Tucson lies in the heart of the Sonoran Desert where summers are serious business. In 2024, a record-breaking 112 days brought temperatures over 100 degrees.
We crave shade here, but where there’s shade in Tucson there’s apt to be affluence. In contrast, seven of the 10 hottest neighborhoods are on the city’s Southside, one of the poorest parts of town. On a summer day, temperatures in the hottest Southside neighborhoods can exceed citywide averages by 7 to 8 degrees. When compared to the Catalina Foothills—one of our metro area’s most affluent regions—that disparity can run as high as 12 degrees.
This isn’t unique to Tucson. A recent study averaged seven years of data to come up with mean temperatures for Tucson and 19 other Southwest cities. The study found that on an average summer day, temperatures were significantly hotter in poorer and more Latino neighborhoods than in richer, whiter ones.
So, to help cool this desert city of 542,000 people, some of my fellow Tucsonans have been busy planting trees. They’re working to achieve an ambitious goal: one million trees planted by 2030.
One Saturday, my friend Mandy and I joined a handful of other adults and a bunch of high schoolers to help plant trees in a modest neighborhood on Tucson’s Southside. Luckily, the digging conditions we encountered in the first yard were the worst—when our arms were still fresh.
“Caliche,” sighed Lenore, a fellow volunteer pushing 70 but still doggedly moving dirt. Caliche is a notorious feature in the Southwest—soil cemented by calcium carbonate. The first time I faced caliche was trying to plant a tree in my own yard, where a hard white layer had formed. You have to break through that hard layer before planting anything.
Lenore was mistaken—it wasn’t caliche—but the soil was compacted and dry. We’d scrape away one or two inches, then launch another round with the digging bar to break up more. Teenagers across the yard weren’t faring any better.
At long last, we dug deep enough to plant two native hackberry trees that in time will offer food for birds and pollinators, as well as shade. We watered them in, then headed down the street to the next house.
“I’m tired,” Mandy admitted. “Are you tired?”. I wasn’t, but I would’ve been if I’d been digging solo.
The second yard, like the first, was bare, but this time the ground was considerably softer. While we dug, two women came out with their friendly husky to cheer us on. Working as a team, we planted two native desert willows.
The third yard was easier still. The young couple who bought the house six months ago had watered the spots—hallelujah!—where we then planted a desert willow and a red push pistache. He and the other homeowners had agreed to keep watering their new trees, particularly before the monsoon rains (hopefully) arrive in late summer and until the trees become established, at which point the desert-adapted trees can largely fend for themselves.
These trees are “a promise to future generations” for shade, health and prosperity, said Mayor Regina Romero — Tucson’s first-ever female mayor and first Hispanic mayor in 150 years.
“Climate change waits for no one,” the mayor said. “Without a livable community, we have no Tucson.”
My friend Mandy and I got involved through the NeighborWoods Tree Planting program, which operates under the nonprofit Tucson Clean & Beautiful. It works closely with the city and is funded entirely by the state through the Inflation Reduction Act, with money guaranteed for one more year.
The mayor launched the Tucson Million Trees initiative in 2020 by planting a tree in her own yard. Five years later, 150,000 trees are in the ground. While new plantings are encouraged everywhere, the NeighborWoods program invests heavily in neighborhoods that are particularly hot.
Fliers distributed to neighborhoods offer a short list of low-water use, mostly native trees for planting, including palo verde, desert ironwood and velvet mesquite. The program offers up to three free trees per yard—homeowner’s choice—plus free labor to put them in the ground.
The morning I volunteered, folks planted 101 trees. I personally helped plant three of them. It’s a long way to reach one million, but I’ll be back. We need all the shade we can get.
Karen Mockler lives and writes in Tucson, Arizona and is a contributor to Writers on the Range, writersontherange.org, an independent nonprofit dedicated to spurring lively conversation about the West.
