Plant with Frost

Facts About Frost

April 6, 2023
Sue Adams

Early Spring Planting

Ah, it’s a beautiful day, and you can’t wait to start planting! New trees and shrubs, most herbaceous perennials, pansy, snapdragon, lettuce, spinach, peas, chard, collards, beets, carrots and radishes can tolerate a frost. Semi-tender plants that will tolerate a light frost include broccoli, cauliflower, petunia, lobelia, geranium, dusty miller, osteospermum (cape daisy), nemesia, verbena potatoes, corn and parsley.

Whoops! I planted and there’s a frost warning!

Cover the plants with a light weight, breathable and insulating fabric – blankets, bed sheets, towels. Or cover with straw, newspapers, leaves or other organic matter. You can also make your own cloche or hot cap by cutting off the bottom of a gallon milk jug and removing the top. You can cover your lettuce with the hot caps, and when the lettuce is ready to harvest, move the hot caps to tomato plants – instant little greenhouses!

Vegetable Garden Advice

Adams Fairacre Farms Easy Vegetable Guide tells you which seeds and plants when.

A Few Facts about Frost

Frost usually forms at night when the air temperature is cooler. Once the sun rises and warms the ground, frost on plants will melt quickly.

Light Frost vs. Hard Frost
Many plants can survive a light frost but few can survive a hard freeze. A light frost occurs when the nighttime temperature drops to at, or just below, 32°F. A hard freeze is a period of at least four consecutive hours of air temperatures that are below 28°F.

Meteorological conditions that can lead to frost conditions:

  • Clear skies
  • Calm to light winds
  • Cool temperatures
  • Local topography (cold air will settle in valleys since it is heavier than warm air)

Frost Advisory vs. Freeze Warning

  • Frost advisory is issued when the minimum temperatures are expected to be between 33°F and 36°F. Skies are generally clear and winds light.
  • Freeze warning is issued when minimum temperatures are expected to be 32°F or less
  • Hard freeze warning is issued when minimum temperatures are expected to be 28°F or less.

Sources: Old Farmers Almanac, National Weather Service