This weekend, even the most thick-blooded Georgians is bundle up in winter coats, hats and gloves. A cold front is moving across the state, and it is predicted to drop temperatures to freezing along our coast by Sunday.

The cooler temperatures may be welcome by some, but for plant people, this is your final warning to get out and either bring in or cover your cold-sensitive crops.

The terms "frost" and "freeze" are often used interchangeably, but they refer to two different events. Freeze is normally used to describe an invasion of a large, very cold air mass from Arctic or Canadian regions. This event is also called an advective or wind-borne freeze. Wind speeds during an advective freeze are usually greater than 5 mph. Clouds are commonly present during much or all of the event, and air is usually quite dry (low dew points).

A radiational freeze (also called a radiational frost) typically occurs when winds are calm, 0-3 mph, and skies are clear. Under such conditions, an inversion may form because of rapid radiational cooling at the surface. If a strong inversion forms, temperatures aloft (usually 100-200 feet up) may increase 10 degrees or more above surface temperatures.

Most people think of frosts as frozen moisture on plant surfaces. However, there are two types of frosts: a white frost and a black frost (also known as hoar frost). If the air temperature is below the freezing point of water (32°F) when water vapor is lost from the air, ice crystals, rather than dew, form and the frost is called white frost. When the dew-point temperature is below the freezing temperature of the air, neither frost nor dew forms. Such a condition is referred to as a black frost.

Damaging frosts seldom occur in Georgia through slow, seasonal lowering of air temperatures. The most common freeze scenario is for a blast of Arctic or Canadian air to move rapidly southward across the state. The first night or two usually features strong winds, clouds and rain followed by clearing skies and the continued importation of very cold, dry air. Thus, advective or wind-borne freezes are common the first one or two nights. With continued clearing skies, the next night or two usually feature radiational freezes (or frosts) and the coldest temperatures.

If you haven’t already done so, now is the time to bring out your winter cloth and have it ready to shroud your plants during when below freezing temperatures are expected. Although satsumas, kumquats, and even Meyer lemons are among some of the more cold hardy citrus varieties, it is best to cover all citrus when the temperature will reach below approximately 30 degrees.

This is especially true if you still have fruit hanging, as 28 F is the temperature at which the fruit will freeze. Place the winter cloth over your trees and set some large pans of water underneath the cloth; the water will release heat during the night, which will raise the temperature under the cloth by a few degrees.

If you have newly planted or young citrus trees, consider cutting some of your freeze cloth into strips and wrap it along the tree’s graft union. If your tree is located near a power source you can also place a light bulb inside the cover cloth for added warmth.

My father-in-law has successfully protected his lemons using Christmas lights!

You can also use the freeze cloth in the vegetable garden. The pans of water are not necessary in the garden since the earth releases heat during the night.

Speaking from first-hand experience, it is much easier to cover the plants the day before the freeze is scheduled. Trust me, it is much easier to cover up your plants when the wind is not blowing your freeze cloth all over the place. Don’t wait until the last minute, get them covered while it is nice and sunny out. Don’t forget that the cover cloth should be removed when the freeze threat has passed. Also, trees in containers that have been moved into a garage for protection should be moved back out into the sun.

Lastly, I wanted to invite you to join me next Saturday for a workshop I will be teaching about growing citrus. The workshop, "Backyard Citrus," will be at the UGA Liberty County Extension office in the Historic Courthouse, 100 Main St., Hinesville, on Dec. 16 from 10 a.m. to noon.

The workshop is geared toward the homeowner but anyone interested in growing citrus, whether you have trees planted or not, is welcome and could benefit. I will discuss basic production methods, the different types of citrus, pruning, and pest and disease management. We will also have a citrus taste test. The cost is $10. To attend, you must pre-register. Come by the Extension office Monday-Friday to register. More details can be found on the flyer and registration form. Please call at 912-876-2133 or email at uge3179@uga.edu to learn more about the workshop.

That’s all for now, cover up those plants and sign up for next week’s citrus workshop.