How to Predict Frost (and save your vegetation).
If it has been a glorious day, with a clear sky and low humidity, chances are that temperatures will drop enough at night to cause frost. If temperatures are below 32 degrees F, protect your plants!
Frost protection is especially important for tender plants such as geraniums, begonias, impatiens, peppers, and tomatoes.
Cover other plants with frost cloths or other insulators including newspapers, straw, old sheets and bedspreads, or evergreen branches. Avoid plastic covers and use cloth sheets. Cover the whole plant; you’re trying to retain radiated heat.
It’s best to have all covers in place well before sunset. Drape loosely to allow for air circulation. Before you cover the plants in late afternoon or early evening, water plants lightly.
The plants should be mulched, but pull the mulch back from the root of the plants.
Remove the covers by midmorning.
In the fall, the first frost is often followed by a prolonged period of frost-free weather. If you cover tender flowers and vegetables on frosty nights, and you may be able to enjoy extra weeks of gardening.
In late fall, spread a heavy layer of newspaper (topped off by fall leaves) over a portion of a carrot, parsnip, beet, or rutabaga row to allow these root crops to overwinter in the soil without freezing.
Information gathered from The Old Farmer’s Almanac