Freeze protection for the garden and orchard

By By Steve Strong / Extension Service agent
March 6, 2002
The last freeze date for counties along Interstate 20/59 is around the last week in March, so there are still several weeks of cold weather to come. According to the groundhog's shadow, the South is due for an early spring but count on Mother Nature for at least one more hard frost before Easter.
Still, some vegetable gardeners are determined to have the first ripe tomato on the block, and are now realizing where the term "diehard" originated. Planting dates for most warm season veggies begin in mid-April in our region. For folks with plants already in the ground, freeze protection is one of the few options.
Mulch is one of the easiest and cheapest ways to protect plants from harsh weather, and it may consist of just a few inches of pine straw or bark. Entire plants can be temporarily buried underneath the mulch for several days if necessary; just remember where they are planted when it comes time to uncover them.
Other strategies include using some type of row cover such as freeze cloth (also known as Remay). Row covers are convenient for protecting large numbers of plants, but it's important to use a fabric that allows air to flow through it. Plastic sheeting can easily trap too much heat, so it is critical to remove that type of cover on sunny days to prevent plant meltdown.
Some type of framing like wooden stakes or PVC pipe can be constructed to support a row cover, and keep it from touching the plants. High wind can cause freeze cloth to whip against leaves and buds, and plastic sheets are bad about trapping unwanted moisture against leaf surfaces.
Home fruit growers often resort to using plain old bed sheets to cover larger trees and shrubs, and this method works fine. Light-colored fabrics are better at reflecting sunlight and preventing heat buildup underneath the cover. The same goes for plastic use white rather than clear or black-tinted.
The most critical time for frost protection on home fruit is during the bloom period, when any temperature below freezing can kill the buds. That is one more reason to choose varieties that either bloom extremely early or very late to avoid frost injury on the flowers.
Many varieties seem to be able to withstand temperatures down into the mid-20s, as long as the buds are still dormant. One helpful strategy for prolonging dormancy is to wait as late as possible in the spring to prune the trees, because pruning stimulates new growth and causes plants to come out of dormancy earlier.
In fact, commercial orchards may delay pruning until well into March to keep the trees dormant longer. For home growers with fig trees, the general timing for pruning is whenever the buds begin to break dormancy and show some green color (about the first week or two in March).
This is about the same time to begin a fertilizer program on pecans and other orchard fruit. Fertilizer, particularly nitrogen, also stimulates plants to break dormancy sooner, and that is why growers should wait until the start of the growing season to feed the trees.
Contact the county Extension office for more information about vegetable and fruit production, and additional ways to prevent frost injury. Planting at the right time, choosing the right plant varieties and delaying pruning or fertilizing are some of the best approaches but there is always the desperate measure of running a power cord and light bulb out to the garden.