S P E C I A L   F E A T U R E

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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

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)

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
(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