Rosemary McCreary: Take small steps toward lawn replacement

Gardeners who want low-water plants in place of a lawn but feel frustrated by the prospect of tackling the entire project right now might consider the job less formidable if it’s broken down into seasonal steps, mulching then planting. After prepping the ground, you’re left with an open window for planting from tomorrow to next year.

It’s an old idea with numerous variations. The long version is called lasagna gardening; the short version is simply heavy mulching. It works for planting nearly any species, including natives.

The basic idea is to cover the ground heavily with a thick layer of anything that will turn into compost. Because light is excluded from existing plants — i.e., grass and weeds — they will slowly die. You can even snuff out ivy if you mow first and use a thick enough cover so that roots are starved of sunlight.

There are a couple of preliminary concerns, however, when converting a lawn to a bed for other types of plants. If you need to convert an in-ground pop-up irrigation system to a drip system for future plantings, mark their locations and replace heads with fittings that will accommodate drip lines before you proceed with mulching.

If you think you will be planting before a series of rains softens the ground, wet the soil before you begin so you’ll be able to dig a hole when you’re ready.

The bulk of the work entails covering the ground a section at a time with thick, broadly overlapping layers of wet newspaper or cardboard — no glossy colored paper — and spreading 4 to 6 inches of mulch on top. Use chipped tree trimmings or an inexpensive product from a landscape supplier. Later on, you can add a more decorative mulch if you want.

When you’re ready to plant, move mulch aside and cut through the paper or cardboard. If you begin planting shortly after laying out the mulch cover, the underlying grass or weeds will still be viable. In this situation, add more paper if needed to completely cover the area around the new plant and replace the mulch. The key factor is blocking all light from reaching undesirable vegetation underneath.

After the mulch has lain in place for about two months, most of the target vegetation will be dead. During very cool weather, however, it may take longer.

Garden lasagna

Gardeners who have ample non-woody trimmings on hand from fall clean-up or otherwise have access to quite a bit of organic debris could take a different approach in a smaller area.

By simply piling up compostables in a method that is variously called lasagna gardening or sheet composting, such a mixture will break down over winter and also decompose anything growing underneath.

Leaves, wilted annuals, trimmed perennials and grasses, debris from fruit trees and vegetable gardens, kitchen scraps, and manures piled up 1 to 3 feet deep and covered with a little soil or mulch will break down and enrich the ground below. Woody branches take longer, so keep those out. In spring, you can plant without even turning the soil.

Alternative method

It means more labor initially, but another method may be more appropriate if your soil is extremely dense or extremely porous and could benefit from considerable amounts of organic amendments.

To improve drainage, water-holding capacity, and fertility, mix organics into the soil rather than pile them on top the ground. Use one cubic yard of homemade or commercial compost for every 100 square feet.

If you turn under grassy turf or a weedy site in this process, it’s still necessary to cover the ground with newspaper or cardboard and mulch or the vegetation will reappear.

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Ready for an outing?

Here are a couple of promising possibilities. For a first-hand look at how a native plant garden survives in Santa Rosa with no irrigation, take a stroll through the pedestrian gate at the western entrance of the Pioneer Cemetery at Franklin and Monroe streets. The eight-year-old garden is located nearby, just east of the GAR obelisk, edged by a low fence along the cemetery road.

If you go now and then again in spring after they’ve had some welcome rain, you’ll see plants in their most stressed and their most pampered conditions. Labels identify one or two of each type of plant.

It’s time again for the Graton Community Club’s fall plant sale, craft sale, and flower show. If you’ve never been, it’s a chance to enjoy lunch or cake and pie in a very folksy, small-town setting. The clubhouse will be open 8 a.m. to 4 p.m. on Friday and Saturday, Oct. 23 and 24.

Rosemary McCreary, a Sonoma County gardener, gardening teacher and author, writes the weekly Homegrown column for The Press Democrat. Write to her at P.O. Box 910, Santa Rosa, 95402; or send fax to 664-9476.