To dig down or build up? That is the question! |

To dig down or build up? That is the question!

rosemary fills the raised bed behind a wall near steps in a Nevada City garden

This week the soil was soft from rains. Weeds were easy to pull.

A shovel or fork slid into foothill clay with little resistance.

As soon as unimproved clay soil loses this gift of moisture, the fine particles pack. Only where organic material has been added will the soil be loose and friable, in good tilth.

As I begin my 37th year of gardening on Sonntag Hill, I am grateful for every bit of compost and green manure I have added over the years.

If you are only now considering an edible garden, I would not be surprised to hear that raised beds are in your future. They do allow you to create an “instant” garden.

However, as you fill the raised beds with a compost blend, try to add some clay soil in the process.

One approach is to build shallow beds on top of the clay. Another is to purposefully add it to deeper beds. The clay soil is rich in minerals.

Soilless mixes may be fertile but often do not hold moisture. Nor do they have the rich blend of nutrients you can achieve by mixing your own. The first year’s growth of edibles may be excellent.

In subsequent years, the nutrients in a soilless mix will often be fewer than if clay soil was part of the mix.

Managing soil and soilless mixes continues each year. Cover crops add the “green manure” that builds organic matter. In the summer months, a quick-growing cover crop may be used, usually a mix of buckwheat and cow peas.

It takes only a few weeks of summer growth to have a good crop.

The premium soil builder mix at Peaceful Valley Farm & Garden Supply in Grass Valley is my favorite green manure or cover crop seed. It is complex, with several plants that will add organic material, available nitrogen, and minerals to your raised bed. Or in the open ground.

I have used this soil builder during the winter, allowing it to gain height in spring when growth is more active.

If I am transplanting tomatoes into the garden, I cut the cover crop and allow it to lie in place for a couple of weeks. No digging.

This method works in raised beds, too. Holes are dug into the cut cover crop. Rock phosphate, oyster shell and New Era Byodynamic compost are added. Use a handful of each, as all have been added previously for the cover crop. The tomatoes begin growing into the now inactive (but undisturbed) roots of the cover crop.

The cover crop decomposing acts as an early mulch for the tomatoes. The approach may also be used for peppers, eggplant, tomatillos and summer or winter squash. If the soil is too cold in May or June, pull aside this mulch for a few weeks. Warmer soil releases more nutrients.

If I am planting smaller starts, of lettuce, for example, a one-inch layer of compost is added to the bed to speed up the decomposition of the cut cover crop.

One to two weeks later, the starts are planted into the bed. This bed may also be used for planting seeds.

Animal manures add to soil fertility. Chicken manure is higher in nitrogen than horse manure.

Both benefit from the composting process. I usually order six to 12 months in advance of preparing beds for edibles.

The manure may be spread on the cut cover crop in late spring or it may be used before the cover crop is seeded.

If you are still harvesting when it is time to seed cover crop, try starting it in one-gallon containers, transplanting it to the beds when the tomato vines head for the compost pile in October.

While I am using the foothill clay soil on my property, the layering approach to add amendments may be used for raised beds. The goals are to minimize disturbing soil with digging and to maximize the organic matter.

Whether you dig down or build up, your goals are the same. Edibles grown in fertile soil will be healthier, more vigorous and definitely better for you to eat.

Correction: In my last article, a photo of “Red Cross” lettuce, a heat-resistant cultivar, was mistakenly identified as “eat-resistant.” Whoops! My error!

Carolyn Singer will be teaching a class on growing edibles in raised beds today at 1 p.m. at the Folsom Public Library. She has been gardening organically in Nevada County since 1977 and is the author of the award-winning book about foothill gardening, “The Seasoned Gardener: 5 decades of sustainable & practical garden wisdom”. For more information,

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