No-dig your way to success
March is the month to get your garden planting beds in shape for the coming growing season. March and April can bring more rain and downturns in temperature - though temperatures so far this year are on course to bring a record early spring.
Most plant growth is triggered by soil temperature, which is directly influenced by air temperature. When your garden soil temperature hits the mid- to high-60 degrees (F) expect spring and summer perennials, herbs, and vegetables to take off, whether you sow seed or set out transplants. Sonoma Valley soil temperatures historically climb into the upper 60s in May, but this year our soil temperature is already in the mid-50s.
(Soil Temperature Tip: You can take your soil's temperature by burying a simple thermometer six inches deep in the garden for about 10 minutes. Be sure to mark the spot.)
Getting the soil ready to plant - the no-dig or light-dig processWith the summer garden season less than eight weeks away, here is a simple and easy way to get your planting beds ready: it's called the no-dig or light-dig garden preparation method.
Here's how it works: prepare your established planting beds by breaking up lumps of soil and surface crusting. You can use a garden rake to do this. Then spread your soil amendments - aged compost, manures, and planting mixes - across the planting beds and let the spring rains and soil organisms - worms, natural bacteria and fungi - carry the amendments and their nutrients down into the soil.
You may want to double dig to a depth of 12 inches to establish new planting beds - especially if the ground is rocky or is predominately clay - but even that is not always necessary. Loosening difficult soil with a garden fork and spreading a couple of inches of aged compost or manure across the bed is more than enough work to prepare most gardens for planting.
Essential to the success of the “no dig” gardening philosophy is “sheet composting.” Sheet composting is the long-term maintenance plan for no-dig gardeners. Sheet composting simply means spreading several inches of aged compost and manure across the garden bed once or twice a year and then allowing nature - rain, wind and soil organisms - to work it into the soil. This method will save your back and does not disturb the natural habitat of garden microorganisms which are essential to good garden soil.
Simple no-dig planting bed preparation and improvementFollow these steps to prepare planting beds for the new season without much digging:
Use a garden fork - not a spade or rototiller - to loosen compacted soil in planting beds or to break up surface clods. You can do this in the fall, late winter, or very early spring. Avoid working in planting beds when they are too wet; you will inadvertently compact the soil; plant roots cannot thrive in compacted soil.
Spread two to four inches of aged compost across the planting bed; or spread one inch of well-rotted manure and one or two inches of aged compost across the bed. Let wind and rain work the soil amendments into the bed for a few weeks or even month or two. Then let soil microorganisms break down the compost and manure.
If you are ambitious, you can use your garden fork to lightly turn the compost and manure under after it has sat a couple of weeks. But it is best not to over-turn or over-till planting beds - too much digging and tilling can harm the microenvironment where soil organisms live.
If you use a tiller, run the blades slowly so that the soil life is not overly disturbed or harmed.
Mulch: Once the planting bed has been prepared, add another inch or two of aged compost or organic mulch across the bed. This will prevent the soil from losing much moisture and will protect the bed from air temperatures too cold or too warm until you plant.
Steve Albert is an author and California Certified Nursery Professional who lives in Kenwood. You can follow his gardening and cooking blog at harvesttotable.com.
Steve Albert is the author of The Kitchen Garden Grower’s Guide available at Amazon.com. He teaches in the landscape design program at the U.C. Berkeley Extension. He lives in Oakmont.