If you haven't yet covered your plants, this morning is the time to do it. The coldest weather yet is headed our way - and the danger to plants come from the length of time we're expecting the hard freeze to last. Just 3 hours at 28 degrees can damage plants - and we're expecting weather in the teens to low 20s for 3 days.
The most important thing to remember about covering plants is to use a breathable material - NOT plastic or vinyl. The damage comes when cold temperatures freeze the moisture in the plant's leaves and buds. A covering like an old bed sheet or a burlap bag will let the moisture evaporate while keeping freezing air from making direct contact with the moisture in the plant. When windy conditions are predicted, as they are for Southeast Texas this week, anchor the sheets down with bricks, rocks or other anchors. Try to keep the fabric off new growth; support it with sticks or plants stakes. We use the metal shepherd's hooks we keep for hanging lanterns and bird feeders.
If plastic is all you have available, use it, but take it off first thing in the morning when the sun comes out. For smaller plants, covering them with clay pots work well. Commercial blankets also are available, like the one pictured here from Megagrow.
The second thing to do is add extra mulch, especially around the trunk of small trees and shrubs. Don't be stingy; pile it up.