Protecting plants from cold takes planning
Earlier in the month, we had a cold spell that sent temperatures to only 38 degrees, but considerable damage was still done to plants on some sites.
Porterweed, vincas, zinnias, moss roses, angelonia and other blooming plants had freezelike damage. Some of those plants might be damaged at 38 degrees, but most of the damage was probably caused by the high winds that accompanied the drop in temperatures.
What is clear is that it is time to prepare to protect the cold-sensitive plants in our landscapes from winter weather.
Start by moving tropical and subtropical plants, such as bougainvillea, Chinese hibiscus and mandeville, into a sheltered location where temperatures can be kept above 40 degrees.
Despite the winds, tomatoes in the vegetable garden escaped most cold damage. This means you may have another three to four weeks before the next freeze for the fruit to gain some size and ripen.
The best strategy with tomatoes may be to collect all the large fruit before the cold arrives and let them ripen in the house. If a freeze is light, you may get another reprieve by covering the
plants with a blanket or other fabric. Peppers are in the same league.
Most of the greens can tolerate light freezes, but broccoli and cauliflower get increasingly sensitive as their crops mature. Some gardeners cover them with fabric in a hard freeze. Root crops fare pretty well, with beets, carrots and turnips surviving even if their tops freeze.
To protect lemons, limes and other coldsensitive fruit trees that are planted in the ground or are too large to move to shelter, be prepared with
two layers of cloth that can be used like a tent over the plants.
If temperatures are forecast to drop below 26 degrees, you also should have sources of heat in the cloth covers. Poultry heat lamps work well. If you use mechanic lights, make sure the bulbs are not heat-free LED sources.
Grapefruits, kumquats, calamondin and satsumas are less cold-sensitive than limes and lemons. It is reasonable to cover them when temperatures are 26 degrees or less and to use heat sources at 24
degrees.
Pansies and violas keep blooming through most freezes, and snapdragons, stocks, dianthus, calendula, primula and sweet peas do a fair job of resisting cold spells but can be covered. Cyclamen foliage is cold-hardy, but the precious blooms do best if protected with a layer of fabric when the temperature is going to fall below 28 degrees.
Freezing temperatures will kill the tops of hot weather perennials such as esperanza, poinciana, fire bush, salvias and lantana, but they will
grow back in the spring and bloom in the summer. The choice is to prune off the killed tops early after the freeze or wait until late spring. The advantage to waiting for late spring before pruning is that winter birds use the killed tops for cover, and seek out insects and seeds on the stems.
More information on winter freeze protection is available at plant answers.com.