Unless you have a very large area of land at your disposal, the key to success as a self-sufficient gardener is to be able to grow a lot in a small space. Of the new techniques for growing more vegetables in smaller areas, the most important in my view is what I call the deep-bed method, which is being developed in California by several Americans, several Chinese immigrants to the US, and an Englishman named Alan Chadwick.
The method is derived from age-old techniques that have been practiced in France and China, but which have never been widely adopted in the West. The essence of the method is to dig deeply and then never step on the bed. This means your plants are growing in very loose, deeply dug soil; their roots will go down instead of sideways. You therefore get bigger plants, and can grow them closer together.
A deep bed should produce about four times the yield by weight that a conventional bed will produce. A deep bed of 100 square feet (9 sq m) can produce from 200 to 400 lb (90–180 kg) of vegetables a year. According to the US Department of Agriculture’s statistics, the average American eats 322 lb (145 kg) of vegetables a year. Thus one tiny bed—just pace out 20 feet by 5 feet (6 x 1.5 m) on the floor to get an idea of the size—can keep one adult supplied with vegetables.
From what I have seen of deep-bed gardens in the United States, and from my first hand experience on my own land, I can say that the claims made for this method are by no means exaggerated. I think it highly likely that more and more serious vegetable gardeners will adopt this method. If your aim is to grow as many vegetables as you can in the space available to you, then I urge you to study the technique and try it.
You can create a deep bed by digging to a spade’s depth and loosening the soil to a further spade’s depth. You must incorporate a large amount of manure and never step on the bed. The very loose soil will allow the roots of your crops to penetrate deep down, instead of spreading sideways as they do in conventional beds. You will get bigger vegetables and you will be able to grow them closer together.