Successful organic gardening starts with good soil. By tilling and mixing in amendments such as compost, you make the soil crumbly enough for roots to penetrate. Excess water can drain through it, yet the moisture, nutrients, and oxygen that plants need are retained. Enriched soil also supports beneficial bacteria, fungi, and earthworms, which help guarantee plant health.

Bud Stuckey, Sunset's test garden coordinator, achieves this perfect soil by using a combination of soil amendments and cover crops.

If you're just starting your garden this spring, turn the top 8 to 12 inches of the soil using a rotary tiller (available at tool-rental yards). Pick out any rocks larger than a small plum, spread a 3-inch layer of compost over the plot, and till again.

After sprinkling the plot with water, let the soil settle for a couple of days before planting.

Add nutrition each season

IN SPRING AND SUMMER: Compost tea, a rich brew made by steeping a burlap bag of compost in water, adds nutrients to the soil and increases the amount of microbial life the soil contains. That in turn reduces the load of pathogens in the soil and keeps plants healthier.

Apply the tea several times during the growing season. You can buy the materials you need to make compost tea from companies such as EPM (800/779-1709), Growing Solutions (888/600-9558), and SoilSoup (877/711-7687).

IN FALL: Plant cover crops (also known as green manure) such as fava beans, peas, and vetch. They not only add nitrogen to the soil but also improve soil texture and water penetration, and encourage earthworms and beneficial microorganisms. While growing they provide habitat, nectar, and pollen for beneficial insects. Sow seeds of cover crops directly over the plot in rows 1 foot apart and about 3 inches deep; use 2 to 3 pounds per 1,000 square feet. Seedsare available from Harmony Farm Supply & Nursery (707/823-9125) and Peaceful Valley Farm Supply (888/784-1722). If temperatures drop below 20°, use mixes formulated for cold climates.

THE FOLLOWING SPRING:

After the cover crop starts to flower but before it sets seed (A), cut or mow it down and till it into the soil (B). (Don't use a rotary tiller for mixes that include vetch, since the plants will tangle in the blades.) After a couple of days, till again; allow soil to sit another two days before planting. Rake the soil smooth (C), then plant.