Protecting Plants from Spring Frosts

Tenting in a Clematis on a trellis in the Circle Lawn with an industrial-sized garbage bag during the warmer daytime temperatures to prepare for this evening's cold snap.

After two weeks of unseasonably warm weather in Pennsylvania, we are preparing for the temperature to plummet down to 24 degrees F (-4 C) this evening. Some thoughts on temperature fluctuations in a garden during spring:

1. Do not panic - For the most part, plants that come out of dormancy in the springtime are accustomed to coping with sudden cold temperatures. Most plants in zone 5 and colder are even able to withstand several inches of snow; once it is melted, they will continue their bloom again where they left off before the snow storm.  (I have seen tulips ready to bloom flopped on to the ground, covered in snow, that stood up to bloom when the sun came out again.)

2. Air temperature drops more quickly than soil temperature - Plants that are up in the air away from the ground are going to meet the colder temps more easily. For example, a Clematis on a trellis is not going to benefit from the ambient heat from the soil like a Clematis that is scrambling on the ground.

3. Remember to bring in seedlings, annuals and houseplants that were given a early airing - They will not appreciate the fluctuations.

4. Protect plants with covers which are budding out of their normal season - In our zone 5 garden, we are about a month ahead of a typical growing season. Our roses and lilacs are budding, peonies are a foot-high, and my butterfly bushes are covered in foliage.  I have chosen to try ensure a few of these come through unfrosted by covering them with row cover fabric rated for cold temps (which I also used to cover our herbs and salad for the winter months), and even plastic garbage bags to hold in the warmer temperatures. I think that tenting them during the warm daylight hours will give them the best chance of coming through unscathed. Remember to remove these coverings as soon as possible to discourage disease.

5. Remember that damage in most cases will not be permanent - If the frost in your area should be more dramatic, killing even the leaves on your trees, remember that it will not last. Trees and plants may be set back for the year, especially in the case of budding and blooming fruit trees, but most plants will rebound within months. Gardens are generally resilient.

Use row cover fabric or sheets to tent in plants that are budded far too early for their own good.

Garbage bags tent in our young Persian lilac and a newly pruned lavender in the Driveway Garden.

How has your garden weathered these temperature fluctuations?