JACKSON, Wyo. — With temperatures forecast to dip to 27°F this evening, it’s essential to give gardens, flowers and vegetables a little extra TLC before the sun goes down.
A good rule of greenthumb is that frost-hardy plants and vegetables — think spinach and kale — can survive a cold night down to 28°F, says The Old Farmer’s Almanac. Any colder than that, and there is risk of damage come sunrise, especially to blossoms. Most of Jackson Hole is in plant hardiness zone 4b. The Old Farmer’s Almanac states that this area has a year-round risk of frost, but Wyoming Master Gardener Janetta Teichert has said most gardeners estimate that the risk of a hard frost typically drops off in the last week of June.
The easiest and fastest thing a gardener can do for their plants during a frost is cover them up. Most garden stores and nurseries will sell frost cloth, which is made of nonwoven polyester and can be purchased pre-cut or by the yard from a roll. A light bedsheet makes for an inexpensive substitute that works just as well. For the best air circulation, be sure to drape the fabric loosely over the plants, and try not to let it rest directly on the stems; use stakes or other garden tools to prop it up. The fabric should hang all the way to the ground.
The Old Farmer’s Almanac warns not to use plastic sheets or tarps, as they are not breathable. Though, small plants can benefit from being covered by an upside-down bucket, tented newspaper, or a paper bag — just don’t squish the flora.
“While frost is still possible, plant cool-season crops that are more tolerant of colder temperatures,” says The Old Farmer’s Almanac. “Crops like peas, spinach, kale, and cabbage can power through a light spring frost. Start tender or warm-season crops — like tomatoes and peppers — indoors or after the threat of frost has passed.”
Frost cloth or sheets are best applied in the evening before dark the night before a frost. This allows for good visibility, as well as a period of typically low wind. Weigh the edges of the fabric down with rocks or tools to prevent it from blowing off. The cloth should be removed in the mid-morning, after temperatures rise.
Learn more about the frost-hardiness of various vegetables and how to protect plants from chilly spring temps here.
