History tells us our coldest weather comes to the mid-south in late January and continues thru early March. Here are some tips to help keep your tender plants safe from the cold.
Desiccation kills – When soil temperatures drop in winter, water absorption by the plant shuts down. With cold ground, brisk winds will dry the stems of many plants, especially those with green stems like gardenias, and cause some stem dieback. If it stays cold and windy long enough, the plant may be killed to the ground. Fortunately, we are entering this cold spell with well hydrated plants from the wet fall we have had. If you had sprayed dormant oil on the foliage and stems in the fall, the plant would be sealed against water loss, thus protecting it further. Another application of dormant oil will help ensure the benefits last through the coldest part of winter.
Temperature kills – This is more of a problem than wind. Every plant has a temperature at which the stems or trunk can be damaged by cold. It varies by plant variety and by the micro environment the plant is in. The soil temperature, sunlight, duration of the cold, wind desiccation, age of the plant; all these factors will affect that magic number at which a plant can be killed. The lower the temperature, the more plants are likely to be damaged. Very low temperature AND drying wind can be the one – two knockout punch for some plants.
Memphis has long been referred to as being too far north for most plants and too far south for everything else. We grow many plants that are at the end of their range either by winter cold or summer heat. The ones we worry about this month……are the ones from south of here.
So what do we do?
You can protect your plants from the wind by covering low plants with leaves or pine needles. Many of your neighbors have already bagged them for you and brought them to the street…go get them. Larger plants can be covered with cotton sheets for wind protection. We’ve all seen plants that are wrapped with plastic like a piece of candy and tied at the top and bottom. If it is 8° outside, it is 8° inside that plastic bag at night and probably 80° or higher on a sunny day when the air temperature is near freezing. If you use plastic, it needs to be open in the back or have a slot in the top to allow heat to escape if the sun comes out. . The plant can be damaged more by the heat than the wind.
Larger plants that need to be covered for temperature protection should be covered with a large tarp so you can cover the plant and as much ground as possible. You’ll get a little heat from the soil and you can add Christmas lights or a utility lamp to add some extra heat, but you still have to monitor the daytime heat under the tarp.
With falling temperatures you can protect plants by icing them down with the sprinkler as the cold moves in, but use caution not to overdo it and break the limbs. Snow helps protect the plants also and right now, it looks like we may get some as the cold weather settles in this week.
Winter damage can occur any time bitter cold weather settles in over the mid-south. All we can do is take steps to mitigate the damage and hope for the best. Beyond that, there’s nothing to do but wait for spring and see how much actual damage is done, and to what. Until then, keep watering throughout the winter, if Mother Nature doesn’t do it for you, whenever the temperature climbs high enough.