“A lot of cacti can live where they do—not because it’s hot and dry, but because the soil doesn’t hold water,” says Leo J. Chance, of Colorado Springs, Colo., author of Cacti and Succulents for Cold Climates: 274 Outstanding Species for Challenging Conditions.
Depending on your climate, here are tips for planting and growing a cactus outdoors:
Plant selection. Good choices for cooler climates include Escobarias, Coryphantha, Echinocereus and Opuntia (commonly called prickly pears). Opuntia Fragilis is a small prickly pear that grows as far north as Alberta, Canada, and Coombes Winter Glow is a prickly pear that turns purple or cranberry-colored in the winter.
Even in dry climates, not all cactuses thrive, so pay attention to each plant’s needs. When selecting plants, look for an even-colored cactus without bruises and check the plant’s flesh for firmness. “You want to feel nice firm flesh,” says Daniel Armenta, horticulturist at the Arizona-Sonora Desert Museum in Tucson, who suggests using a pencil with an eraser head to touch the plant to avoid pricking your finger on a spine.
Planting. Because of its shallow root system, a cactus is susceptible to rot. Thus, make sure to plant in a location where the base can dry out. Chance suggests elevating the plant on a berm, placing extra gravel underneath, or setting the cactus on rocks. “Take two rocks, place them together and plant in- between so the base of the plant is sitting on top but the roots are in the soil and you’ve raised the plant,” he says.
The best soil is loamy. Mix with pea-size gravel to improve drainage. “The wetter your situation, the more gravel you should mix in,” Chance says. “A 50-50 mix will cause the soil to dry better.”
Care. A cactus needs occasional water. Water well, then let the soil dry completely, especially for new plants. “Once established, they can go through drought without showing too many signs of stress. They may not bloom well next year, but they won’t die,” Chance says.
For desert climates, some cactuses don’t fare well in excessive direct sunlight, but can handle light better if there’s moisture in the air. “You can plant them to the eastern side of a tree or house so in the afternoon they’ll get some shade,” Armenta says.
Overwintering. Snow cover creates a protective microclimate, in which it’s warmer beneath the snow than the air above. Snowless days are more threatening when the mercury dips below freezing for an extended period. If the cactus was planted during the last few months, Chancecovers it during sub-freezing temperatures. Armenta suggests covering tender new growth with Styrofoam cups or, for larger plants, with old bed sheets or towels.