With fall upon us, gardeners in cooler climates harvest the last of our produce as the growing season comes to an end. While it’s sad to see the end of our season-long bounty, fall is a perfect time to sheet mulch a new garden bed or bring an old one back to life in preparation for planting next spring.
Sheet mulching is a simple technique that builds the richness of the soil using easily attainable materials. By sheet mulching in fall, you garden will be ready for spring planting earlier and with minimal prep work.
Step 1: Select your Site
If you are starting a new garden, select a site that gets the right amount of sunlight for the types of crops you’ll want to plant. Will this be your main garden plot or a bed set aside for a one or two crops? It’s a good idea to decide what you are going to plant ahead of time so you select the correct site for your garden.
Your site could be right outside your front door, a forgotten corner of your property or anywhere in between.
Step 2: Gather Your Materials
It’s best to make sure you have everything you need to sheet mulch your site before you get started.
Cardboard - I pick up cardboard boxes from a few local restaurants and have asked family members save them. These sources have supplied all the cardboard I’ve needed this year, and then some.
Manure – This will be the main nitrogen source for your new garden. A farmer down the road from me raises sheep, so I have an ample supply of manure any time I need it. If you don’t have a farmer nearby, check your county fairground. During fair season, there should be an abundance of free manure and bedding. My local fairground also rents horse stables, which provides for free manure available year-round. Bagged manure can be purchased at many farm stores, but will raise the costs involved in constructing your new garden space.
If you don’t have access to, or want to pay for, manure you can also use freshly cut weeds, grass clippings or other green vegetation as a nitrogen source.
Wood Chips – This year my local electric company put a new pole on my property and they gladly unloaded the wood chips they had in their truck. Arborists and landscapers are also a good source for wood chips and are often happy to deliver them for free so they don’t have to pay to dispose of them elsewhere. Wood chips will be a carbon layer in your garden.
Compost – This will be will the hardest component to attain if you’re not already making your own. If you don’t have your own finished compost, you can use easily compostable materials as long as you don’t intend to plant right away. Since we’re preparing for spring gardening, this option is perfectly acceptable for this project. Bagged compost is also available at most farm stores.
Straw – Like manure, local farmers are a great source for straw if you happen to have one nearby with bales for sale. Otherwise, Craigslist is an excellent place to look for locally grown and baled straw. Farm stores and garden shops also sell straw, although at a slightly higher price. Straw bales are pretty easy to come by in the fall as they are also sold for decorations. Like the wood chips, straw is a source of carbon in your new garden.
Water – Pull out your garden hose so you can soak each layer as you go. The water will kick start the decomposition process.
Step 3: Prepare Your Site
I’m working with a site that my mother has been used for annual vegetables for the past several years. We have heavy clay soil in our area, which becomes as hard as concrete after even the tiniest amount of rain. She’s had decent luck growing her favorite bush beans, but not much else has thrived in this space. The new sheet mulch will provide a much healthier garden for years to come.
After picking the last of the bush beans and digging the few potatoes that managed to survive, I used the chop and drop method to clear the bed in preparation for the sheet mulch.
If you’re starting with a new site, all you need to do is mow or cut back any vegetation currently growing on your site. If your site has a lot of weeds, rather than pulling the weeds, chop them near the base and let them drop to the ground. This will provide an extra layer of nitrogen to your bottom layer.
Step 4: Lay Down Cardboard
With all the prep work behind you, the rest of this project is pretty simple, especially this step. Break down any cardboard boxes that aren’t already flattened and spread them out over your site. Be sure to overlap them by about six inches to combat any weeds that might try to make their way through the rest of the layers.
If you don’t have access to cardboard, newspaper can be substituted in this layer. Be sure to pull out the glossy print ads so the chemicals from the ink and paper don’t leach into your garden. You will need at least two or three layers of newspaper, overlapping as you go.
Step 5: Add a Thin Layer of Manure
Spread a half-inch to an inch of manure on top of your cardboard or newspaper. If you don’t have manure, you can use freshly cut weeds, grass clippings or other green vegetation.
Step 6: Pile On Your Bulk Mulch Layer
Straw is the easiest material to use for this layer as you’ll need eight to 12 inches of bulk materials. You could also use hay or stable bedding if either of these is more readily available in your area.
As I still have an abundance of wood chips and sheep manure, I chose to use of mix of the two for the majority of the bulk layer. I started with about six inches of the mixture, followed by a heaping wagon load of straw bedding from our chicken run. Then I topped it off with another two inches of the straw/wood chip mix. The combination gave me about ten inches for my bulk mulch layer.
Step 7: Add a Layer of Compost
Compost is an essential component for this layer if you plan to plant right away. Since we are preparing the garden for spring planting, there are some other options you can use in place of compost. Mixing soil and compost is one option, or you can add any easily compostable material since it will have a few months to breakdown.
Manure is yet another option for this layer. With only a small amount of compost completely finished, I decided to use some of the compost mixed with the sheep manure to reach the one to two inches needed for this layer.
Step 8: The Final Layer
Again, straw is an easy material to use for this layer and will provide the most appealing final touch for your garden. You can substitute wood chips, bark or leaves or any other organic matter as long as it is weed and seed free.
All that’s left is to let your new garden space rest for the winter.
When you’re it’s time for spring planting, lift off the your top layer and sow your seeds or plants directly in the rich soil your fall sheet mulching project created.
Material List for a 10’x10’ Bed
Cardboard – enough to cover your designated space
Manure – 2-½ wheelbarrow loads
Mixed wood chips and manure – 6 to 7 wheelbarrow loads
Straw – ½ bale plus a whole bale if using in the bulk mulch layer
Compost – ½ wheelbarrow load