Late Spring Freeze: How to Protect Your Summer Plants (for the backyard grower)
Variable Weather Patterns
The western NC mountains are known for their variable weather patterns. Warm spells in January and cool spells in the summer are not uncommon.
Many backyard growers and gardeners get very excited by 70—and 80-degree days in April and start planting our warm-season plants. Yet often, our region gets hit by a frost in the late Spring, sometimes even in early or mid-May.
Mother’s Day Last Frost
Mother’s Day is generally considered the last frost date in much of Western NC, although that can vary due to the myriad of microclimates in and around the hollers.
Tips for Protection
But don't worry! Here are some tips that can help you save your already-in-the-ground summer plants, such as tomatoes, summer squash, cucumbers, peppers, and more. Without some protection, those plants will not survive the frost.
Water your garden thoroughly before the freeze. Make sure both the soil and the plant itself get watered for protection of the roots and upper portions. If you have a sprinkler, use that. Make sure everything gets sprayed. While it may sound counterintuitive, the water acts as an insulator of sorts. The water freezes and therefore protects the plant matter from freezing. This is a tried and true tip in the orchard industry, where fragile flowers can easily be frozen, losing the entire crop of fruit. Running sprinklers before and during a freeze protects the flowers and the buds.
Cover your plants with a bucket. This will harbor your plants from the worst of the frost by trapping the heat (the ground and soil are warmer than the air) and protecting them from the coldest of the air. Make sure to take the bucket away when the day warms up.
Cover with lightweight fleece blankets. Covering plants with sheets or blankets risks crushing them, but with some care, they can be used effectively, much in the same way as buckets. It traps the heat and protects them from the frost. If you use a sheet or blanket, synthetic blends are lighter weight than cotton blends and will be less likely to break the plant. Put some wooden stakes or stones around the plant to prop up the blanket for extra care. Remember to remove all coverings once it’s warmer, generally the next day when the sun comes out.
If you have a fancy cold frame or hoop house, or if you have many plants, cover them with one.
Bring in your trays of plant starts. Either move them into the garage, into the house, or to a greenhouse.
Cover with mulch or straw anything that’s hardy enough and established enough that you might be worried about. For very low temperatures, figs, for example, might need something extra for support.
Cluster container plants together nearest the house and cover them with plastic or blankets, taking care not to crush them.
Resuming Growth
Cold weather slows summer plants down, but it won’t kill them as long as you provide the proper protection on those few occasions where the temperature edges close to freezing (32 degrees).
Some people do like to wait until all fear of frost is gone before planting, and that’s a fine strategy.
Most people actually like to get summer plants in the ground early to get a jump on the growing and take advantage of those warm spring days. Regardless, always be ready for the extra labor required if a spring freeze hits.
Good luck!
This blog post, written by Lee Warren, was originally published as part of a previous Organic Growers School article series, which addressed the gardening concerns of home growers. Some updates may have been made by OGS staff to keep the content current and consistent.