Whether it is a late fall chill or early spring freeze, a little frost can be deadly to many plants. Tender seedlings, newly planted flowers, shrubs and trees and even established plants in areas that are not used to cold are at risk when the temperatures dip. Fortunately, there are easy steps you can take when a cold front approaches to be sure your plants stay toasty warm.
You will worry less about your garden or landscaping in a cold snap if you have chosen cold-tolerant, winter-hardy plant varieties. Be familiar with your climate garden zone, and choose plant cultivars that will do best in your year-round temperature conditions. More delicate plants can be positioned in sunny areas where they will stay warmer, and take care not to rush planting dates in early spring so seeds and seedlings are not at risk. If you've planted appropriately, you may not have to make any severe adjustments to protect your plants from frost.
Before the Temperatures Drop
If your plants are thriving and healthy, they will be better able to survive even severe temperature fluctuations. Take precautions throughout the year to keep your plants disease- and pest-free, and keep up on pruning tasks so your plants are always in the best shape. Water all plants appropriately so they are not drought-stressed when cold approaches, and use mulch at the base of plants, in the garden and in flowerbeds to preserve moisture and minimize weeds. All of these basic, healthy steps will help your plants better survive when frost passes by.
When Frost Threatens
You won't know your plants are at risk if you don't keep a close eye on the weather, paying special attention to cold fronts and approaching storms that may indicate quick temperature drops. When that poor weather is imminent…
Bring containers and hanging baskets inside.
You can easily protect containers and hanging flower or herb baskets from frost if you just bring them into a warmer area. Bring containers into a garage, shed, porch or entryway to protect them from the frost. If the indoor area is not heated, wrapping a blanket around the plants' pots will help preserve the heat already absorbed by the containers. Just being indoors and out of the harshest wind chills will be immensely helpful to protect your plants.
Water well for plant health and soil insulation.
Water plants very well 2-3 days before the frost is predicted, if possible, but avoid watering the stems or foliage where even a small bit of frost or ice can cause severe damage. As the plants uptake extra water, they will be better protected from cold desiccation. Water in the soil acts as a natural insulator and heat absorber as well, keeping the soil temperature higher so delicate roots are better protected.
Add extra mulch for insulation.
Adding more mulch to your plants before a frost arrives can help provide an extra layer of insulation, especially over delicate roots. If plants are very small, such as newly planted seedlings or seeds that have just sprouted, you can cover them completely with mulch to a depth of 4-5 inches, but remove the mulch as soon as possible so the tender plants do not smother.
Cover plants the night the frost is predicted.
Covering plants with an inverted pot, burlap sacks, canvas, sheet or other cover can help protect them from frost by conserving heat that rises from the soil, as well as cutting down on wind chill through the foliage. A dark-colored pot or fabric will absorb any solar radiation that is available to help heat the plant, but be sure the cover does not touch the foliage. The cover should allow some air to circulate so the plant does not stifle, but be sure no breezes can get under the cover strongly. Covers should be removed as soon as the temperature warms up the next morning so plants are not deprived of critical sunlight.
Add heat under plant covers in case of severe cold.
Small, safe heat sources can be positioned underneath plant covers if severe cold is predicted. A strand of small, non-LED holiday lights can be wrapped around the plant to help provide warmth, or an outdoor-rated heating lamp cold be positioned under a large cover. Be sure all lights and cords are safe for outdoor use, and monitor them closely so there are no safety concerns. For a non-electrical alternative, fill plastic jugs with water and set them indoors or in bright sunlight, then move them under the plant covers as the temperatures fall. The jugs will gradually release their absorbed heat to protect plants.
While you can take a lot of steps to protect your plants from frost, some damage is inevitable if the temperature dips low enough. When that happens, prune or groom your plants appropriately to removed dead, damaged sections, and you'll be surprised at how well the roots may regrow and most plants can recover.