Fall is a great time to begin new garden beds so that things are primed and ready to be planted come Spring.
Starting a new bed can be intimidating if it involves digging up all the grass, tilling, and going through other heavy-duty preparations.
What’s the easier solution? Sheet mulching!
Also referred to as lasagna gardening, sheet mulching is basically composting in place. Instead of digging up the ground and adding soil amendments, you create a new garden bed by layering soil-building materials right on top of the ground.
But what about the grass or weeds that are already there? They get covered with a layer of newspaper or cardboard that acts as a weed protecting barrier that will kill the grass or weeds. They will just turn into compost along with all of your other additions.
Sheet mulching is really very forgiving. I think the two most important steps are to: 1) Make sure the ground is covered with newspaper or cardboard to kill the grass and prevent weeds, and 2) Pile on a lot of organic matter. This will get you started with the essentials for a new bed. The more amendments you add right away, the healthier the soil will be that you start out with, but don’t be afraid to start with whatever you’ve got.
Toby Hemenway details the process for a “Bomb-Proof Sheet Mulch” in the excellent book, Gaia’s Garden: A Guide to Home-Scale Permaculture. This is what you want to do and the amendments you want to add for the most nutrient-rich, awesomely composted soil come Spring.
- Water the site to be mulched the day before, unless the ground is already wet from rain.
- Clip, mow, scythe, or weed whack the area, but don’t pull up the weeds or remove the grass.
- (Optional) You can add soil amendments at this point. Sprinkle lime on acidic soil. Use gypsum or sulfur for alkaline soil.
- If you have compacted or clay soil, it can be broken up a bit. Don’t feel that you need to turn the Earth, just stick a fork into the ground and rock it around to allow better moisture and root penetration.
- Add a thin layer of high-nitrogen material like manure, blood or cottonseed meal, fresh grass clippings or other deep green material. This is not an essential layer, but it will help to attract worms and beetles that can help to loosen and aerate the soil.
- Lay down newspapers and /or cardboard to smother the plants that currently exist. Try to overlap the sheets so that weeds and grass don’t sneak through. Spray water on the sheets to help them break down and to prevent them from flying away in the breeze.
- Do another thin layer of high nitrogen material (manure, bloodmeal, etc.).
- This is where you’ll want to create a really thick layer of bulk mulch. About eight to twelve inches of straw, hay, or other mulch materials such as yard waste, leaves, stable sweepings or wood shavings. Grass clippings work too but should be mixed with other “brown” mulches like leaves so that the high nitrogen content doesn’t result in smelly, anaerobic decomposition. Without getting to worried about it, try to aim for a Carbon:Nitrogen ratio between 100:1 and 30:1 in your bulk mulch layer. Spray water occasionally as you build this layer. It should be damp, but not wet.
- Top this mulch-rich layer with an inch or two of compost. If this much compost is hard to come by, it can be mixed with soil to stretch it farther. Manure or other easily compostable material could also be substituted if the site will have a few months to decompose before planting.
- The final layer is two inches of weed- and seed-free organic matter: straw, fine bark, wood shavings, leaves to create a more “finished” look.
We have lots of new beds we want to establish on our farm, and we are excited to plant many more vegetables and herbs come spring! So we just did some pretty simplified (i.e., not quite bomb-proof, but I’m sure close!) sheet mulching to get started. We can always add more amendments as they come to us (we just need our chickens and goats!).
For ours, we basically just used a layer of cardboard to block out the weeds and grass, added a thick layer of grass clippings + yard waste + leaves, and added a final layer of leaves to finish everything. Ideally, we would have added more manure and/or compost to the layering, but we were working with what we had on hand. If some shows up, we’ll add it later!
We were left with a nice, fluffy new bed that will decompose into a new garden space come Spring.
We also started the same process in front of our house to create a medicine wheel garden. This will be divided into four quadrants with medicinal plants that correspond to each direction. More on that some day!
If you’re inspired to get busy this fall with all of your extra mulching materials, here are some other links that explain the process. I’d also really recommend the book noted above, Gaia’s Garden, for a great introduction to many aspects of homescale permaculture.
Happy Sheet Mulching!