Square-foot gardening

The key to square-foot gardening is productive, healthy soil. Mel Bartholomew recommends a mix of compost, coarse vermiculite and peat moss-at least enough to equal 25 per cent of the volume of the garden soil. Going whole hog, he suggests building a four-foot-square raised garden six inches (15 centimetres) deep and filling it with an equal mixture of peat moss, vermiculite and compost. Every time you replant a square, remove a trowelful of soil and replace it with the same amount of compost.

That kind of soil management may help guard against a potential problem with square-foot gardening: insect or disease proliferation. “Because you're growing in a confined space, you're cutting down on air circulation between plants. If you ran into a disease or insect problem, it could work against you,” says Toronto horticulturist Judith Adam. But a square-foot garden is intended to make it easier to keep such problems in check. As well, the method requires crop rotation among different squares from one growing season to the next. “Chances are,” she adds, “you have to do so much soil amendment work every year to make it sustainable that you're not likely to get a buildup of fungus spores or insect eggs in soil simply because you're changing or renovating it so often.”

Want to create your own square-foot garden? Mel Bartholomew offers a few tips:

• Start your garden in an area that receives full sun at least six hours a day;

• Build the garden in a bed raised six inches (15 centimetres) and edge with lumber;

• Divide the space into 16 square-foot blocks, then fill with a mixture of equal parts compost, peat moss and coarse vermiculite;

• Plant only one variety of crop per block. Depending on the plant's mature size, plan for one, four, nine or 16 equally spaced plants per square foot;

• Only plant one or two seeds in each spot, and do so by making a shallow hole with your finger. Cover, but do not pack the soil.

• Water each square as required;

• Harvest continually. Once a crop in a square is finished, remove a trowelful of soil and replace it with the same amount of new compost, then plant something different.