Words and Photos by Marisa Thompson

Nikita’s Gift persimmons (Diospyros virginiana x kaki hybrid) after dark a few days before harvest at NMSU Agricultural Science Center in Los Lunas on November 7, 2022.

What’s your favorite tree?

Is it the magnolia you napped under on a hot summer day on vacation in Madrid? Is it the live oak that Edgar Allen Poe wrote about while stationed in your hometown? Or the shrubby fig tree outside your grandmother’s kitchen window? Is it the one that creates your favorite flower, or the one that harbors your favorite birds? Or is it the one currently shading your car in the driveway? Perhaps you have a favorite species of tree, like the cottonwoods in the Rio Grande bosque or the bigtooth maples in the Manzano Mountains.

My answer is a resounding “yes” to all of these.

But selecting a tree for your yard now is about finding your future favorite tree, not replicating a favorite from the past. You’ll never fall in love and grow old together if your new tree isn’t healthy. And it will thrive into maturity only if it is well suited to your landscape conditions.

Cold hardiness, heat hardiness, drought tolerance, and size are all primary considerations when drafting a wish list and strategizing care in the long term. And the long term is what we’re growing for—not only for our future selves but so that the next resident inherits a healthy tree they can maintain, one that might even become their kid’s childhood favorite.

(Sidenote spoiler alert for those seeking a fast-growing tree: very generally, trees that grow fast die young. With so much energy spent on aboveground growth, less is spent on healthy roots, sturdy limbs, or a strong immune system.)

In terms of tree requirements, cold hardiness may be the most straightforward. Just about every landscape plant species and variety has an established USDA plant hardiness rating that is readily googleable, if not listed on the nursery tag. To find the USDA plant hardiness zone for your area, visit planthardiness.ars.usda.gov. If the tree you’re considering is cold hardy down to the same zone in your yard or lower, you can rest assured that the likeliness of a frosty death is extremely low. So a bigtooth maple (Acer grandidentatum), cold hardy down to zone 4, will be just fine after a rough January in the City Different. But blue palo verde (Parkinsonia florida) is documented to be cold hardy only down to zone 8 (10°F to 20°F), so this tree that’s common in Tucson and becoming more common in El Paso is not expected to withstand the cold temperatures experienced in an average Santa Fe winter.

Heat hardiness isn’t quite as clear, but has become extremely important. By 2050 (less than thirty years away!), high temperatures in the Albuquerque area are expected to resemble the current highs in Las Cruces or El Paso, and by the end of the century (less than eighty years away), they’ll be closer to the highs currently experienced in Tucson. For trees and other perennial plants to live and thrive as long as possible, we need to consider how cold hardy they are this decade and how heat hardy they will be in the warmer decades to come. Handily, two recent reports created by folks at The Nature Conservancy, New Mexico State Forestry, and a host of other local collaborators dig into recommended climate-ready trees for the Albuquerque area and the five climate zones of New Mexico (both reports can be found on the Tree New Mexico website, treenm.org/partners-and-resources/some-recommended-trees-for-planting).

Now let’s touch on the question of size. “Right tree, right place” is not just a mantra of arborists worldwide—it is the mantra. Considering how big a tree will be at maturity is crucial. The bigger the tree, the bigger the necessary canopy and rooting area. Without sufficient lateral root room, trees become stressed. With stress comes a compromised immune system and a higher susceptibility to all sorts of insect and disease pressures.

On top of size, space, and hardiness, when people ask me, “What’s the best tree for my yard?” the following questions jump to mind.

How do you plan to water the area surrounding this new tree?
Unfortunately, in our warming world and lasting drought, even desert plants native to our region require supplemental irrigation as they become established, and thereafter. So a watering method and plan are a must. This doesn’t have to be a fancy irrigation system; irrigating the entire root area and beyond can be done with a garden hose or even a five-gallon bucket. If you have both, drill small holes in the bottom of the bucket so that water dribbles out slowly after being filled, then move the bucket a few times around the tree canopy dripline to be sure the roots are saturated in all directions. As a general rule, water to a depth of about two feet and allow the soil to dry out between soaks so roots have access to oxygen. A thick layer of plant-based mulch will help maintain soil moisture levels. A minimum mulch depth of four inches is also optimal for the control of many annual weeds in the soil seed bank. 

