Sheet mulching is a process that causes confusion for people, but it’s really pretty simple. The premiss is to lay down a layer of a light blocking, biodegradable material over an area, then cover this material with an appropriately thick layer of an organic mulch. This provides a clean planting bed and goes a long way to reducing weeds. An example of sheet mulching is probably the easiest way to see how it works.
(Click on any image for a larger version.)
The beginning
I’ll use our house as an example. When we moved into our house a few years ago it had typical landscaping. Most of the front was lawn, and to our eyes, it was also boring. The plants were all common landscape plants and not native to California. It looked so much like every other front yard, during the first few months we lived here, my wife accidentally drove past our house a few times because she had a hard time picking it out from the others.
We didn’t want lawn, for multiple reasons; water use and maintenance being the biggest. Our plan was for California native plants in the front yard to reduce water use, attract birds and provide a look we wanted. The first step we needed to perform was to get rid of the lawn. But how? Sheet mulching was it.
Step 1. Kill the lawn.
We knew we were going to plant California native plants and the best time to plant was during the rainy season so to begin the process of losing the lawn we just stopped watering it. We weren’t going to keep it and we were looking to save water anyway so we just turned off the irrigation. That killed off most of the grass leaving nothing to mow down before starting sheet mulching.
There was no need to dig up, pull up or turn over any of the turf. I liked that because it saved lots of work. All the other plants we didn’t want just needed to be cut down. Shrub root balls needed to be removed and I did dig out some of the agapanthus root just to keep them from coming back, but they were a pretty small part of the landscaping so that wasn’t such a big deal. Everything taken from the front yard was chipped up and composted to be put back into the soil.
Step 2. Block the light.
The next step was to put down the light blocking barrier. This layer prevents light from getting to any seeds that may germinate. The seed will send up it’s sprout, the leaves won’t find light and the plant will die and decompose back into the soil. This is why sheet mulching keeps any grass that survived from coming back. With no light, the grass runs out of energy and decomposes. There some bulb or rizhomeous plants that may have enough energy to make it through to the surface. These should be pulled or cut as they emerge.
It’s important to use a material for the light blocking layer that itself will decompose into the soil. Newspaper and cardboard are common choices. Not synthetic landscaping fabric! Since we had just moved, we had loads of boxes and the wrapping paper used to keep things from breaking so there was no lack of material for us. I’ve heard of people going to bike shops to get the big bike boxes because they cover so much area.
When using newspaper, multiple sheets need to be stacked together and it’s a good idea to get it wet so it doesn’t blow around. If any plants were saved in the landscape, the cardboard could have been wet too and it’s pretty easy to just mold the wet material around the base of any existing plants. It’s important to make sure there are no cracks or spaces where light can get in. When using boxes, remember to put something under the slits that form where the creases for the box flaps were cut. As you can see in the picture, I chose to put a bit of compost out over the cardboard, but this is not absolutely necessary.
Step 3. A clean slate
Once all the light blocking material was laid out over the old dead lawn and former planting areas, chipped wood mulch was laid over the whole thing. I wanted to be as reuse oriented as I could, so I got my mulch from Vision Recycling. The product I purchased included chipped up construction debris and materials from demolition sites. It sounded like a great opportunity to return some post consumer material back to the soil, and it’s a relatively cheap mulch product. Bark mulches are more decorative in my opinion, but this gets the job done just as well.
Keep in mind when you’re buying mulch in bulk, you may end up paying more in delivery charges than you did for the material.
Step 4. Ready for Planting
The mulch was spread in a 3-4″ layer directly over the light blocking material. (A mix of cardboard, newspaper and craft paper.) With the mulch applied, our new front yard was ready for plants. This is usually the part the confuses people the most. Yes, you plant right into the mulch. There are some considerations in plant selection when sheet mulching. Most seeds won’t do well in mulch. If you are looking to plant wildflower seeds, or (gasp) put down a new lawn, you need to use a different mulch material. A mix of compost and native soil is a good idea in those cases.
Our plan was to plant a drought tolerant California native plant garden. Most of the plants were in 1 gallon pots and would transplant well into the mulch. We did need to move mulch and dig into the underlying soil to get the plants to the right planting depth. When digging into the soil below the mulch, all that is necessary is to cut an X into the light blocking material. It’s not necessary to cut out any of the material. We also installed a drip irrigation system that sits below the mulch so it’s not visible when you walk by. The extra pile of mulch in the left of the picture is waiting to be moved into the back yard.
The end (almost)
A year after planting, the plants are becoming well established. It looks sparse, but the plants keep getting bigger and fill in more and more. This is the end, almost, because plants are continuously being added. It’s not necessary to plant everything at once. We have been trying different plants, and have moved some. We will continue to add plants until the garden looks the way we want. We could have done all the design work up front and planted according to a plan, but our choice here was to fill in the plant pallet over time.
Once our lawn was gone and our California native plant landscape was installed, my wife never drove past our house again. It’s distinctive. There’s no lawn to take care of. It saves water and energy since there’s no green waste to be hauled off to a composting facility. (Of course if there were any, it would get composted on site, but not everyone composts. Yet.) We have created a habitat for local birds and beneficial insects. The garden is also more appealing to us. It looks nicer and the smells of the sages and coyote mint add and extra dimension.
One final but not insignificant benefit, as the mulch decomposes, it helps improve the overall soil condition. I’ve heard many complaints from people about our valley clay soil. How it gets thick and mucky when wet and hard as concrete when dry. Just over a year after sheet mulching our front yard, the soil is much less compacted and absorbs water way better. I made a video of how water infiltrates the soil in our front yard as compared to a neighbor’s house. You can see it here.
Sheet mulching also works in weed infested or neglected areas you’d like to reclaim for a garden. Sheet mulch the area, lay out any irrigation, add plants and you go from blight to garden in a matter of days. If you’d like to get started with a clean slate instead of a lawn, check out our lawn replacement service or get in touch with us and we can do it for you. If you have a garden you’ve transformed, share your experience with us.
