea
4 x 4
White/May – Jun
Upright spreading habit, fine-textured foliage turns red in fall,
rust colored seedheads in fall
Juniperus spp.
Juniper
Many sizes
Not important
Available in many foliage colors, forms and textures, see
Evergreen Shrubs fact sheet 7.414.
Ligustrum vulgare ‘Cheyenne' ,
Cheyenne privet
10 x 6
White/Jun-Jul
Upright, rapid grower, dark green foliage, black fruit in late
summer into winter, used for hedges, fragrant flowers
Pinus mugo
Mugo pine
Many sizes
Not important
Many forms and growth habts, see Evergreen shrubs fact sheet
7.414
Potentilla fruticosa
Cinquefoil (potentilla)
4 x 4
Yellow/White/Pink


Jun- frost
Compact, speading and upright forms, varied foliage color, full
sun for best flowering
Prunus besseyi
Sand cherry
6 x 6
White/Apr – May
Upright rounded form, gray green leaves, purplish black fruit,
red fall color
Rhus glabra cismontana
Smooth sumac
6 x 6
Yellow/Jun - Jul
Rounded, suckering shrub, red fall color, fuzzy maroon
persistent fruit
Rhus trilobata
Threeleaf sumac
6 x 6
Yellow, May
Dense rounded shrub, three-lobed leaves turn orange to red in fall, some red fruit
Rosa woodsii
Native pink rose
6 x 6
Pink/June
Arching branches, red-brown stems with loose prickles, red hips persistent, orange to red fall color
Rubus deliciosus
Boulder raspberry
6 x 6
White/May-Jun
Slender arching branches form vase-shaped habit, small purple fruit in late summer
Shepherdia argentea Silver buffaloberry
15 x 12
Yellow/Apr-May
Dense spreading branches with spines, silvery-green leaves,
yellow to orange-red berries on female plants
Symphoricarpos albusSnowberry
4 x 4
White/Jun
Arching, spreading habit with blue-green foliage, white blue-green foliage, white berries persist, suckers
Symphoricarpos x chenaultii ‘Hancock’ Hancock coralberry
3 x 6
Pink/Jun
Spreading growth habit with blue-green fine textured foliage,
red berries persist. excellent ground cover
Syringa vulgaris
Common lilac
15 x 12
Purple/Apr – May
Upright vase-shaped form, heart-shaped blue-green leaves
Viburnum lantana
Wayfaring tree viburnum
12 x 10
White/May
Broad rounded form, dark green, leathery foliage with deep set veins, crimson fruit turns black in fall, burgundy red fall color

1J.E. Klett, Colorado State University Extension landscape horticulturist and professor, department of horticulture and landscape architecture; C. R. Wilson, Extension horticulture agent, Denver County. Revised from original fact sheet authored by J.R. Feucht. 10/99. Reviewed 7/09.

Colorado State University, U.S. Department of Agriculture and Colorado counties cooperating. Extension programs are available to all without discrimination. No endorsement of products mentioned is intended nor is criticism implied of products not mentioned.

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