Even though the early plants you’ve transplanted from the cold frame to the garden are fairly hardy, they’re still susceptible to frost. By adapting the principle of the cold frame, however, you can offer protection to these plants either individually or in row. You might want to try some of these ideas just to give your plants a good start and not just when the frost threatens. You’ll want to use these techniques again in the fall, when frosts threaten the crops you’ve nurtured all summer long.
| Cloches and hot caps |
Cloches and hot caps are individual minigreenhouses that you can buy or make yourself. They are used overnight in the spring and fall to protect vegetables seedlings and tender perennials from sudden frosts. The purchased ones are made of translucent waxed paper, fibreglass, or plastic and may be pointed or rounded. Some have a ventilation hole in the top to prevent severe heat buildup. If you prefer, you can make your own from a large plastic jug. Just cut off the bottom, place the jug over the plant, and secure with a small stake driven through the handle. Remove the lid as needed for ventilation. It’s possible to make cloches from glass jugs, but this is more difficult and requires greater care, since you need to use glass-cutting tools.
Other discarded household items can also be pressed into service. Start looking around and you’ll see lots of potential cloches – plastic ice-cream containers, pails, bowls, plastic dishpans, plastic pop bottles, even opaque plastic bags. If you plant to leave them on during a particularly cold day, don’t forget to punch a few holes for ventilation.
Such season extenders work well on tomatoes, eggplants, and peppers when they’re still fairly young. As the plants get larger, you could make portable frames for individual vegetables, covering the sides and top with plastic sheeting. The plastic sheeting itself, however, may not offer enough frost protection, but it can be supplemented with blankets or quilts.
Hot caps are small domes made of opaque, porous, usually waxed paper, which provides better cold protection than clear plastic, but does not allow as much light in. They are useful for protecting tender seedlings from cold winds. Commercial hot caps are available, or you can make your own from newspaper by folding it to create a hat - something you might have done as a child. Anchor hot caps with a rock or other heavy object so they don’t blow away on a windy day.
| Wall o’Water |
This is the brand name of an ingenious solar-heated plant protector that’s frequently used on tomatoes. It’s a ring of open-ended plastic tubes, which stands about 45 cm (18 inches) high. Place it around the plant and fill the tubes with water. The water gives the ring enough support for it to stand up. During the day the water warms up, and during the night the heat is released. Heat retention and protection for the plant can be increased by tilting the tubes inward, leaving only a small opening at the top.
| Plastic tents |
Erect a tent over a bed of tender plants to protect them from harsh winds and conserve heat. Such a structure operates like a cold frame, except on a larger scale. Because planting is often more intensive on raised beds, tents that cover the entire bed are more appropriate than a bunch of small cloches.
The tent cam be made by erecting a ridge pole, across which plastic sheeting is draped. Alternatives are to build a frame of wood or plastic or aluminum pipe over the bed (the frame can have square corners or be arched) or to use a V-shaped pea-vine support. Fitted over the frame or support are 4 mil plastic sheets that have openings at both ends for v
