A late frost, to gardeners, is one that occurs in the middle of springtime and threatens flowers and other plants in a serious manner. These late frosts typically occur when cold fronts move in and the skies are clear at night, making radiation cooling possible as the warmth of the day leaves the air. To combat the killing effects of a late frost, there are some measures you can take, with some more drastic than others.
Avoid planting your vegetable and flower gardens too early. By closely following the tables and charts for your area of when the last frost of the season typically occurs, you can avoid having to deal with a late frost to begin with. Check these tables, which are online as well as in such publications as The Farmer's Almanac.
Pay close attention to the weather. On chilly days in the spring, after you have planted flowers and they have begun to emerge, listen for frost advisories. The television weather, radio and online weather sites will alert you to the potential for a late frost and allow you to go into protective mode to save your flowers.
Cover your plants if there is a frost advisory. Cover plants up before it gets dark since once twilight arrives most of the heat that you would trap under your covering will have dissipated into the atmosphere, making covering the plant fruitless.
Drive a stake or series of stakes into the ground to use as a support frame for your covering. A stake can allow you to swathe plants with newspapers, plastic tarpaulins, sheets, pillowcases or even cardboard.
If you lack the time to employ stakes then lay newspaper right on top of the plants. Utilize flowerpots, milk jugs, coffee cans, paper cups and jars to cover up your smallest plants. Put them right over the plant carefully to avoid injuring them.
Bring out an electric fan to combat a severe late frost. By keeping the air moving, you will not allow the coldest air to settle in around your plants. Use an extension cord but be certain to keep the fan as well as the cord dry to avoid serious injury. Refrain from plugging in a fan aimed at your plants if you cannot guarantee keeping it dry.
Water your flowers and the ground around them before the sun goes down. This action can help save your flowers because the ground will slowly let the moisture go during the night, which has a tendency to keep the surrounding air a little warmer.