The French intensive garden, also known as double-dug raised beds, is the most productive, sustainable method of gardening on the planet. While the French get credit, it has been around for a very long time, as the Chinese have been gardening in deeply cultivated raised beds for millenia - with no loss of fertility.
What is meant by "double-dug"? It basically means that you dig down into the soil at two different levels, loosening it and incorporating compost. The first dig is when you loosen and actually remove (or move over) the top spade-depth's worth of soil (about 10 or 12 inches deep). The second dig is when you loosen the soil beneath that level with a digging fork, going down another 10 or 12 inches, and again incorporating compost. (See video demonstration.)
By loosening the soil very deeply (20-24”) and incorporating a lot of compost, the soil gets fluffed up and raised above its surroundings by a foot or more. This fluffy, loose, deep and friable soil now allows plant roots to grow straight down, rather than going down a few inches, hitting a hardpan, and turning sideways where they compete with each other for water and nutrients.
Hardpan is a compacted layer of soil (a bit like concrete!) that is actually created by rototiling or walking on the soil. It's counter-intuitive, but just below the depth of the tines on the rototiller, your weight and the weight of the machine are compacting the soil. It's easier for plant roots to turn sideways than penetrate the hardpan.
I use the French intensive gardening method because it is cheap, sustainable, preserves natural soil ecology, and produces the world's healthiest vegetables.Advantages
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