Care and Cultivation of Permanent Garden Beds

Enlarge Image Image Gallery Use a broadfork in your permanent garden beds to relieve soil compaction while conserving the soil food web. ILLUSTRATION: ELAYNE SEARS

One of the basic tenets of organic gardening is to put as much effort into improving soil fertility as you put into growing your crops. When you use permanent garden beds and pathways, you can concentrate on building soil in deeply worked beds that will improve over a period of years, all the while growing robust, disease-resistant vegetables. Permanent vegetable beds also make more efficient use of water and fertilizer, and soil compaction is limited to pathways where repeated footsteps can naturally inhibit the growth of weeds.

In the 2008 article Gardening for Keeps, I addressed the practical aspects of designing a garden using permanent beds, pathways and green access corridors (which also produce nutrient-rich grass clippings). In this article, I will cover some benefits of permanent garden beds, plus discuss the invisible soil food web and how you can conserve and enrich the life-forms that create superior soil fertility.

Limiting Soil Compaction With Dedicated Beds

One of the big advantages of working in permanent garden beds is that you can limit some forms of soil compaction. Wet soil is especially prone to compaction because water acts as a lubricant. The first time you step on wet soil, it can become 75 percent compacted. After the fourth step in the same spot, 90 percent of the pore spaces are gone. Soil compaction restricts root growth physically because overly dense soil is often impenetrable, plus it handicaps any roots already present by depriving them of oxygen and access to soilborne nitrogen.

You should always try to avoid stepping on your garden beds, but some operations — such as building trellises or using a broadfork — require standing space. In these cases, you can prevent unnecessary soil compaction by standing on a wide board to distribute your weight. Standing on a board or using boards as walking bridges over garden beds will reduce your body’s ground pressure from about 8 pounds per square inch to less than 1. Just as snowshoes make it possible to walk on snow by distributing your weight, boards, wide steppingstones or flakes of baled hay can help protect permanent vegetable beds from the compaction caused by footsteps.

Surface compaction caused by driving rain also can be troublesome, especially for clay soils. When bare soil is subjected to heavy rain, the larger particles and organic matter often wash away in the mud, leaving behind a surface layer of fine particles that dries into a crust. Organic mulches will cushion the soil from the pressure of heavy rain and protect it from erosion. In situations where you can’t mulch — in a newly seeded bed, for example — use a sheet of burlap or other porous cloth to prevent surface compaction. Row cover tunnels cause raindrops to shatter and disperse before they reach the soil, so such covers prevent surface compaction, too.