Left: Mexican buckeye pod.  Right: Bigtooth maple (Acer grandidentatum). 

How attached are you to only planting a tree?
Even if your niche is small, a cluster of smaller or medium-sized plants offers diversity, both aesthetically and ecologically. Instead of a huge single tree, consider a small climate-ready tree, a compact shrub, three small ornamental grasses, and a few perennial flowers, all grouped together.  

How often do you walk by? And who else might enjoy it?
Dramatic fall foliage displays make the Texas red oak (Quercus buckleyi) and Chinese pistache (Pistacia chinensis) great showpiece trees when placed in highly visible areas, seen from inside your home or out. If this is a spot you and your family pass frequently or will sit under, consider something that attracts hummingbirds, like a desert willow (Chilopsis linearis). Female New Mexico olive trees (Forestiera neomexicana) provide berries for backyard birds, and the bright yellow fall color is beautiful too. Speaking of color, in early spring, when most of the other trees are still dormant, the pinky-purple flowers of redbuds (Cercis species) are extraordinary. If you plant one that’s visible to neighbors, be sure to remember the variety, because they will want to know.    

Which native plants could you incorporate into this area?
Native species offer a wealth of ecosystem services for beneficial insects, birds, and other fun wildlife. Resources abound. The Native Plant Society of New Mexico website (npsnm.org) offers helpful lists with plant descriptions and tips for urban landscapes. The New Mexico State University Extension publication Perennial Plants for Pollinators (pubs.nmsu.edu/_h/H182.pdf) suggests flowering plants that attract native bees. And Valle de Oro’s ABQ Backyard Refuge Program offers ideas for native trees as well as other plants.

How long have you lived there?
It wasn’t until after six months at my new house, when the windy season hit, that my front entryway became a gathering spot for leaf litter and random lightweight trash, mostly Doritos and Funyuns bags. My point is that it’s good to get to know your space and how you want to use it before making decisions you might regret. If I had planted roses by my front door, like I originally planned, I’d be quarreling with thorny stems each time I tried to clean up.

Do you need this tree to provide shade? And, if so, do you have enough room?
 Remember the arborists’ mantra? In a smaller space, you might be better off with a shade structure adorned with beautiful climbing vines. Of course, growing trees for shade is worth the time it takes to get there. But in a restricted area, there’s not enough rooting space to support a large shade tree. And remember what stress from root restrictions invites? Secondary problems like pests and diseases. 

Deciding on the tree species is the big first step toward a long, lasting friendship. The next steps include choosing healthy specimens at a nursery, avoiding common planting mistakes and soil problems, and strategizing care. Find links to all of these topics by searching my blog for the word edible (nmsudesertblooms.blogspot.com).   

You’re not alone on this landscaping journey. Reach out to local experts if you need help along the way. 

I wonder what my new favorite tree will be. As author Lorene Edwards Forkner said, “Planting trees means you believe in tomorrow.” 

Afganski pomegranate in Los Lunas.

Smart Xeriscaping Lists & Tree sources

Check out your local botanical gardens, nurseries, and garden centers too!

Keep in mind that every plant list has some drawbacks or, at least, constraints. Long lists can be cumbersome, but short lists often limit species diversity, which is important for healthy ecosystems. And, sadly, few lists give priority to native species. Whittle down a shorter wish list of your own—one that includes native species cross-referenced on multiple local resource lists.

Marisa Thompson
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Marisa Thompson is New Mexico State University's Extension Urban Horticulture Specialist, responsible for active extension and research programs supporting sustainable horticulture in New Mexico. In addition to studying landscape mulches and tomatoes, her research interests include abiotic plant stressors like wind, cold, heat, drought, and soil compaction. She writes a weekly gardening column, Southwest Yard & Garden, which is published in newspapers and magazines across the state and on her blog. Find her on social media @NMdesertblooms.