Cold frame how-to
Let plants get acclimated to the sun and wind for a few days, then finish hardening them off in a cold frame. This handy structure is made to protect plants from harsh weather and get them ready for the rest of the season with no added heat source.
- Choose a location Position your cold frame in full sun, near a water source and out of the cold north wind. A spot on the south side of the house or garage provides lots of sunlight and reflected heat. Set a thermometer inside, but out of direct sunlight, so you know the temp.
- What to use This cold frame was made using two-string straw bales, which are good insulators. At about 36 in. long, 18 in. wide and 14 in. tall, six bales form a 6-ft. square with a 3-ft. opening in the center for plants.
- Heat it up Whatever your cold frame is made of, it needs a clear cover, like these two old windows. They hold in the warmth accumulated from sunlight during the day so night temps (or frost) won’t damage plants. During the day, prop open the cover to acclimate plants to the weather and prevent them from overheating. Do this until plants have adjusted to warmth, light and danger of frost has passed, and seedlings will be ready to successfully go into the ground or containers.