Protecting Crops Against Cold
In temperate climates, the earliest crops have to be grown in a heated greenhouse, but many vegetables can be accelerated by at least a month by using cloches, teepees or row covers -- simple synthetic or glass covers -- outside, with no heating.
To raise an early crop, use these covers for tender vegetables like zucchini, beans, and tomatoes. Since you will harvest these well before outside-sown crops are ready, you will be eating them while store prices are still high. At the end of the season, use your covers again to grow late vegetables when those outside are normally finished. You will find that these season-extenders will pay for themselves in the first year.
Types of crop protection
For individual plants or multiple-sown seedlings, cap-like cloches or water-filled teepees are appropriate. To cover larger crops, protective tunnels or floating row covers can be used. Despite their name, floating covers do not really float. However, these thin sheets of synthetic fabrics are so lightweight that they appear to "float" when draped over plants. Metal support hoops or frames can also be used with these fabrics if desired.
Using plant covers
Coverings are most useful for early planting out of multiple-sown seedlings or early sowings. On heavy soil, incorporate compost or peat into the top few inches to aerate and warm the soil and, later, retain moisture. Position the cloche a month before sowing and planting. Measure the soil temperature - which should be 45°F -- before sowing and planting any of your plants.
The soil under the cloche will dry out faster than the open ground. If possible, install a length of seep hose along the length of cloche, and fit the end to the garden hose. Coverings can also exclude any pollinating insects. So, for a crop like peas that is pollinated by insects, open the cloche during the flowering period, at least during the day.
Start by raising plants on the windowsill, in a greenhouse or under lights: sow in late winter, and plant out under the cloches in early spring. In warm climates, sow directly into the soil in late winter, depending on the soil temperature.
You will only need small amounts of very early pickings, so if you have room for a full-length tunnel, several different vegetables can be grown in the same row.
Organic methods of increasing fertility are even more important for growing out-of-season crops. Every time you change crops, dig the soil and work in as much compost or manure as you can spare.
Making A Tunnel Cloche
The technique described here can be adapted to make a cloche of any size; the measurements will give you a cloche 18 in wide.
- Fix bolts 6in from one end of a 54in long piece of wood, 12 in from the other. Cut pieces of strong wire the same length as the wood. Wind wires around bolts to leave loops and 6in at each end. Peg two parallel planting lines 18in apart. Bend wire into hoops; push into soil every 2 ft.
- Remove lines and cover hoops with polyethylene. Dig a small hole and bury one end under the soil. Pull the plastic tight over all the hoops and bury the other end. Tie nylon twine through one of the wire loops; pull tightly over the cloche and secure to the opposite loop. Repeat with the other loops. Slide the polyethylene up to water.