Garden Coach on Removing Grass with Little Effort by Sheet MulchingOctober 26, 2009
When I meet with a new garden coaching client, I always come armed with information on caring for lawns lawns in sustainable ways. However, these days I find myself pulling that information out of my client packets and exchanging it for information on how to remove lawns. Reducing lawns in favor of lower maintenance, more sustainable options has been on the increase — significantly so in 2009. Whether they’re looking for groundcover alternatives, new beds or just lower maintenance, sheet mulching makes getting there easy.
Fall is my favorite time to begin lawn removal programs. Why? Well, rain is abundant in the Pacific Northwest. And, we tend to spend less time lounging in the garden during the rainy season, so tearing up our lawn in fall doesn’t impact our day-to-day fun. Plus, at this time, soil microbial activity hasn’t come to a halt. So, by choosing to sheet mulch our lawns this time of year, we are able to opt for a passive removal method. We don’t break out backs with a lot of digging. We don’t run a fuel-hungry sod cutter or roto-tiller. And, we don’t have to find ways to get rid of the lawn we would otherwise dig out. Instead, the lawn nutrients are “tilled” into the soil by soil microbia, which convert this nitrogen rich organic material into forms ready for your spring plantings.
It may take a while for the garden life to complete lawn removal, but the life in the soil does the work for us during the months we’re unlikely to be using our garden. And, leaves are abundant! So, rather than putting them in yard waste or seeing them clog storm drains, collect them up and put them to use in removing your lawn and building beautiful, nutrient-rich new planting beds in time for spring.
Read more about how to remove your lawn and recycle its nutrient value into your garden here:Original Post from March 2009:
Irene G. of Sequim, WA writes:
“I am turning my mostly crabgrass lawn into a vegetable garden. I plan on putting about 4 inches of steer manure on top. that I will be getting the manure from a local dairy which has been composting for a few months. I was wondering if I could add any other amendments below the manure that will help break down the grass. I have about a month or two before I will be putting plant or seeds in the beds. Thank You for your help “
Irene, thanks for writing in and prompting me to write about a technique I really like for removing grass. The method is generally called sheet mulching. There are a few different ways to complete a sheet mulching project. My favorite method will follow, but before I share it, I do want to note that without seeing the site and assessing it completely, I don’t know that this is the right method for your space. For instance, sheet mulching on hills doesn’t always work well because things run down hill. Too, it does take a while for sheet mulched areas to breakdown completely. The soil microbes need to come and do a lot of eating. Ideally, I prefer to sheet mulch going into fall, but it can be done in spring, too. I do not sheet mulch in summer because sufficient water is necessary to keep the microbials working. I can say that if you don’t put something down between the grass and the mulch layer, odds are the grass will just grow up through the mulch.
Sheet Mulching Lawn Techniques
First, define the area that you want to breakdown and prepare into planting beds. Painting the beds with marking paint or laying out a garden hose to define your space may work. If you are sheet mulching a lawn area, cut the area of the lawn to be removed as short as possible using a mulching mower. Leave the cuttings in place and the living lawn in place.
If there are existing weeds in the area to be sheet mulched, it is a good idea to identify them to know their growth habits. Some weeds will be eradicated by sheet mulching. Some will survive the process.
If the area you are sheet mulching butts up to a sidewalk, deck, path, retaining wall, etc?it is good to trench out the lawn with a sharp edged shovel. To do this dig out the lawn about 4-8? from the edge of the adjoining structure into your sheet mulch area. Otherwise, the lawn may creep out of the edges where the lawn meets the structure.
**note that some cities require that you do not leave a curb edge open for liability issues; be sure to
check your city ordinances before beginning. **
Don?t throw out the cut out or trenched out soil and grass! Turn this upside down after you cut it, and let it breakdown over time. As it breaks down, it will add nutrients and materials back into your new beds. Water the area to be sheet mulched thoroughly.
Next add layers of overlapping, unwaxed, unpainted cardboard or thick layers of newspring to cover the area completely so that no holes are poking through. Remember: you are trying to block out all of the light to stop the weeds &/or lawn from photosynthesizing (aka making food/living). Do not use cardboard materials with colored inks, waxy or slick coatings; these may add toxins to your soil &/or be difficult to break down. If you trenched any edges, make sure that your cardboard wraps down into the trench and covers all the grass completely. If there are gaps, this can allow the lawn to creep through to the light and create weedy areas in your new beds. Water your first layer (the cardboard) well to jump-start the process.
Next apply a four to six inch layer of composted manure, leaf mold, amended topsoil, or other compost over the cardboard. How you determine your material may be based on availability or your plans for future use of the area and/or your existing soil type. Water this layer in well and keep it moist.
To expedite the breakdown of your sheet mulching area, keep the project area well watered. Consider applying compost tea to innoculate your area with soil microbia and get them working for you fast. (This will only work in warm weather; if it’s cold out, they’ll die or go dormant.) Worm castings from your worm bin will help, too.
Doing these steps will encourage microbial activity from the earth to move into your project area, and they do the work for you!
As well, you can overseed a sheet mulching area with a cover crop such as Crimson Clover, Ryegrass, &/or
Fava beans. Visit your local garden center for cover cropping/green mulch supplies. Be careful not to allow
your covercrop to seed your entire site.
The cardboard will keep the light away from the lawn, causing it to die back. The composted materials in the next layer will also keep the light down. As the grass dies, microbial activity in the soil will be encouraged to move toward the surface and will continue upward through the cardboard into the composted materials in this layer, drawing the mulched materials down into the lower soil levels, improving your soil structure and
nutrient values. The cover crop will keep weeds down. Some cover crops will ?fix? nitrogen, adding it to the
soil as it grows. All cover crops will add nutrients to the soil when yo u cut them down and turn them into your soil before you install your new garden.
Additional Critical Notes:
You may plant directly into the sheet- mulched area. However, keep in mind that every cut through the
cardboard opens a window to light, air and water that may allow the still living grass to grow through. It is
recommended that you wait a few months until the area has broken down. How long the process will take
depends on the existing soil structure, nutrients, water, sheet mulching compost or woody material, and
other related factors.
It is always recommended that all property be surveyed for any electrical, drainage or other underground
pipes, lines, etc?before you begin any project. In the US, call 1-800-424-5555 for location of your utilities.
It is always recommended that you check with any city ordinances, easements, setbacks, covenants, etc?
for any landscaping restrictions before you begin your project.
If you are building berms over the sheet mulched area, you may begin building them over the area you are
breaking down by adding additional amended topsoil over the cardboard. In situations such as this, it may
be best to add amended topsoil over the cardboard layer to your desired berm depth. You will need to water
everything in well so that the entire zo ne is evenly and consistently moist. Water these layers in well and top
dress the berms with a layer of mulch to about 2-4?. Water each layer well.
If you are working on a slope, newspaper layers tend to stick better than cardboard as your paper layer. But slopes are slippery, and depending on when you sheet mulch and the grade of your slope, you may find that sheet mulching isn’t an appropriate option.
For further reading on building effective berms.
And, please remember, this information is provided to help you get started. If you need help starting your project, please get in touch to schedule a garden coaching session with Garden Mentors.
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