We’re all aware that low precipitation prevails in most of our Southwest communities. We have received 4.4 inches of rain by mid-May this year— and it shows. But there’s more to the survival picture for plants in Southwest landscapes. Altitude, wind, and heat challenges each interact with our dry conditions in one way or another.
All told, the Southwest is the hottest and driest region in the United States. Climate change has added more heat and drier conditions in the southernmost areas. So, when you think about helping plants survive our heat, you also have to think about how our geography and climate help or hurt the heat problem and learn to work around as much as you humanly can.
The low desert socks it to summer landscapes. Gardeners can help plants survive by choosing native or desert-adapted plants, providing shade, especially in the afternoons, and watering plants deeply. These and other tips are in our free booklet for subscribers: Get Your SW Garden Ready for the Heat (see below). All of these strategies help. But if you want to grow food, which isn’t native or adapted, here are some additional tips.
Tips: Edible Gardening in the Hot Southwest
- Adjust planting times to match your area, using local sources when possible. Most people plant tomatoes by early to middle May. Not so in the hot desert. Check our blog, our contributors’ blogs, local extension offices and master gardener groups or local nurseries for the schedules in your area.
- Grow what you love in the best conditions you can give the plant. Celery is a foolish thing to grow in a desert climate, but you can get good tomato yields and all peppers (sweet and spicy) love heat. If you want lettuce and other greens, grow them cooler times or indoors in summer.
- Invest in shade fabric for newly planted ornamentals, tomatoes, or other plants that wilt in heat. If that is more expense or more fabric than you need, just get creative. Stake down an old woven lawn chair to block hot afternoon sun. Or use an old window screen or maybe a sun shade from your car for a few days, just until your young plant toughens up. Just be sure to give the plant airflow (or it will heat up more) and secure whatever shade you use from wind.
At higher altitudes of the Southwest, it doesn’t get as hot as in low deserts, but it can reach 100 degrees in our higher deserts in summer and still freeze often in winter. We get wild 24-hour temperature swings. All of these argue in favor of native plants and paying some extra attention throughout seasons, or even a single day, to the garden and plant health.
Altitude typically cools the air, but it increases solar radiation. And middle and low-desert gardeners are high enough above sea level to get some of altitude’s effects when combined with high heat. For every 1,000 meters altitude increases, UV radiation levels jump 10% to 12%. So, even at only 3,000 feet above sea level, UV rays are 10% stronger, affecting your skin and your plants.
Just like the effect altitude has on people—dehydration, rapid sunburn—plants in high deserts can wilt and suffer from the combinations of drought, heat and altitude. At higher altitudes, transpiration (water movement through a plant and eventual evaporation) occurs at higher rates, exhausting a plant’s available water. In addition, growing season length is shorter for high-altitude gardeners because of cool nights.
Tips for Gardening in High-Altitude, Dry Regions
- Monitor and protect plants as best as possible, adding warmth at night for new plantings or seeds and shade as needed in peak daytime heat.
- Choose short-season edibles for best success. High-altitude growing seasons are too short for most melons and winter squashes, and too cool for peppers. Smaller and short-season hybrid tomatoes will ripen most years.
- Enjoy native wildflowers or perennials. Many of the wildflowers, called ephemerals because of their short life cycles, sprout after a good rain and give you spring or summer color. They might or might not show up again the next year, depending on conditions.
- Accept that growing plants from seed might not work as well in high-altitude areas with short seasons. By the time nighttime temperatures warm the soil enough to sprout flower seeds, the plants are ready for growth spurts just as summer afternoons begin to blaze.
I don’t have to tell anyone living in the Southwest about wind. It’s worse in some open plains, foothills and low deserts than in others, but we all deal with it. Our strong, dry winds can wick water from soil and leaves, adding to drought and heat effects. Wind also damages plant structures, breaking entire branches. We can’t stop the wind, but we can provide breaks and protect young plants in particular from the wind. Just like drought, wind stresses plants, making it hard to grow healthy roots.
Tips for Coping with Wind in the Garden
- Plant wind-susceptible plants where they get a wind break from structures (buildings, fences) or other plants. The wind can whip around, but most of us know the prevailing wind direction for our area (such as from southwest to northeast).
- Usually, the crest of a hill or slope is the windiest spot. Plant on the hillside itself, on a south-facing slope when possible.
- If you have a bad wind problem affecting a tree or shrub, you can build a temporary wall with fabric such as burlap or garden shade cloth. Just be sure the posts you use to hold the fabric are sturdily planted or a heavy wind could knock the entire “wall” over and damage your plant more.
- It is not a good idea to stake trees, but young ones might need some protection the first year. Brace the tree trunk with a soft cloth or tubing. We run rope through pieces cut from old garden hoses to protect the trees. Rope or wire can destroy the trunk.
- Harden off new plants, especially vegetables like tomatoes and peppers, by setting them out in morning breezes first, getting them used to wind (and sun) a little at a time for up to a week if you can.
- Add a mini-greenhouse over tender young plants, and stake it thoroughly. We protect small plants from wind with 5-gallon buckets with the bottom cut out and held by a wooden or rebar stake. Just place the open bucket over the plant and drive a stake down on the edge the same direction as your wind typical wind gusts. These are easy to lift off and put back on if wind picks up.
Learn More About Gardening in Heat
Our free booklet on Southwest Gardening and Heat is available only to our email subscribers. If you already have subscribed, check last week’s or this week’s email for the link to your copy. If you’re new to Southwest Gardening, sign up for our newsletter here and get your free booklet.
Teresa Odle is the editor of African Violet Magazine, a freelance editor for BobVila.com, and author of a blog on low-water gardening in the Southwest. Teresa trained as a Master Gardener in Albuquerque, N.M. She grew up in the Phoenix area, and has lived in the mountains of northern New Mexico. Teresa and her husband now attempt to manage four acres of land in zone 6B of southeastern New Mexico. The land includes a large xeric garden, herbs and vegetables, and a small orchard that borders the Rio Ruidoso in Lincoln County. Teresa’s blog, Gardening in a Drought, won a 2016 national award for best writing in digital media from the Association for Garden Communicators.