DOUG’S BLOG – November and Our First Frost


Here we are in the second week of November and we are experiencing a nice warming trend. Yes, we have had some cold nights with temperatures down into the ’30s. And, yes, some of you have experienced a frost. But, most of us in the Richmond area have yet to have our first killing frost. Matter of fact, many of us still have summer annuals such as impatiens, vinca, marigolds, etc. still happy and in bloom. In addition to this warm trend is our rainfall. To date, we are nearly 15 inches above normal. Even if we don’t get any more rain for the rest of 2020 we will still be ahead for rain for the year.

October 20 is the average date of our first frost of the fall season in Central Virginia. We are now well beyond this point. Only Mother Nature knows when we will have our first frost.

Frost is caused by radiational cooling. This occurs on a calm and clear night when heat from the earth radiates upward into a cloudless sky. As a result, there is a cooling of the soil and plant surfaces as well as the layer of air near the ground. If the temperature drops below 32 F, a frost occurs. On a windy night, there is a mixing of the warm upper air with the cool lower air and frost is less likely.

On a warm, sunny fall day our soil will absorb heat. It releases this heat at night and can warm the plants by several degrees – enough to save tender plants on a frosty night. One gardening practice to help protect plants is with water. If our soil is moist it will conduct the absorbed heat from the surface down several inches. Dry soils do not conduct heat well. Another gardening practice to protect our plants is the use of mulch. Mulch will act as an insulator of heat during the day and release this warmth at night.

Do you ever wonder why farmers will use a sprinkler system at night to protect their plants? This practice works because water gives off heat as it freezes.

So, add some mulch around plants now is a good gardening practice. And be sure all plants are watered if frost is in the forecast. In the Piedmont region, which is Central Virginia, we are now in “peak week” when it comes to leaf color. So, trees with leaves give protection to plants below from damaging frost.

Eventually, the cold temperatures will set in for the season. But, until this happens our soil temperatures continue to be warm which is allowing for a great fall planting season as we get ready for the Holiday season. So, don’t stop planting just because of the calendar month. Now is a fantastic planting season.


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