Sheet Mulching: The Best Way to Turn Turf Grass Into a River-Friendly Garden Space

Learning to sheet mulch was part of the home gardeners’ hands-on experience at The Garden on Eden’s. Sheet mulching is one of the easiest ways to convert a lawn to a water-wise garden. Compared to physically removing the old lawn, sheet mulching is less work, less expensive, and doesn’t involve the use of machinery or toxic chemicals. It is a process of composting your lawn in place. Over time, sheet mulching improves the quality of the soil and provides a welcome environment for beneficial insects, worms, and micro-organisms. Getting started is easy. Just follow these steps:

1. Measure the lawn area to be sheet mulched. You’ll need to know how many square feet so you can get the right amount of materials. For every inch of depth to cover a 10’ x 10’ area (100 square feet), you will need 0.3 cubic yards (8 cubic feet). It takes 27 cubic feet to make one cubic yard. Landscape supply companies can also help you calculate how much compost and mulch you will need, you may want them to deliver bulk quantities to save time and effort.

2. Water the lawn sufficiently to get the first 4-6 inches of soil wet. One or two normal irrigation days should do it. Water at least 24 hours in advance of mowing because you don’t want to mow the lawn when it is wet to avoid compaction.

3. Mow the lawn as short as possible and leave the clippings where they fall. This may be the last time you will need your lawn mower!

4. If your lawn is adjacent to pavement, remove a minimum of a twelve-inch (12”) wide strip of the lawn along the pavement. Do this with a shovel, digging down approximately six inch (6”) or the total depth of the sheet mulching materials when the process is completed. This will keep the sheet-mulching layers from overflowing onto the pavement.

5. Add well processed, healthy smelling compost to a depth of one- to two-inches (1 - 2”) directly on top of the lawn, spreading it with a rake so the compost is evenly distributed. The green lawn blades and compost will provide nutrients to help decompose the lawn. Water the entire area until the water soaks down to the lawn. This will get the composting process going.

6. Install a layer of cardboard over the entire area. Overlap each row by approximately 6”. Rolls of corrugated cardboard can be purchased for this purpose. Other options include: using large flattened cardboard boxes (remove all wrapping tape) or ten (10) layers of newspaper. The cardboard will smother the lawn and any weeds. Do NOT use any type of permanent barrier such as plastic or weed fabric. Secure the cardboard with metal landscape staples (u-shaped pins to hold the cardboard in place).

7. Add a four- to six-layer of mulch (preferably arborist mulch, which is a mixture of all parts trees and plants chipped and various sizes) on top of the cardboard, as the final layer. This layer along with the cardboard will keep the mowed lawn/compost from drying out so that the lawn can decompose.

8. In the dry summer time, check under the cardboard once a month and if dry, water to keep the composting process going. Wait about three months before planting to ensure the lawn is both dead and composted before planting. (Note: This period of time can vary depending on the season.)