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When to Prune: Considerations Galore

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Southwest Yard and Garden By Dr. Marisa Thompson, NMSU Extension Horticulture Specialist

Links to related columns: 
Pruning Do's and Don'ts
Rose Pruning
Lilac Pruning
Pomegranate Pruning
Fruit Thinning (late spring/early summer)
Scroll down for more pruning resource links!
Question: When is the right time to prune ornamental and fruit trees?
- Weary gardeners across the state


Answer: Well, you’re not going to be surprised at this answer: It just depends.
What are your reasons for pruning? Are your trees grown for their beautiful blooms? If so, do they bloom before leaves start to appear? Trees like redbuds and crabapples and shrubs like lilac and forsythia flower before they leaf out, and that’s a clue that the flowers emerge from buds growing on older growth. If you prune too much you’ll lose out on this season’s flush of color. It makes more sense to prune those just after they’ve bloomed.
On the other hand, if you’re wanting to reduce the growth of a young tree because branches are get…

Inspiration from the Extension Master Gardener Program

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Southwest Yard and Garden By Marisa Thompson

Lady’s mantle (Alchemilla mollis) in Asheville, North Carolina (photographed last May) provides a beautiful example of guttation, which is the formation of water droplets on leaf margins and is not dew. Photo credits M. Thompson.

In the past month I’ve had a great time teaching “basic botany and plant identification” to Extension Master Gardener Trainee classes in a Doña Ana, Santa Fe, and Taos Counties. From the NMSU Extension Master Gardener (EMG) website: “Each year, EMG chapters throughout NM produce knowledgeable gardeners who enjoy assisting their local Cooperative Extension Service office in providing accurate, research-based gardening information to county residents. Within the programmatic structure of the Extension Master Gardener Program is a curriculum focused on the fundamentals of good horticultural and biological land management practices. Classes are held at varying times of the year (depending on the county) in an effort to pr…

Skinny Tomato Plants & Too Tall Amaryllis

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Southwest Yard and Garden Written by Dr. Curtis Smith (Photos by Dr. Marisa Thompson)
2 reprints Skinny Tomato Plants Started Indoors - February 23, 1997 Amaryllis Flowers Too Tall - February 11, 2000

Skinny Tomato Plants Started Indoors By Dr. Curtis Smith Reprint from February 23, 1997 Question: I started some tomato plants inside this winter so I could move them into the garden as soon as the weather allowed. I started them on top of the refrigerator like the books said, but they are skinny and keep falling over. They don't look as good as the plants I bought last year. What is wrong?
Answer: The books recommend starting the seedlings on top of a refrigerator because in days when we didn't keep our homes too warm, the top of the refrigerator was warm. Many plants germinate from seed more quickly if the room in which they are kept is cool but the soil is warm. The refrigerator kept the soil warmer. Once the seeds have germinated and the new plants can be seen, they should be moved int…

Soil Searching: Amendments Are No Longer Recommended

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Southwest Yard & Garden by Dr. Marisa Thompson partial reprint from October 2018

Frosty cottonwood leaves add a nice layer on top of several inches of shredded woodchip mulch. Photo credit M. Thompson.
Question: Should I add fertilizer or amendments to the soil when planting landscape plants in my garden?     -Gardeners All Over New Mexico Answer: The short answer is no. And the long-term answer is an even stronger no. Soil amendments are materials that are worked into the soil with the intention of improving soil physical qualities. The trouble is it’s just not that simple. As City of Las Cruces Community Forester Jimmy Zabriskie said when I asked if he ever recommends using soil amendments when planting a tree, “Save your money for mulch.” Mulch is material that sits on top of the soil, providing an insulation layer that helps control soil temperature, retain moisture, and suppress weeds.
Shredded woodchip mulch helps soil hold moisture and insulates plant roots on a frosty November …

Protect Your Trunks: Sunscald Kills

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Southwest Yard & Garden (Follow-Up to Last Week’s “Transplanting Plum Trees” Column)

by Dr. Marisa Thompson


Just after last week’s column on transplanting 8-year-old plum trees was published, City of Las Cruces Community Forester Jimmy Zabriskie contacted me about another important consideration: sunscald. Zabriskie pointed out that care should be taken to be sure transplants are oriented in the same direction in their new spot as they were when they were originally planted. The concern here is that the southwest side of the trunk may have already been hardened and is better able to withstand afternoon sun during winter months. If a tree is inadvertently rotated, there could be a higher risk of getting winter sunscald (aka southwest injury) on that tender side. Zabriskie also notes that orientation should be considered when transplanting other ornamental plants like shrubs, cacti, and agaves.
I’m glad Zabriskie brought this up because I’m concerned that winter sunscald is a much bigge…

Transplanting Plum Trees

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Southwest Yard & Garden by Dr. Marisa Thompson & guest contributor Dr. Curtis Smith

TUNE IN NEXT WEEK FOR A FOLLOW-UP COLUMN WITH ADDITIONAL TRANSPLANTING SUGGESTIONS FROM CITY OF LAS CRUCES URBAN FORESTER JIMMY ZABRISKIE! ‘Stanley’ plums at the NMSU Agricultural Science Center at Los Lunas in September 20, 2018. Photo credits M. Thompson.
Question: I had an individual call with questions about plum trees she needs to transplant. When is the best time to transplant? And what is the best method? -Cheyenne Law, Guadalupe County Extension Agent

Answer: This is a great question. The short answer is “when the trees are fully dormant,” so any time before they flower or leaf out in the spring. But I’d like to know more before giving a full answer. It really depends on how old and how big the trees are. I’d also like to know why these trees are being transplanted, where they’re going (what’s the soil type), and if they currently have any signs of stress (specifically borers).
After conta…

Pruning Dos and Don’ts

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Southwest Yard & Garden by Dr. Marisa Thompson Pruning Dos and Don’ts

SCROLL DOWN FOR A LIST OF PRUNING WORKSHOPS ACROSS NEW MEXICO IN 2020!



Question: I get stressed this time of year because I know it is almost time to prune our landscape trees. Can you give some tips on how to prune with confidence? -Geri T., Albuquerque Answer: The task of pruning used to stress me out too. Every winter I’d watch a few YouTube videos, take some deep breaths, and then put pruning off for another time because I felt that my skills weren’t good enough to—cut it. It is actually good that you are reluctant to jump outside and whack away without an action plan. While some pruning may be necessary for safety and canopy manipulation, any time we cut into a tree we are creating a potential site for infection. One form of chronic tree torture is pruning annually just because. Recommended pruning techniques have changed—and continue to change—with new research. In 2017, the American National Standards Institute …