Smart 'lasagna' gardening: Use your noodle to build a drought-resistant yard
Q: Due to the drought, I let my lawn dry up and would like to replace it with some native plants or low-water-use plants — ones that are attractive but don't use so much water.
Is there a smart was to convert my lawn to garden beds without digging up all the dead lawn grass? I'd like to start with weed-free beds if possible, and avoid using herbicides.
A: I commend you for wanting to remove your lawn for something more drought tolerant — and one that's more insect and bird friendly.
I would suggest you try a technique called “lasagna gardening” to convert your lawn to interesting garden beds for planting your new landscape. Lasagna gardening, also known as sheet mulching, smothers weeds while providing a raised bed for your plants. With this method you build the soil just like preparing a lasagna, one layer at a time. Then sit back and let nature complete the soil enrichment process.
By starting now, you will be able to plant in fall — when conditions are best for planting.
To start building your garden beds using this technique, you'll need to collect non-waxy cardboard, newspaper, manure from non-meat eating animals, grass clippings, leaves, compost, sawdust, etc. in large enough quantities that you can cover the area with each material at least one-inch thick. Consider laying out your beds with pathways between so that you don't have to cover the entire lawn area. Use a permeable weed cloth and decomposed granite, bark or gravel for the pathways.
Choose the area where you want to start and wet the soil thoroughly, letting it soak in overnight if very dry.
Then mow grass or clear off plants, and cover the area evenly 1-3 inches deep with manure.
Next, lay cardboard in a solid layer over the area where the grass was growing, making sure to cover all areas and overlap sheets by at least 6 inches.
Next add a mulch layer at least 6 inches deep. This can be a very thick layer up to 20 inches deep if you prefer. This layer will contain nitrogen-rich materials, such as non-invasive weeds or lawn clippings, manure, coffee grounds and kitchen vegetable scraps, and carbon-rich materials to cover this nitrogen-rich layer. The carbon layer is the dry things: wood chips, leaves, straw, sawdust, dead plants and pine needles. Make the nitrogen and carbon material layers roughly the same depth and have at least a 3-inch depth in each layer. On top of all the mulch, layer newspapers or other non- bleached paper, preferably four pages thick. Wet all the layers down well, and then add the planting layer.
For the planting layer, you can use a loam soil at least 4 inches deep. This planting layer will need to be 6 to 8 inches thick if you plan to transplant one gallon plants. You can finish off the bed with mulch or bark to keep the weeds down.
The bed building process can be spread out over time so that you build one layer one day and another the next. Or lay all the layers in one morning.
Whichever strategy you choose, make sure to keep the beds moist so that the organic materials break down and complete the bed a couple of months in advance of planting. In addition to suppressing weeds — or lawn grass in your case, this process builds rich fertile soil and helps conserve water in the landscape. The added organic matter holds moisture in the soil, which in turn conserves water — and as an added benefit it reuses materials that were probably landfill bound.
The Shasta Master Gardeners Program can be reached by phone at 242-2219 or email email@example.com. The gardener office is staffed by volunteers trained by the University of California to answer gardeners' questions using information based on scientific research.