Nothing sets a gardener's heart aflutter quite like the announcement that a frost is expected. Knowing that a frost can decimate tender vegetable and flowers sets the stage for a flurry of activity to provide frost protection to save the plants. Many resort to blankets and sheets sprawled over the garden, but there are other methods of frost protection you can make from objects around the home.
Homemade cloches provide protection for seedlings in the spring and can be used over small plants any time frost threatens. Cutting the bottom off a gallon milk jug and covering the plants keeps the frost from from reaching the plants. Other options include two-liter soda bottles and overturned buckets and cardboard boxes. Be sure to sink the edges of the cloche into the soil to secure it from blowing in the wind.
Bamboo stakes and old blankets or sheets allow you to cover larger plants when frost threatens. Placing the stakes around the plants and covering them with sheets or blankets creates a physical barrier to frost. Securing the sheets to the stakes with plant ties is recommended to avoid them blowing in the wind. Check that all areas are covered, including the top, to prevent cold air from reaching the plants. The bamboo stakes can also be covered with floating row covers,, plastic or other flexible fabric. Use caution when using plastic, as vegetation that touches the plastic may suffer frost damage. Remember to remove the covers in the morning.
Warming the Area
Lamps, Christmas lights, and bottles filled with warm water may heat the area around your plants enough to avoid frost damage. Two-liter bottles filled with warm water and placed around the plant release heat slowly throughout the night. Erecting stakes, or using an old vegetable cage, and covering the framework with plastic helps to keep the heat near your plants when warm water, lamps, or lights are placed near the plants. If using plastic or fabric with lamps or lights, staple the covering to the cage to prevent it from slipping free and contacting the lights. Again, remove the coverings in the morning.
Warding Off Frost
Thoroughly watering your plants the day before an expected frost may prevent frost damage to your plants. Wet soil absorbs four times the amount of heat from the sun as dry soil. It releases this heat slowly throughout the night, keeping the air temperature above the soil 5 degree Fahrenheit higher than the air above dry soil. According to the Cornell University Extension, these temperatures are maintained until 6 a.m. the following morning. Watering the soil may avoid frost damage when frosts are light, but it is best to combine watering with other types of frost protection.