Predicting Frost

Being successful in the garden requires some level of being able to expect the unexpected. While frost isn’t exactly an “unexpected” phenomenon this time of year, recognizing its tell-tale signs can help you save your garden.

Being successful in the garden requires some level of being able to expect the unexpected. While frost isn’t exactly an “unexpected” phenomenon this time of year, recognizing its tell-tale signs can help you save your garden.

Predicting frost will give you some time to decide what plants to protect and which ones to let go. Here are a few tips on what to look for to determine if frost is on the way:

Clouds. Look up for your first hint on an impending frost. If there are no clouds and the temperature is falling, chances are good that frost will land on your garden. If there are clouds in the sky, you don’t have as much to worry about. Clouds act as insulation and keep the frost from reaching the ground.

Breezes. The ground absorbs warmth from the sun all day, and at night the heat rises into the atmosphere and cold air settles around the plants. Gentle wind gusts keeps warm air moving around just above the ground level. Frost is less likely on a night with a soft breeze.

Frost Pocket. Heat rises, proving that cold air is heavier than warm air. The cool air can be so heavy, in fact, that it pools in low places (bottoms of hills, valleys) just like water. This area is known as the “frost pocket.” If your garden is at the bottom of a slope, it’s more likely to experience frost than the top of the same hill.

Dew Point. As the temperature drops overnight, the air holds less moisture, until it finally condenses and forms dew. The temperature at which the water in the air condenses is called  the dew point. When dew forms, heat is released and the heat helps keep the air temperature at or slightly below the dew point. When there is more moisture in the air at sunset, there is less chance that frost will occur in the morning. Turning on your sprinklers can help to increase air moisture and prevent frost as well.