Whether you're trying to save young plants from an unexpected late frost or shelter mature plants from an early fall frost, techniques for keeping garden plants from freezing is an important tool that every gardener should know. Here's how to do it.
The tried an true method is covering you garden with a light blanket or tarp. If neither of these are available, newspaper will also work. This technique works well for more mature plants that are not yet ready to be harvested. Blankets can easily be draped over tomato cages or other enclosures. It is important to remember, however, that these coverings must be removed once the sun comes out in the morning. The blanket technique is the fastest method for protecting garden plants from freezing, and can be accomplished quickly if it is late and there is not time for anything else.
Another idea for protecting garden plants from frost is to cover individual plants with empty plastic milk jugs. This method takes some planning, requiring you to save and wash old milk jugs, cutting off the bottoms of the jugs so they can be placed over each plant. This technique is best for young plants that are especially susceptible to freezing. The plastic milk jugs act as mini green houses, trapping warm air to protect garden plants from freezing. The edges of the jugs should be covered with soil or rocks to keep them in place in case of wind.
The last technique to protect garden plants from freezing takes the most preparation and thought, but can help lengthen your garden's growing season allowing for better harvests. "Cold Frame Gardening" is a technique used by many gardeners and works especially well with raised bed gardening. This method takes the mini greenhouse idea to the next level. A "Cold Frame" is essentially an enclosure with a transparent roof, allowing light to enter and trapping heat inside to protect plants from freezing temperatures. You can buy cold frames pre-made or in kits, or you could construct your own using a wood frame and old glass windows or heavy plastic. The benefits of cold frames go beyond just saving your garden plants from freezing, and can extend your growing season by allowing young plants to be transplanted earlier and mature gardens to grow later into the season. This technique cannot only be used to shelter plants from freezing, but can be used full time for winter-hardy plants late into the fall or early winter.
Whichever method you use to protect your garden plants from freezing, make sure the covering is removed as necessary to allow the plants to get enough air and not over-heat. Hopefully, using these techniques will help you save the fruits and vegetables of your labors!