I enjoy attempting to grow my own fruits and vegetables in my gardens. However, frost and freezing temperatures can be deadly for certain kinds of plants. When the temperature of the air remains at or above freezing (32º Fahrenheit), most plants will only suffer minor or no damage if the night suddenly turns cool. However, if the temperature drops below freezing, the cells of plants that are not frost hardy may freeze, resulting in the death of the plant. As the weather has turned cold in my neck of the woods, I have again begun thinking about how to protect my plants from the cold. Fortunately, learning how to protect plants from frost and freezing temperatures can be quick and easy with these simple tips and instructions.
Frost Hardiness of Plants
Before you should scramble to protect your outdoor plants from freezing temperatures and frost, you should first determine and understand the frost hardiness of each type of plant. Frost hardiness refers to the degrees of different types of frost that a plant can withstand without damage or death to the plant. The four levels of frost hardiness are very hardy plants, hardy plants, half hardy plants, and tender plants. Very hardy plants can be planted up to seven weeks before the last frost, hardy plants up to five weeks before the last front, half hardy plants up to three weeks before the last frost, and tender plants after the last frost. Some of the most popular types of frost hardy plants include the following:
Very Hardy: alyssum, asparagus, carnations, chives, dusty miller, fennel, kale, onions, pansies, peas, potatoes, radishes, snapdragons, strawberries, sweet pea, thyme
Hardy: anemones, baby’s breath, broccoli, Brussels sprouts, cabbage, cauliflower, day lilies, dianthus, English daisies, flax, forget-me-nots, hollyhocks, hostas, lavender, lettuce, mums, painted daisies, poppies, rhubarb, roses, spinach, Swiss chard, violets
Half Hardy: artichokes, celery, cosmos, hibiscus, leeks, peonies, petunias, purple coneflowers, roses
Tender: African daisies, bananas, begonias, black eyes Susans, cannas, cantaloupe, chrysanthemums, cucumbers, dahlias, eggplants, fuchsias, geraniums, heliotropes, impatiens, jasmine, marigolds, morning glories, okra, oleander, peanuts, peppers, periwinkles, pumpkins, sunflowers, squashes, sweet potatoes, tomatoes, watermelons, zinnias
Tips for Frost Protection
The best way to protect plants from frost and freezing temperatures is to plant at the appropriate time. For example, the typical last frost date in central Illinois is May 15, so a gardener living in this area would plant very hardy plants no earlier than March 27, hardy plants no earlier than April 10, half hardy plants no earlier than April 24, and tender plants after May 15. If you do plant too early or a frost happens later than expected, the best course of action is to cover plants to offer protection against freezing temperatures and frost. Things that you can use to cover your plants include newspaper, cardboard, old blankets or sheets, burlap sacks, and plastic tarps. Cover plants at sunset, and remove coverings first thing in the morning to prevent plants from being crushed or suffocated. If you have potted plants, simply bring these inside for the night instead of covering.
Because air temperature drops faster than ground temperature, you can also prevent frost damage to plants by helping the heat from the earth rise or by keeping the cold from the air away from the plants. To use the heat from the ground to your benefit, water your garden thoroughly at sunset. The soil will release moisture throughout the night, which will warm the air around the plants. However, do not spray water directly on plants because remaining water droplets could freeze. Mulch can also be used to trap heat around plants. To collect heat throughout the day and channel heat towards plants during the night, place plastic buckets or contains around plants. Buckets work especially well for tomato and pepper plants and also help to prevent rabbits and other animals from nibbling at seedlings. If you have a small garden or own many electric fans, you can also set up fans to blow cold air away from plants through the night.
Freezing temperatures and frost can be damaging or deadly to certain garden plants that are not considered frost hardy. However, learning how to protect plants from frost is simple with these easy instructions and tips. Even I have been able to manage to protect my outdoor fruits and veggies from the cold!
Frost Hardiness of Plants: http://www.echters.com/FrostHardiness.htm
Frost Hardy – (Gardening): Definition: http://en.mimi.hu/gardening/frost_hardy.html
Frost: How to Protect Your Plants: http://www.gardeningknowhow.com/problems/frost-how-to-protect-your-plants.htm
Frost Protection Methods for Your Plants and Gardens: http://www.thegardenhelper.com/frost.html
Tips for Protecting Outdoor Plants from Frost and Freezing Temperatures: https://www.flickr.com/photos/98176074@N03/15384328913/ (CC BY-NC-SA 2.0) and https://www.flickr.com/photos/lunaspin/2960457357/ (CC BY-NC-SA 2.0)
USDA Plant Hardiness Zone Map: http://www.usna.usda.gov/Hardzone/ushzmap.html