Frost usually happens at temperatures below 32 degrees. It forms ice crystals on plants. The ice freezes the plant’s circulatory system, and it soon withers and dies. The larger the cold mass, the harder the freeze.
Cloudy skies remain our best protection against frost. The clouds act as an insulative layer trapping the radiant heat escaping our buildings and soil. No clouds means the heat spirals off into the sky, replaced by the cold.
High humidity protects against frost. Saturated air holds in heat. As water condenses, it releases heat.
Low areas always are the first to frost, as cold air drains like water. Air could be 31 degrees with frost at ground level and 33 degrees a few feet above.
If you’re planting in hilly areas, temperatures will drop 3 to 5 degrees with every 1,000-foot increase in altitude.
This makes a gently, southward-facing slop the best place for a frost-free garden. Buildings and bodies of water also help maintain warmth by absorbing the sun’s rays.
While mulch provides many benefits to plants, it can encourage frost. Mulch prevents heat from escaping the soil and warming the surrounding air.
To prevent frost damage, water your plants before you go to bed and cover them with newsprint, old sheets or agricultural fabric. Plastic sheets do not provide enough insulation. Tarps are too heavy and will damage plants.
Be sure to remove the covers the next morning. Frost most often is accompanied by sunny skies that day. Heat builds up rapidly under covers and will damage plants.
Contact Jim Hillibish at email@example.com.