Regional Gardening Reports :: National Gardening Association

In the Garden:
Southwestern Deserts
February, 2007
Regional Report

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This aloe turns color in cold weather.

The Big Chill

My neighborhood has been hard hit by 2007's colder-than-average freezing temperatures. I hauled enough container plants indoors to turn my entryway into an atrium, much to the cat's delight and visitors' peril. Even so, a few containers that I thought would be okay outdoors got hit. I am now the owner of frost-damaged green and variegated elephant's food (Portulacaria afra) plants, which references list as hardy to 25 degrees F. They were located near a protected wall, which I thought would radiate sufficient heat to keep them safe. Obviously, I should have filled the guest bathroom with plants as well!

I'm also sad about the condition of an Aloe vanbalenii, which I purchased recently in a 1-gallon container from a Tucson nursery. It was the only one they had, and I snatched it up, cackling at my good luck while planning ahead to all the pups it would produce to pot up for friends. I'd been looking for this aloe for years because I just love the unusual coloration. In cold weather, they turn a rich, rusty hue. Sometimes only the toothed margins turn color, sometimes the entire leaf. The Desert Botanical Garden in Phoenix showcased a clump of these aloe that caught visitors' eyes in the succulent house. My other aloes seem to have survived, but the A. vanbalenii is decidedly mushy. It didn't have time to establish in its new home before this string of cold nights. Sigh.

Cold-tender tropical plants, such as bougainvillea, natal plum, and ficus trees that my neighborhood HOA maintains, really took a beating. At quick glance, the now-brown ficus (F. nitida) canopies resemble autumn trees before leaf drop.

Don't Prune Frost Damage
Winter isn't over yet! No matter how unsightly the frost damage may appear, don't trim it off. The dead foliage acts as an insulating buffer to protect live tissue during future frosts. Another potential outcome of pruning too early is removing more plant tissue than necessary. Oftentimes, damage looks worse than it is. Wait until new green growth starts to pop as temperatures warm in March or early April. Then cut back dead stems to that new growth.

Protect from Further Frost Damage
Monitor weather forecasts and be prepared to cover frost-sensitive or favored plants that you aren't too sure about. At sunset, drape old sheets, blankets, burlap, or frost cloth over plants. (Don't use plastic because it can increase frost damage.) Allow drapes to hang down to the ground, so that heat radiating from the earth rises up and around the plant, rather than escaping into the atmosphere. Don't tie the material to the trunk, which would eliminate the heat trap.

Take the drape off the following morning before temperatures reach about 50 degrees. If it gets too warm beneath the drape, it creates a mini greenhouse, encouraging plants to break dormancy. Tender new growth is especially vulnerable to frost damage. Some frost cloth can be left on for longer periods; read the manufacturer's specifications.

I hope all of your favorite plants survive the winter!

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