Posts

Deciding Factors for Deciduous Color: All the Leaves are Brown, and the Sky is Turquoise

Image
Southwest Yard & Garden by Dr. Marisa Thompson 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 photosynthesis by helping convert sunlight, carbon dioxide, and water into sugars that travel through the plant to other branches or roots where the plant uses them as food. Normally, chlorophyll…

Fertilizer Pros and Woes

Image
Southwest Yard & Garden by Dr. Marisa 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 on how warm this winter is in your region, how much snow we get (fingers crossed!), your soil type, the tree species, and the age of the…

Lilac It or Not: Hold Off On Pruning Until Flowers Fade

Image
Southwest Yard & Garden by Dr. Marisa Thompson 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 told me this past weekend that many of the area’s dogwoods, redbuds, Bradford pears, and azaleas are blooming out of sync, and…

Fruit Trees Flowering at the Wrong Times: Late Bloomers? Or Are These Flowers Precocious?

Image
Southwest Yard & Garden by Dr. Marisa Thompson
Question: Do you know why my Ranier cherry tree is blooming now (September 30)? It doesn’t look so good, but earlier this year it produced a decent amount of cherries. -Stacia G., Albuquerque, NM Answer: I came across Stacia’s question on a gardening Facebook page with photos of her flowering cherry tree. Fellow plant-loving Facebooker and grower in Edgewood, Ken Koger, provided a great response post: “Very common on fruit trees that have been stressed from lack of water. They basically go into a semi-dormant state, and then when monsoons hit with suddenly lower temps, water to the roots, and higher humidity they come out of the dormant state and first thing they do is bloom, just like in spring.” Koger went on to recommend watering deeper and out beyond the small tree’s dripline, where the majority of the hard-working, water absorbing roots are expected to grow. He also suggested a fat layer of wood-chip mulch, which made me happy as a …

Green with Tomato Envy

Image
Southwest Yard & Garden by Dr. Marisa Thompson
Question: What should I do with all of these green tomatoes? -Yours Truly, Los Lunas, NM
Answer: As first frosts snapped across the state in the last few weeks, gardeners have been sharing photos of final harvests, many with green tomatoes piled high. There is also much discussion about how to ripen them and what to do with them. If you’re a seed saver, you may want the fruits to ripen to maturity. The difference between being mature and ripe is that “maturity” refers to seed viability and ripeness is the most favorable state for consumption or use. Ripeness, then, is partly dependent on personal taste and the intended market. Many fruits (like grapes, pomegranates, and citrus) get more flavorful and achieve higher quality if allowed to ripen before being picked. Others, though, are often picked when they’re technically mature but not completely ripe, so that fewer rot during transport (e.g., bananas, pears, avocados). The difference has…

Seasonal Deadheading Decisions: Deadheading Works on Some Flowers Better than Others, but Timing is Everything

Image
Southwest Yard & Garden by Dr. Marisa Thompson Question: Does deadheading marigolds encourage new flowers? -Jeannie O., Truth or Consequences Answer: I’ve often wondered this myself. Many flowering plants, like coreopsis, roses, yarrow, catmint, and marigolds respond very well to deadheading and are worth the effort. Others, like portulaca, begonias, and impatiens, may not need deadheading because their flowers just fall off naturally or the new flowers conceal the old. I had trouble finding lists of flowers that should never be deadheaded. It is more crucial to watch the calendar. If the second flush of flowers will have time to develop and bloom before frost, deadheading may be a good idea. As Dr. Curtis Smith, retired NMSU Extension Horticulture Specialist, pointed out when I asked for his input earlier this week, “Our summer annuals and our perennials are going to die soon when frost arrives, or go dormant, so deadheading them now is not really necessary.  In Central and Northern…