As we head into Fall, you’re probably looking forward to harvesting the fruits of your labor. But along with the cooler weather, the occasional overnight frost can threaten your garden and your harvest. Freezing temperatures overnight can injure your plants by causing ice crystals to form their cells. Fluids cannot move inside frozen plants, and water is unavailable to them. Tender plants cannot tolerate freezing temperatures and will appear water-soaked, shrivel, and turn dark brown or black.
You can protect your garden from fall frosts in a few different ways, but you can also use forethought to plant your garden in an optimal location to prevent frost damage. Tender species should not be planted in open, exposed areas or in low spots where cold air settles. A better location is near a south or west-facing wall, which absorbs heat during the day and radiates it out at night. Fences, boulders, shrubs, and other insulating items also can serve as protection for plantings.
If your garden is already planted, follow these tips for preventing frost damage:
Bring Potted Plants Indoors
Potted plants are especially prone to frost damage because they won’t benefit from heat radiated through the ground. Once dusk falls on a cool and clear night, bring all potted and hanging plants inside. Your home may be too warm for these plants, so garages, sheds, and basements are all better places to store these plants overnight.
Add More Mulch to Your Garden
Use mulch to form a protective layer around your plants. 3-6” of straw, wood chips, leaf mold, or piles of leaves will effectively insulate the root systems of your plants.
Water in the Afternoon
At the warmest part of the day, in the afternoon, water your plants. The moisture in the soil can insulate the plants and radiate heat upwards during the night.
Cover Your Plants
Just like you need a blanket in the winter, so do your plants! When a frost is coming, cover your plants with a cloche or cloth. A cloche is a bell-shaped plastic or glass cover that fits over small plants. Blankets, bed sheets, tarps, towels, and drop cloths all make for appropriate blankets to cover larger plants and entire beds. Be sure to use stakes and create a tent-like covering that does not touch and damage your foliage.
Be sure to cover your plants at dusk and remove coverings first thing in the morning to prevent damage to your plants.
Wrap Up Young & Citrus Trees
To prevent stunted growth and reduced harvests, wrap young trees and cold-sensitive citrus trees with towels, blankets, cardboard, rags, burlap, or felt. You’ll want to wrap the trunk and the lowest branches, and secure the wrappings. If the weather is expected to stay cold for a longer period of time, add plastic on top of the softer wrappings.
If your plants do succumb to frost and you find them wilted, black, or brown, wait until spring and warm weather before pruning them. Dead branches and twigs provide protection, so holding off until you see new growth can help to encourage it.
Some vegetables are actually purported to taste better after a frost. These include: carrots, potatoes, beets, parsnips, turnips, onions, garlic, radish, rutabaga, broccoli, cauliflower, kale, Brussels sprouts, cabbage, bok choy, collard greens, spinach, lettuce, Swiss chard, arugula, tatsoi, and mache.
Be sure to plant trees and plants that are native to your region and are more adapted to the changes in weather. Monitor the weather frequently, and take proper precautions when a frost is expected.