Tilling aerates the soil and loosens it enough so that vegetables can produce a healthy root system. However, deep tilling is only recommended for new garden sites. Established gardens have an ecosystem made up of micro-organisms and other life forms working tirelessly below the surface that help condition the soil. The tilling depth generally is determined by the age of the garden, and it is further influenced by the crops you grow.
The first year you put in a vegetable garden, till the soil to a depth of 6 to 10 inches. The tilling process is done when the soil is slightly moist and not wet. Wet soil will clump as it dries, causing problems with planting and seed germination. Amend the soil with about 2 inches of compost or organic matter to provide better drainage and aeration. By the time the soil is tilled and amended, the soil has a workable depth of 8 to 12 inches.
Double Digging New Gardens
Double digging is done with a shovel instead of a rototiller. The result is a garden bed that has the soil loosened to a depth of about 24 inches. The process divides the garden into rows about 1 foot wide. The soil from the first row is removed to a depth of 12 inches and placed along side the last row. The remaining soil is loosened to a depth of 12 inches. Once the first row is done, the top 12 inches of soil from the next row are turned over into the first row. The remaining soil is worked as it was in the first row. The object is to continue moving the soil from one row to the previous row until you reach the last row. The top soil from the first row is then used to fill the last row after the bottom soil is worked.
If your vegetable garden is established, deep tilling is not necessary. A single-dig method works well for existing garden beds. The topsoil is simply turned over where it lays. This avoids bringing buried weed seeds to the surface or disturbing the existing ecosystem below the surface. For the single-dig method, lift the top 2 or 3 inches of soil with a shovel from the surface and turn the shovel over so the soil falls back into place. This loosens the top layer so you can rake it for an even planting surface for seeds or new plants.
If your garden is on a slope or your health does not permit physical labor, consider using a no-till gardening method. A no-till method keeps the existing soil in place but adds a layer of planting material that composts throughout the year to provide the nutrients for the plants. This method is also known as lasagna gardening. The first layer consists of several layers of newspaper or thick cardboard, followed by a layer of well-rotted manure or heavily composted material. The layers are made up of grass clippings, straw, dead leaves and other organic material. The result is a garden bed that is about 8 to 10 inches deep, made up of organic matter that keeps the moisture in and the weeds out.
Your Planting Articles
- University of Arizona College of Agriculture: Vegetable Garden: Soil Preparation
- University of California Agriculture and Natural Resources: Vegetable Gardening 101
- Payne's Nurseries and Greenhouses: How to Create New Beds by the Double-Digging Method
- BBC: Digging Your Garden
- Oregon State University Extension Service: No-Till Garden Beds Save Water and Labor
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