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Master Gardener Journal  


S P E C I A L   F E A T U R E



Desert-Adapted Evergreen Trees

by Lisa Dubas,
Master Gardener Intern


On virtually every street in Phoenix, you can spot trees that are entirely too large for the yards they occupy. When a landscaper or nursery employee suggests Ficus nitida for your small front yard, or a Chilean mesquite to be planted in a narrow space, they're overlooking the amount of pruning it will take to keep the trees a manageable size for their allotted spaces.

Here are a few things to keep in mind when selecting the best tree for a small yard:

Consider the mature height and width of the tree and plant accordingly. Don't place a tree that grows to a diameter of 20 feet within 5 feet of your home's foundation.

Don't plant thorny trees near active areas or walkways.

Some desert trees have a multiple trunk structure by nature . Pruning to one central trunk may make the tree unstable.

If you have to stake, do so for a maximum of two years. A tree staked longer than that may need to be staked its entire life.

Shallow watering can cause salt buildup in the root zone. To avoid this, water to a depth of 3 feet around the outer canopy of the tree.

The following is a list of six popular desert-adapted trees that work where space is limited. Each one is small (maximum 20-foot height by 20-foot width) and evergreen (meaning they lose a few leaves at a time, instead of all at once).


    MULGA ACACIA
    (Acacia aneura)
  • Full sun
  • Hardy to 20°F
  • Prune in October
  • Puffy yellow flowers in 3 or 4 cycles per year, but mostly in spring/summer
  • Narrow, compact growth structure
  • Medium growth rate
  • No thorns
  • Mature example on display at the Desert Botanical Garden in Phoenix
    GUAJILLO ACACIA
    (Acacia berlandieri)
  • Full sun
  • Hardy to 15°F-20°F
  • Prune in June
  • White puffball flowers from February to May (seedpods in summer)
  • Tendency toward multiple trunk structure
  • Slow-growing
  • Slightly thorny
    HARDY SWEET ACACIA
    (Acacia smallii)
  • Full sun
  • Hardy to 10°F-15°F
  • Prune after spring bloom
  • Plant any time of year
  • Golden puffball flowers from late fall to March
  • Fast-growing
  • Very thorny!
  • Mature example on display at the Desert Botanical Garden in Phoenix
  • Beneficial to native wildlife

Caesalpnia cacalaco
    CASCALOTE(above)
    (Caesalpinia cacalaco)
  • Full sun
  • Hardy to 20°F
  • Prune after winter bloom
  • Yellow flower clusters from September through February
  • Fast-growing
  • Very thorny
  • Plant in a warm winter location (such as a south-facing wall)

Lysiloma watsonii thornberri
    FEATHER TREE
    (Lysiloma watsonii thornberi)
  • Full sun
  • Hardy to 25°F
  • Prune in January
  • Plant in spring
  • Small white puffball flowers from May to June (flat seedpods follow bloom)
  • Medium growth rate
  • Not thorny
  • Mature example on display at the Desert Botanical Garden in Phoenix
  • Sensitive to the cold
  • Too much water may lead to chlorosis
  • Beneficial to native wildflower

Texas Ebony
    TEXAS EBONY
    (Pithecellobium flexicaule)
  • Full sun, accepts some shade
  • Hardy to 20°F
  • Plant in spring or fall
  • Prune in late winter
  • Puffy cream-colored flowers in spring and summer
  • Slow growth rate
  • Very thorny
  • Don't plant near electrical lines
  • Mature example on display at the Desert Botanical Garden in Phoenix
  • Beneficial to native wildlife
Resources:
"Desert Landscaping for Beginners" 2001.
Arizona Master Gardener Press,
Phoenix, AZ.

Duffield, Mary Rose and Warren D. Jones.
Plants for Dry Climates: How to Select, Grow , and Enjoy.
2001.
Perseus Publishing, Cambridge, MA.

Johnson, Eric A.
Pruning, Planting & Care.
1997. Ironwood Press, Tucson , AZ.

"Guide to Arizona Desert Shade Trees."
The Arizona Community Tree Council, Inc. and the Desert Botanical Garden.


Photography: Candice Sherrill




Maricopa County Master Gardener Volunteer Information
Last Updated January 25, 2003
Author: Lucy K. Bradley, Extension Agent Urban Horticulture, University of Arizona Cooperative Extension, Maricopa County
© 1997 The University of Arizona, College of Agriculture and Life Sciences, Cooperative Extension in Maricopa County
Comments to Maricopa-hort@ag.arizona.edu 4341 E. Broadway Road, Phoenix, AZ 85040,
Voice: (602) 470-8086 ext. 301, Fax (602) 470-8092