» Gardeners, beware of freeze.
Be prepared for freezing temperatures in the garden
With our recent spring-like weather, many Houstonians have been working in the garden. Now there’s a hard freeze in our forecast.
Best thing to do? Be prepared. Warm days followed by a really cold spell could damage plants. Since they’ve already started their growing season, they are more vulnerable to the cold. And with our mild winter, some tender plants, such as impatiens, are still blooming. But they won’t like what’s coming.
How bad will it be? “Look at the hourly predictions, not just the predicted low,” said Angela Chandler, an instructor for Urban Harvest. “We often experience the maximum low for a very short ‘dip’ that occurs just before dawn. If the dips are short, little damage may occur because there is no holding time in the tissues at or below 32 degrees.”
To prepare for a freeze, mulch beds heavily with bark mulch, pine needles or leaves. Then, water well. This will help protect roots and encourage regrowth, and it may be adequate protection for shrubs that can with
stand freezing temperatures — including roses, azaleas, abelias, boxwoods, hawthorns, holly, ligustrum, loropetalum, nandina, wax myrtle and yaupon.
Temperatures in the low 20s, and possibly into the teens, are forecast early next week. Azaleas and camellias are already budding, and the blooms could die at these temperatures, so they will need cover.
“Frost cloth is best because it is specifically designed to do this job, but you can also use sheets and blankets,” Chandler said.
Look for protective row covers, or frost cloth, at garden centers. If you use blankets, you may need supports so you don’t crush the plants.
A sheet of plastic over the fabric will hold the heat, but don’t let the plastic touch the plants or it will burn the foliage. Weigh the covers down with bricks or stones. Putting a bucket of water under the cover can help keep plants warm, according Texas A&M Agrilife Extension experts.
Remove the covers as temperatures rise during the day so the sun can warm the soil. Then reapply the covers at night if freezing weather is still in the forecast.
It’s a good idea to cover bedding plants also. If temperatures drop into the low 20s, even snapdragon blooms may show damage. Alyssum, calendula, cyclamen, dianthus, pansies, petunias, stock and primrose blooms should be able to tolerate short drops into the 20s without cover.
Some plants — such as duranta, angel’s trumpet and hibiscus — may lose their leaves and tops in a hard freeze. These should return from the roots in spring if adequately mulched. Loquats and oleander can be damaged by the cold, too; keep the roots well-watered, but not saturated.
If your hibiscus or plumeria is in a container, move it indoors or to the garage. You may want to move all your containers into the garage. Because potted plants’ roots lack the insulation of the earth, they can get much colder than in-ground plants.
If you have a sprinkler system, turn it off and drain it, then cover it with a towel or blanket.
After the freeze, don’t remove the frost or ice. Let plants warm up on their own. Raising the temperature too quickly could hurt the plant’s cell tissues. Go ahead and remove soggy plant material from impatiens and begonias, but leave shrubs and woody plants alone. Leaving dead limbs and foliage at the tops of plants will help protect the lower leaves and branches. Delay pruning the damaged wood until the threat of frost is over.
And hold off on your Valentine’s Day rose pruning until this freeze danger is past.