Put on the sprinkler. This one seems contradictory, but it works. Just ask theFlorida’s orange producers and annual/perennial growers. When frost is predicted, let the sprinkler play over your tender plants all night. Why? Water gives off heat as it condenses to ice and will keep the plants warmer than the air.
Water and weed. Moist beds helps heat rise from the soil on chilly nights and warm the plants. Bare moist soils radiates more heat than soil blanketed with mulch or groundcover.
Drape a show curtain, a tarp, a painter drop cloth or newspapers over the plants before nightfall to trap soil heat. For smaller plants cover with cardboard boxes or cover with a fancy-dancy glass cloche. Good method for light frosts. Remove covers in the morning.
Floating row covers. Lay lightweight fleece right over your vegetable sprouts. The leaves may be slightly damaged when the fleece freezes, but the plants are protected right down to -2C (28F). Remove covers in the morning.
String Christmas lights on frost-vulnerable trees and shrubs — the big ones, not the little twinkle lights – the heat from the bulbs can save foliage and twigs from severe damage.
Good luck gardeners. Let us quit our bitchin’ and get crackin’.
More articles and frost-busting methods!
Colorado Master Gardener garden notes: Frost Protection and Extending the Growing Season
University of California’s Frost Protection for Citrus and other Subtropicals
Redwood Barn Nursery: Frost Protection in the Garden