Desert Blooms

Southwest Yard & Garden by Dr. Marisa Thompson Zinnia showing off both disk and ray flowers at the NMSU Agricultural Science Center in Los Lunas. Photo credit M. Thompson     Question: I have a large monarch butterfly garden, and I gathered zinnia seed heads to plant next spring. Zinnia seeds appear to have two distinct morphologies. The ray flower seed is shield-shaped and the disk flower seed is smaller and flatter. Which of the seeds is viable? I have researched and found some who say only the ray seed, some say only the disk seed, and some say both. Please let me know which zinnia seed is most viable and why. -           Tim P., New Mexico Answer: I know exactly what you mean. I’ve had this question before myself. Zinnias were one of my first garden successes when I moved to Las Cruces in 2009. I too gathered the seed heads and I too wondered which part was the true seed that sho...

Southwest Yard & Garden by Dr. Marisa Thompson Clumps of the mistletoe parasite stand out like a sore thumb when deciduous  trees are otherwise bare.  Photo credit pixabay.com. Question: What trees are resistant to mistletoe? -         John Allen, NMSU Extension Agriculture Agent & Program Director, Socorro County Answer:  OK, no one really calls mistletoe “the kiss of death” as I did in this week’s column title. That’s my attempt to grab readers by the eyeballs. Mistletoes don’t tend to kill their tree hosts, but it is possible, and they certainly can do harm, leaving the host plants more vulnerable to other stressors. The genus name for true mistletoe is Phoradendron , which means “tree thief.” Mistletoe is usually green or at least a puke-green color. Winter is a good time to detect it in deciduous trees because the tree leaves have dropped and the mistletoe is temporarily exposed. Greenness is a clue that mis...

Southwest Yard & Garden by Dr. Marisa Thompson Locally grown in Santa Fe. Check poinsettia labels to see if they're #NMTrue too! Photo credit M. Thompson Question: I love the poinsettias I bought this year, but one is already starting to droop pretty badly. How do I keep them looking good through the season? -         Elizabeth S., Santa Fe One trick to keep leggy stalks from bending over is to tie them midway with a single piece of crochet thread. Photo credit M. Thompson. Answer: Did you know you can purchase locally-grown poinsettias at plant nurseries across the state? I interviewed poinsettia growers in Albuquerque, Santa Fe, Las Cruces, Radium Springs, and Estancia to find out more about poinsettia production in New Mexico, how to get my hands on one (or a few) this season, and how to take care of them at home. The City of Albuquerque Parks and Recreation Department grows its own poinsettias for holiday displays...

Southwest Yard & Garden by Dr. Marisa Thompson Waxy white clumps produced by cochineal scale on cholla. Photo credit S. Moran. Cholla infested with cochineal scale. Photo credit S. Moran. Question:  What’s the white cottony stuff growing on my cholla cactus? And should I do anything about it? -         Albuquerque resident via Bernalillo County Extension Horticulture Agent, Sara Moran Answer: Although it looks like cotton fibers, that stuff is actually a fine wax produced by adult cochineal scale insects, and little black specks may be their nymphs. It’s common around these parts on cholla ( Cylindropuntia spp.) and prickly pear ( Opuntia spp.) cacti. The similar-looking white beards on other cacti, like the Peruvian old man ( Espostoa lanata ) and Peruvian old lady ( Espostoa melanostele ), are normal, healthy modified tissues, not an insect product. The white waxy coating made by cochineal scale on landscape chollas and ...

Southwest Yard & Garden by Dr. Marisa Thompson These cottonwoods in Albuquerque skipped the glorious golden stage of fall color altogether. 2018. Photo credit Wes  Brittenham. Question: Why are some cottonwood trees turning brown rather than yellow this fall? Sometimes a portion of the tree (often the lower portion) turns brown while the crown does turn yellow. I think I have seen this in other years, but this fall it seems more pronounced. Is it weather related? Moisture? -         Wes B., Albuquerque, NM Answer: Explanations for why leaves change color the way they do can be related to the species or cultivar, temperature fluctuations, seasonal day length changes, and potentially the soil moisture levels too. A general rule is that while temperature tends to affect the intensity of leaf color, it’s the shorter days and longer nights that trigger overall color change. Chlorophyll is the green pigment that starts the process of...

Southwest Yard & Garden by Dr. Marisa Thompson Tree growth is slowing as temperatures fall (photo credit M. Thompson). Question: I’ve seen conflicting advice online on whether or not to fertilize trees now to promote healthy root growth. -         Camille R., Albuquerque Answer: Don’t fertilize anything in fall because we want growth to slow with dormancy, and the salts in fertilizer will either just sit there and be unhealthy for soil/roots or actively damage roots. When carefully selected and applied, fertilizers can help boost a plant that’s already putting on a flush of top growth, like in the spring and early summer. In our areas, applying fertilizer now may extend late-season growth, and that new tender growth is particularly susceptible to cold injury. Water, applied low and slow to the whole root zone, is the best “fertilizer” to help trees through the winter, plus a cozy, fibrous mulch layer on top of the soil. Depending...

Southwest Yard & Garden by Dr. Marisa Thompson Lilac inflorescence. Photo credit John O’Neill, Wikimedia Commons. Question: I've got some spindly lilac bushes. Should I cut them back now or wait for spring? How can I make them grow fuller? -         Lisa W., Santa Fe Answer: Good news—you can wait even longer. For maximum flowering effect, keep your clippers in their scabbard until after the lilac flowers have senesced (faded). Lilac bushes bear flowers on last year’s growth, so if you prune in the late summer or fall when branch growth slows in preparation for dormancy, you’ll likely diminish—or extinguish—spring blooming. This is also true for other early spring bloomers, like forsythia and cherry trees. In last week’s column , we learned about the bearing habits of fruit trees and how stressful environmental events, like drought or typhoons, can trigger plants to flower at the wrong time. A friend from Wilmington, North Carolina...