Frost is the fastest way to have a garden go from a great start or lush harvest to utter destruction literally overnight. It’s the largest non-pestilence killing crops worldwide. Many farmers and fruit growers are beholden to frost and lose entire crops and seasons to it when it freakishly appears late or early. Luckily, there are ways to avoid frost.
Every year, the first frost (called “last frost”) happens at a known time. This is plotted using moon phases and days from solstice and is predicted in almanacs. Most growers assume that the last frost date in the spring will be inside about a week’s window of the prediction. So if last frost is predicted to be on May 17 in your area, it could actually happen anywhere between May 10 and May 24. Most gardeners plan to begin planting outdoors around May 24 or so in that case. It gives a nice safety zone.
Similarly, the first frost (called the “killing frost”) happens sometime late in the fall. Again, almanacs predict it and most gardeners assume a week window around it. So they’ll try to have all of their harvest in before the week of the killing frost’s date.
Of course, sometimes freak weather happens and an unexpected frost will happen. Astute gardeners will be tracking the weather and know it’s coming and prepare for it. There are several ways to protect young plants from a late frost.
Preventing Frost Damage in the Vegetable Garden
One of the cheapest and oldest ways is to mulch over and around the plants when the weather is going to turn. Sometimes this is done heavily around the roots, potentially sacrificing new growth leaves, but saving the plant. Other times, the plants are literally buried, risking crushing the new plants.
Another option is to use low tunnels to hold the heat in overnight, to cover the plants in a tarp (as a similar precaution), and to use specialized protection apparatus like water towers, etc. Cold frames and similar tools can also be built to beat the frost and extend harvests or begin planting early.
If an early frost is coming, just before things are ripe, many gardeners will just harvest “green” everything that they can ripen (or use) off the plant. Tomatoes can be harvested and used green (and sometimes ripened in a paper sack), for instance, as can some cucumber varieties and most lettuce and related plants.
Many plants are tolerant to light frosts and will even thrive in the cooler weather. These are preferred fall planting or early planting options to extend the growing season without special equipment.
Frost Tolerant Fruits and Vegetables
Here are some cold temperature tolerant plants: beans, cucumbers, eggplants, okra, pepper, pumpkin, squash, sweet corn, sweet potato, and watermelon.
Here are some semi-hardy plants that can tolerate a light frost (just under 36 degrees for a couple of hours): beets, carrots, cauliflower, celery, endive, lettuce, parsnip, potato, and salsify.
Finally, hardy plants that can tolerate a hard frost and are likely picks for fall planting: broccoli, brussels sprouts, cabbage, kale, mustard greens, onion, peas, radish, spinach, and turnips.
Planning ahead and understanding how to plant when cold weather is setting in can mean getting a second harvest out of your garden every year!
Want to learn more about how to avoid frost with vegetable gardens?
Check out these great resources:
Protecting Your Garden from Frost: Critical low Temperatures for Frost Damage to Vegetables from The Old Farmer’s Almanac
Getting Ready for Frost