Nearly any gardener will tell you that frost is likely to occur on the full moon. According to Cornell University, this bit of garden lore has no basis in fact. Many factors determine the likelihood of frost. Cloud cover with light winds protects plants from frost--even when temperatures drop--as clouds radiate heat back to the earth and gentle winds prevents cold air from settling near the ground. The amount of moisture in the soil also affects frost, as moist soil holds more heat and releases it gradually increasing the air temperature above the soil by as much as 5 degrees F.
Prepare for expected frost several days before frost arrives. Water plants thoroughly moistening the soil to the root level. Water early in the day to prevent wet foliage and to allow moist soil to gather heat from the sun. Keep soil moist.
Apply mulch over moist soil to conserve moisture and heat. Black plastic or wood chips hold moisture and heat in, allowing heat to release slowly during the night.
Cover plants with protective fabric on the night of expected frost to further reduce heat loss. Use old sheets to cover the plant completely so the edges of the fabric touch the soil. This traps heat loss and increases air temperature around the plant.
Sprinkle the surface of the plant with water during a freeze. According to Mississippi State University Extension, water protects plants with the latent heat produced when the water transforms into ice, keeping the plants beneath the ice at 32 degrees. Apply water lightly and evenly over plants until temperatures thaw.