Sheet Mulching: How to Build Soil & Save Water
What is sheet mulching?
Sheet mulching is an easy and fast way to replace a high maintenance water sucking lawn with a thriving garden. It transforms soil quality through the natural decomposition process via a biodegradable substrate layered over a patch of lawn or weedy area.
It provides a blank pallet of rich and fertile soil to plant a garden on and allows for easy layout of garden features like a drip irrigation system or a large plant(s).
I used sheet mulching to replace both my front and backyard lawns with a garden. I did it in increments until I slowly replaced all the grass. I experimented with when and how I applied the sheet mulching to figure out what worked best.
My overall conclusion is that if you follow the general principles of sheet mulching, you will be fine. It is not necessary for you do it exactly like I do or some other source that you may be using.
At its Simplest
Sheet mulch at its simplest is really nothing more than a layer newspaper, a layer of cardboard topped by 10” of an organic mulch (leaves, hay, straw, woodchips, compost etc.).
So, it is up to you. You can do it exactly as I do, or you can experiment with what you have and where you are sheet mulching. What is important is to create the best environment possible that promotes healthy composting.
Pro Tip: Start Small. Approximately 200 square (20’x20’) feet but you can most certainly go smaller if you want
However, with experienced leadership and a big enough crew, you can accomplish transformation quickly.
I first learned about sheet mulching when I volunteered for the annual permaculture project, The Village Building Convergence in Portland Oregon.
Our team of approximately 20 people were tasked with turning a section of a church’s city lot into a garden. The soil had been neglected and needed restoration, but we only had a day to get something done.
First we spread approximately 2” of compost over the old lawn and covered that with a layer of newspaper, cardboard, approximately 4” of wood chips and topped it with straw.
We used sheet mulching to quickly turn that lot into a garden in less than eight hours.
When to start
The decomposition process takes time even though sheet mulching accelerates it. I have found it best to sheet mulch an area months before you plan to plant it, preferably in winter.
I do a lot of my garden planning in the winter and when I sheet mulched my yard I always did it in early winter, so the winter weather helped it stay moist and in place. By following this tip, by Spring you will have rich fertile soil to plant your garden in.
What you will need
Just to repeat, you do not need all the items listed below. You can make do with newspaper, cardboard, and organic mulch. However, if you want to maximize your soils potential here is what I recommend.
- Newspaper
- Cardboard
- Compost: Manure, vegetable waste, grass clippings etc.
- Woodchips
- Topping: Straw, mulch, pine needles, leaves, etc.
- Soil Supplements (Optional): See Below
Prep the Area to Be Sheet Mulched
NOTE: The day before you sheet mulch soak the area with water.
After the water has been given a day to soak in you will want to cut or mow the area and clear it of all unwanted or invasive plants.
If the soil is compacted use a spading fork to open the soil up by making small holes that allow better moisture penetration.
The goal is to make the area flat and clear of debris (stumps & wood), so that the sheet mulching lays smooth and flat.
Pro Tip: Don’t pull vegetation up, instead cut it short and let it become part of the decomposition soup
Soil Supplements
Next add soil supplements but first it’s important to understand what kind of soil you have. You can use a soil test kit like one of these to test your soil, so you will know which supplements are right for your soil.
Additional supplements to consider.
Phosphate: Bonemeal
Trace Minerals: Kelp meal or rock dust
I simply mix the supplements together in a bucket and sprinkle them over the area to be mulched. If you have any questions about your supplement always follow the manufactures instructions for proper application.
Larger Plants
If you have large plants (5-gallons or bigger) that you are going to add to your garden design now is the time to get them in the ground before you start sheet mulching.
Next….
I add a thin layer of manure. Any well decomposed compost will do.
Most of the soil I have sheet mulched has been compacted so this thin layer of manure attracts worms and burrowing beetles that aerate and loosen the soil.
Weed Barrier
This is where the newspaper and cardboard boxes come into play. You will find that many grocery and big box stores are happy to give you their excess cardboard boxes. Be sure to only use cardboard that has had its staples and tape removed. If this is not an option for you, you can purchase rolls of recycled cardboard that work well.
Newspaper
Use only black and white non-glossy type newspaper. Working across the area to be mulched spread a layer of newspaper. Spread it out generously so it is 2-4 pages thick and overlaps in all directions. The goal is to create an uninterrupted light blocking layer that will smother any new plant growth.
As you lay out a section spray it down with water but avoid walking on the wet paper, so you don’t pull it loose from the soil.
Cardboard
Cardboard is easy to work with, the bigger pieces cover a lot of area quickly and it’s easy to cut it into specific shapes to accommodate weird spaces.
You will again work your way over the area and cover the newspaper you just laid out with cardboard. Be sure to overlap the pieces by at least 6” to reinforce the uninterrupted light blocking layer you created with the newspaper.
As you get a section of 3-4 pieces of cardboard laid out to your satisfaction wet it down with a hose. This will hold the cardboard in place and makes it easier to modify if necessary. Be sure to spray the cardboard several times to ensure the water penetrates to the newspaper below.
Pro Tip: Do not be frugal with the carboard. Cover every inch of lawn that you intend to convert to a garden and if you have extra carboard double up in any trouble areas.
Woodchips & Compost
Next, over the cardboard lay down a 3”-4” layer of woodchip and then cover the woodchips with a 1”-2” layer of compost.
Topping
Finally top the compost with 6” of loose straw. I have a lot of leaf’s on my property so I mix them in with the straw but as I mentioned in the materials list above, other substrates like hay, mulch, pine needles and, leaves work fine too.
To finish it off I usually spindle a layer of compost over the top to hold everything in place
Small Plants Last
Now you can finally add the smaller plants. If you are doing the sheet mulching in the winter, you may want to wait until spring to plant anything that might die in the winter cold.
And if you did mulch during the winter you will have a spectacular soil to start a vegetable garden in
The Maintenance of Your Sheet Mulching
You have done a lot of work building your decomposing layered sandwich so make sure you follow these few tips to ensure you get the results you want.
Hidden Agenda
I will admit I have the hidden agenda of why I want you to replace your lawn with a garden, because it saves water. Sheet mulching is my decomposing Trojan horse.
It is all about the water.
Lawns are wasteful and silly. They are a leftover from an area when it was considered a status symbol to have a ‘nice’ big lawn. It is a fallacy. A lawn can became an obsession with cutting, trimming, watering, edging, weeding, and fighting the gophers. Not to mention they are a lot of work, take a boatload of maintenance and lawn mowers pollute.
And for what? A higher water bill and the momentary thrill of upping the joneses.
I would rather have what a garden provides me such as fruits, veggies, herbs, and ornamental flowers. Also, grow in my garden insectary flowering plants that attract, feed, and shelter beneficial insects including bees.
Use Drip Irrigation
Using a drip irrigation line is the best way to minimize your water consumption but still effectively meet your plant’s watering needs.
The best time to layout a drip irrigation system is after the mulch has had a chance to settle and before you begin planting anything.
Drip system kits are inexpensive and easy to layout and install. There is a huge variety of options with sizes to fit any garden, click on any of the images below to se what a kit includes.
Also check out my blog post on Greywater Harvesting to create a low cost source of water for you irrigation needs and my other post on How to Use a Garden Planner for ideas of how to layout your system,
It is always about the water.
You know you want to sheet mulch that part one part of your lawn, especially that part that you are sick and tired of taking care of.
Transform that water sucking lawn into a productive garden!
Do it, I dare you.
Plant a garden and the earth pays you back with food and beauty.
I vote Earth every time.
Check out the blog articles below for other ideas on how to save water.