Cover any plant you have questions about. When in doubt, cover throughout!

We had more hours of freezing temperatures on Dec. 4 than we had all last winter. But the worst is yet to come. This week, temperatures are expected to drop below 24 degrees — and remain there for at least three consecutive nights — putting your plants and pipes at risk.

Subtropical and tropical plants are especially sensitive. Move the following container plants inside: plumeria, bougainvillea, mandevilla, schefflera, philodendron and other tropicals. Also, lime, lemon, grapefruit and orange trees are less cold tolerant than satsuma and Changsha tangerine. Treat Sago palms just like citrus.

For strawberries and other low growing plants with fruit, protect them with any type of row cover to keep the fruit and blooms from freezing. Pansies, stocks, cyclamen and snaps will lose their blooms if not covered, but they will survive. Lantanas, esperanza, poinciana, firebush, and perennials will freeze to the ground, but recover next spring. Cover any plant you have questions about. When in doubt, cover throughout!

You may not be able to protect a large plant completely so focus on protecting plants from the base above and to the graft. At 20 degrees to 22 degrees, a heat source is necessary. Fashion a tent around the whole tree or base and heat it with Christmas tree lights or a mechanic's light. Turn the light on in the afternoon and leave it on until mid-morning the next day.

You don't need to be overly fussy about the covering. Agricultural fabric, sheets and blankets work well and the seal does not have to be tight. This may be the one time to use plastic to make a tent, as it retains heat well. Just be aware any leaves that touch the plastic will likely burn. Of course, the survival of the plant or tree is most important. Also, use caution when using a heat source with plastic covering. A hot bulb will melt plastic.

Calvin R. Finch is the project director of regional initiatives and special projects for San Antonio Water System.