By Scott Calhoun
Some people are in denial, but we do have a winter in the desert Southwest. At night it typically dips below freezing for two weeks or so each winter in cities such as Tucson, and it’s much colder, on more days, at higher elevations. Many popular tropicals go dormant, or require some protection (see below) to make it to spring. However, a host of winter growers make the cool season interesting. What follows are my plant suggestions and tips for winter gardening.
Many desert wildflowers germinate in fall and winter, grow over the cool months, and pay big dividends come spring. Even short warm spells can germinate seeds and produce vibrant blooms such as the succulent lupine featured above. Plant the following from seed to liven up your winter and early spring garden:
- Desert globemallow (Sphaeralcea ambigua)
- Mexican gold poppy (Escholtzia Mexicana)
- Parry’s penstemon (Penstemon parryi)
- Succulent lupine (Lupinus succulentus)
Protect the Fragile Ones
In low-desert cities, such as Phoenix, Tucson, and Las Vegas, the first freeze typically comes around early December. Popular ornamental plants grown in the desert, such as bougainvillea, pictured right, need frost protection. Bougainvillea loves heat but often loses its leaves in winter, depending on the severity of frosts. Cover with frost cloth to protect branches from frost damage.
Many aloe family plants can withstand some frost, but do not bloom until the following year, if their bloom stalks freeze. For this reason, when hard freezes are forecast, cover the following plants and other tropicals with frost cloth or bring them indoors (if possible):
- Young citrus trees
- Young palo blanco (Acacia willardiana) trees
- Aloe species
- Totem pole cactus (Pachycereus schottii f. monstrosus)
- Mexican fencepost cactus (Pachycereus marginatus)
Mediterranean and California Favorites
Mediterranean climate plants and most coastal California natives (like the Cleveland sage, listed below) are winter growers. The following ornamentals make a nice show over the cool months and into spring, and you can easily plant them over the entire cool season. Plants such as gopher plant, pictured right, are among the earliest bloomers, often adding color in February.
- Cleveland sage (Salvia clevelandii)
- Gopher plant (Euphorbia rigida)
- Moroccan mound (Euphorbia resinifera)
- Tuscan Blue rosemary (Rosmarinus officinalis ‘Tuscan Blue’)
- Shrubby germander (Teucrium fruticans)
Bulbs for Zing
Liven up your holiday pots with bulbs. For winter gardening, bulbs such as Portuguese squill, pictured right, can add interest in an otherwise garden downtime. Plant them in pots beginning in fall. You can plant multiple bulb crops in succession for uninterrupted blooming. They look great in pots on patios, and indoors in bright, sunny windows. Try the following:
- Amaryillis species
- Electric hyacinth (Lachenalia aloides var. quadricolor)
- Fresia species
- Portuguese squill (Scilla peruviana)
Adjust Your Watering Schedule
Many desert gardeners use programmable timers to turn drip irrigation systems on and off. Dialing back the watering frequency in winter saves water and keeps your plants healthy. In the true winter months (December–February), established desert-adapted trees need watering only every 30–60 days; established desert-adapted shrubs, 30–45 days; and established desert-adapted ground covers, perennials, and vines, 21–45 days.