Raised beds and double-digging

I recently discovered what double digging really means, and wanted to share, so here is some information for you:

This is the best way of preparing square foot beds. It's hard work, but these beds are small, and if your soil is quite good it won't break your back. If the soil is bad, this is how to fix it once and for all. You only need to do it once, never again.

You need a digging spade and probably a digging fork (or spading fork). D-handled tools are best for this. If the cutting edge of the spade is blunt and burred, sharpen it.

Mark off where you want the beds. Leave space for 15-18-inch-wide paths. Cover the path area with boards so you don't compact the soil by trampling it too much.

Cover the whole surface of the bed with a layer of compost (up to 3" thick), and sprinkle some ground limestone over it (or garden lime if you can't get ground limestone) -- a thin sprinkling, like icing sugar on a sponge cake.

Start by digging a trench across one end of the bed a spade deep and a spade wide. Take thin slices (try half an inch), mixing in the compost as you go. Thin slices are much easier on your back and mix the soil better.

Put the soil in a bucket or a wheelbarrow and dump it at the far end of the bed. Cover the bottom of the trench with another 3" layer of compost sprinkled with lime. If the soil in the bottom of the trench is fairly soft, use the spade to loosen it, again a spade deep, mixing in the compost as much as possible. If it's too hard for a spade, use the fork instead.

Now dig a second trench alongside the first one (thin slices!), moving the soil into the first trench, mixing it well. Compost the bottom of the second trench, dig it or fork it, then dig a third trench, and so on right down the length of the bed. You're left with an open trench at the end, which you fill with the soil from the first trench.

Now you've loosened and conditioned the soil to a depth of about 16" and added about 6" of compost, and loosening the soil will have added some height, so the surface of the bed will be at least 6" higher than the path.