Killing grass to make a garden
Can I do something now to prepare for a garden this spring? Is there something called sheet composting? Do I put down newspaper, wet it, then put top soil or compost or mushroom soil on top? Would it kill grass and decompose and be ready for plants in the spring? Thanks! Jo Anne
New Castle County Delaware
Sheet composting or mulching will work as well as will some other methods described below. In all cases a soil test is recommended before planting. You can get the materials for the test at the U of D Extrension Office in Newark.
- If you are not averse to using chemicals you could spray the area with a broad spectrum herbicide - being very careful to avoid any desirable plants, and doing so on a windless day to avoid chemical drift. This is the only technique that does not involve mowing the area first. You want to have as much plant material as possible to absorb the herbicide. Once all of the grass is dead you can simply till it into the ground and it will become organic material in the new garden.
- Mow the area as short as possible, leaving the grass cuttings. Simply cover the area with about 6-8 layers of newspaper, wetted down, and then tarp the whole area with a (preferably dark colored) tarp. Do not use plastic bags - they will cut out all air and water, and kill any beneficial soil organisms! This method takes a couple of months, at least, to kill all of the grass but it is environmentally friendlier. When you are ready to plant, simply roto-till the newspaper into the old sod.
- A complete description of sheet mulching is in this link. http://extension.oregonstate.edu/lane/sites/default/files/documents/lc731sheet_mulch_lasagna_composting.pdf
- You could use a sod cutting machine, or a flat-nosed shovel to scrape the existing grass off. You will not get all of the roots but tilling the area will uproot and expose most of the old roots which will die off eventually. You should bring in a layer of garden soil and composted manure if you use this method. Till it all into the planting area. On the other hand, if you don't mind waiting to plant you could simply strip the sod off, till the area and replace the sod strips - upside down - over the whole area. This would retain the soil and add even more organic material to the planting bed. Next year you would want to add a layer of composted manure and till again, in order to incorporate the dead sod.