The sides in your home garden

The beds are now too high to stand on their own, and making sloping sides that will not fall down will greatly reduce the surface area. Some gardeners make rounded mounds and use the whole area.

Better to board up the beds so the sides are sheer and stable, with the whole surface area to grow in.

There's a great debate over which kind of boards are best. We think free boards are best -- recycled container pallets will do, or thicker boards if you can get them. Don't use pressure-treated lumber! It's got arsenic in it and other toxins, and no matter what they might tell you, it will leach out and get into your plants, and quite possibly into you too. There's another debate on how to weatherproof them. Don't use creosote! -- it's a plant poison. Paint or spray them with vegetable oil, or, better, linseed oil. Some linseed oil has toxic preservatives added -- check the label (or use food-grade flaxseed oil, it's the same thing). Or try this 100-year-old recipe for "Everlasting Fence Posts":

"Take boiled linseed oil and stir in it pulverized charcoal to the consistency of paint. Put a coat of this over the timber, and there is not a man that will live to see it rotten." (From "Lee's Priceless Recipes" 1895)

The sides should be about 12-15" high, but use your judgment. When you've built them, spread a third layer of compost on top and hoe it in lightly to condition the path soil. The soil will settle a bit in time, but it should still leave your plants with an easy root depth of about two feet of highly fertile soil to wiggle their toes in. This will support the kind of cropping intensity and crop quality you require from a square foot garden.

Put more boards on the paths, or flagstones, or gravel. Or fill them with dead leaves or mulch (top up as it sinks). All these will help protect the soil from compaction as you walk on it, while mulching will steadily enrich it -- useful space for deep-rooting vegetables.

Gardening