By Laura Lovett, Gardening with Natives Committee Chair

 

cardboard

Lawns cover more acreage in home landscapes than any other plant and provide the least resources for other creatures. In most of California, a lawn will only thrive by irrigating it with expensive and often limited water. Consider removing your lawn and creating habitat by planting a more complex variety of species. If you include California native plants in that mix, your landscape will provide a thriving habitat while requiring less water, less energy, and no pesticides.

Sheet mulching is a great way to remove lawn, and fall is a perfect time to do it. Sheet mulching involves smothering your lawn grass in place with layers of compostable materials like cardboard, newspapers, compost, and mulch. The layers will compost and quickly become humus-rich soil that can be planted in a few months.Sheet mulch layers 2768039854

Chapter member Charlotte Torgovitsky has written an informative step-by-step guide on how to sheet mulch, available on the CNPS web site here. Those living in the service area of Marin Water can apply for rebates of up to $3 per square foot for lawn-to-landscape conversions that include sheet mulching, low water plants, and drip irrigation. Preapproval is required for this rebate; program details are posted here.

If you are thinking of reducing the size of your lawn or taking it out altogether, here are some useful tips:

  • There is no need to tackle the removal of an entire lawn at once. Removing small lawn patches and replanting that area before taking on another will spread out the work and the expense.
  • California native plants require a quarter of the water that a typical lawn does. To accommodate those different water needs, you will likely retrofit any existing irrigation system partially or fully. For new plantings, group together plants with similar water needs. Consider putting drought-tolerant natives on a separate irrigation system from remaining lawn areas and converting existing pop-up sprayers to lower pressure drip lines that deliver water directly to the roots of the plants. If you turn off a system but leave it in place, be sure to flag the location of the irrigation heads, so you can find them later through the layers of mulch. Consult with an irrigation specialist for advice, supplies, and information on the latest irrigation technology.irrigation conversion
  • The idea behind sheet mulching is to starve the grass of sunlight. Mow the entire area. Dig out stumps, roots, and heavy stems. Remove 6-8 inches of sod around all edges of the area you are converting, so you can bring the mulching layers right up to the edge with no grass visible. The sod you dig up can be tossed in the center of the composting area; it will break down with the rest of the lawn. To keep cardboard from lifting and letting sunlight in, anchor the edges with logs, bricks, or rocks.
  • Sheet mulching will kill most lawn grasses and ordinary weeds. To kill Bermuda grass, kikuyu grass, horsetail, blackberries, and oxalis you may need other techniques. See this article.
  • If you are keeping existing trees and large shrubs, cut cardboard so it will fit snugly up to the trunks, but do not mound any mulching materials against the trunk itself.
  • A LOT of material is needed to create sheet-mulch layers, so start researching sources ahead of time. Ask appliance and hardware stores for big sheets of cardboard; remove all plastic tape and staples. Collect autumn’s fallen leaves from your neighborhood. Ask local tree-pruning companies to dump a load of chipped branches in your driveway. Nurseries and home-and-garden stores may be grateful if you volunteer to haul away the bales of straw they used for display once Halloween is over.
  • Sheet mulch layers need to be moistened as you lay them down and while they are composting. If winter rains have not arrived or stop for a while, be sure to soak your mulched area weekly to keep the composting process going.
  • After sheet mulching, it is best to wait two to three months or more before planting herbaceous perennials. To plant trees or shrubs move aside the mulch layers, cut an X in the cardboard, and dig a hole in the soil below. Be sure to tuck the compost layers around the new plant, so sunlight is shut out.

Plan a sheet-mulched lawn conversion for this fall, and by late winter the microbial community should be flourishing and the layers you laid down turned to soil, ready to nourish your beautiful new garden.