Issue: February 15, 2003

Broom dalea plants

Question:

I have seen some grayish-green shrubs along the highway south of Albuquerque. Right now they just look like sticks, but last summer they had lots of small purple flowers. What is this? Are these plants available in the nurseries? Tom B. Albuquerque

Answer:

From your description, I think you have seen the plant called broom dalea (Psorothamnis scoporia). This is one of our native plants that is very well adapted to our hot, dry environment. Broom dalea grows in the deep sandy soils of the mesa regions around Albuquerque, northward to the Jemez and southward to El Paso. At maturity, it is often 3 feet high and 3 to 4 feet across. It is a useful plant in dry areas where it will receive little or no supplemental irrigation. In arroyos, its twiggy growth is good for slowing water flow and reducing erosion. Broom dalea grows best in deep, well-drained soils that are common to the mesas. It does not grow well in the valley soils if they contain clay and hold too much water.

Bees will actively forage broom dalea and produce an excellent honey. Flower production is greatest in years with good monsoon rains.

It is listed among the plants sold by some native plant and xeriscape-oriented nurseries. Call the nurseries to see if it is available.

Rocky Mtn. zinnia

Question:

What is Rocky Mountain zinnia? Is it a good plant for New Mexico landscapes?

Answer:

Rocky Mountain zinnia (also called Prairie or Plains zinnia) is a member of the daisy, or sunflower family that is very well adapted to our xeric gardening environment. Its scientific name is Zinnia grandiflora, so it is indeed a zinnia but not like the zinnia commonly sold as a garden plant. The Rocky Mountain zinnia is a perennial and doesn't need to be planted each year. It is not as subject to powdery mildew fungus problems and is much lower growing. Its flowers are yellow, small, and produced in large numbers in late spring, then it continues to produce scattered flowers through the summer until frost.

As a perennial, it has a tendency to spread but is not weedy. It needs very little water and will die if over-watered. This zinnia will grow best in well-drained soils. In winter, it turns brown and can be left in place to protect the soil from wind erosion. It may be trimmed back to near ground level before growth begins in the spring.

This is an excellent plant for our water conserving landscapes.

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Send gardening questions to Southwest Yard and Garden, Attn: Dr. Marisa Thompson at desertblooms@nmsu.edu or at https://www.facebook.com/DesertBloomsNM/. Please include your county Extension Agent (aces.nmsu.edu/county) and your county of residence with your question!

For more gardening information, visit the NMSU Extension Horticulture page: desertblooms@nmsu.edu.

Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, office: 505-865-7340, ext. 113.