Double digging is a
gardening
Gardening is the practice of growing and cultivating plants as part of horticulture. In gardens, ornamental plants are often grown for their flowers, foliage, or overall appearance; useful plants, such as root vegetables, leaf vegetables, fr ...
technique used to increase
soil
Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former ...
drainage and aeration. It involves the loosening of two layers of
soil
Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former ...
, and the addition of organic matter.
Double digging is typically done when cultivating soil in a new garden, or when deep topsoil is required. On poor or heavy soils, or for vegetable gardens, double digging might be required every 3–5 years. In other cases, double digging is only really needed on starting a new garden, or on total replanting.
First the top layer is dug off with a spade, forming a shallow trench, and then the under-layer (at the bottom of the trench) is dug with a fork. When breaking up the lower layer, organic matter such as
compost
Compost is a mixture of ingredients used as plant fertilizer and to improve soil's physical, chemical and biological properties. It is commonly prepared by decomposing plant, food waste, recycling organic materials and manure. The resulting ...
is usually added to the soil. If the soil is in need of other minerals like
gypsum
Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula . It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, blackboard or sidewalk chalk, and dr ...
or
phosphorus
Phosphorus is a chemical element with the symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly reactive, phosphorus is never found as a free element on Ea ...
, this can also be added here.
A second trench is then started, backfilling the first trench. This process is repeated until the whole bed has been treated. There will be soil left over from the first trench, which is used to fill the last trench.
Walking on top of the bed will tend to compact it, so the gardener must be sure to protect the soil from too much foot traffic.
References
External links
Royal Horticulture Society: Double digging* https://web.archive.org/web/20080415183343/http://www.farm-garden.com/feature/double_digging_gardeners_workout
OrganicGardening.com: Double-Digging How-To
Gardening
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