Cactus Village Community

IT’S DECEMBER—JACK FROST MAY BE VISITING!

Jul 27, 2003

Although Arizona newcomers may scoff at the concern, those of us who have spent even a few winters m Phoenix know that the weather does, in fact, get cold, and frosts can occur. According to the University of Arizona College of Agriculture Extension Center in Maricopa County (seems like there should be an acronym for that, but I couldn?’t fmd one), the average first frost date in Phoenix is December 12; the average last frost date is February 7, which means we have a two-month period for potential frost damage to our precious plants.

What to do, what to do? The first, and obvious, suggestion is to select frost-tolerant plants and place them in protected locations?—western and southern exposures, near rocks, patios and brick walls which tend to collect and retain the heat of day, and full-sun versus shaded areas. Keep plants well watered, but also keep the moisture level as even as possible. Be aware of overprotection, however, as experts tell us plants become more frost-resistant if they?’re kept somewhat hardened to cold weather.

When the temperature drops, cover plants completely with cloth or paper, but not plastic, from the top of the plant to the ground, without any openings for heat to escape. Coverings should be removed every morning when the temperature underneath warms to 50 degrees unless special commercially-made frost cloths are used. Many of these can be left in place for extended periods of time without damaging the plant.

Young citrus are frequently protected by loosely wrapping the trunks with multiple layers of cloth or weather-resistant paper from the ground to the level of the lower branches, and can be left on through mid-February. A trickle of running water to the ground at the tree?’s base for up to three nights (not longer, as the risks could outweigh the benefits at that point) may offer additional protection, as the water in its cooling process will release energy in the form of heat.

Methods not recommended are fires which (remember high school physics?) send hot air up above the plants, sucking cold air from nearby areas; mulch, as it prevents the warming of soil; chemicals; and smudge pots.

And, finally, a note about frost damage should it occur:

Don?’t be too eager to trim away the unsightly areas. Pruning can, in fact, stimulate new growth that could be vulnerable to further or late frosts. Be patient. The damage may not ultimately be as bad as it initially seems, and new growth may occur in tissue you thought was dead. When new growth starts in the spring, prune away! . . . ☻