Sheet Mulch

 

Sheet Mulching is my favorite way to convert areas over 50sq feet from lawn to garden space.  Rototilling in the sod, as with any extreme soil disturbance causes significant stress to the soil ecosystem, which is already in a state of crisis in most suburban lawns.  Removing the sod is even worse due to the loss of what little ecosystem was in place, as well as the removal of significant amounts of organic matter that must now be replaced.  Sheet mulching allows you to kill the existing vegetation, be it lawn or weeds, while keeping the soil ecosystem and organic matter intact.  It is also a significant money saver as instead of purchasing yards and yards of topsoil, you are able to create it on site with waste products, and the finished product ends up better than anything you can have delivered anyhow.

This past summer, I had the oppurtunity to take a significant amount of lawn, 1000+ sq ft, at a client’s house and begin to turn it into a perrenial bed. Round-Up is not an option in my world, so I pitched Sheet Mulch and it sold. Here is a photo how to for a very simple, effective 3 ingredient Sheet Mulch with materials that are locally and readily availible here on the rural fringe of Suburbia: wood chips, cardboard pallet sheets, and horse manure.

 

Step #1 Prep the Ground

 

This plot had not been mown in months, so it took several passes with my electric mulching mower to knock down the turf grasses with the great result being a 1/2″ thick layer of mulched grass. The owner called them weeds, I called it a Green Manure crop!

Step #2 High Nitrogen “Starter”

In this instance there was a horse farm literally a block away from the home, but the edges of suburbia are speckled with horse farms. Some neighborly conversation can get you access to a trailer load of manure prebasted with straw/sawdust for near perfect carbon:nitrogen ratio. It sounds nasty, and it can smell alittle ripe, but use a long fork and you will be fine. I spread it about 2″ thick, but feel free to go as much as 4″. More than that and you might go anaerobic as oxygen will not be able to penetrate it.   2″ deep for 1000 sq ft took about 5-6 yards or 3 loads with my trailer. That’s alot of forking, but you can’t beat the net returns!

Step #3 Weed Barrier

I like to use pallet sheets. Most warehouses, and some retailers-especially those who carry alot of pet food or other bagged product, will have these in abundance. Again, do some calling and make nice to see what you can turn up. Newspaper 4-7 sheets thick works great too, but pallet sheets are ink free, and don’t blow around as much in the wind, plus each sheet covers 16 sq ft so you cover ground quick.  All natural carpet will also work-the trick is to cover the “Starter” with a breathable layer that is impenetrable to the plants below, but that will rot in a few months.  I overlapped mine at least 6″ on all sides so it took the better part of 100 pallet sheets. The manure is thick with oat and hay seeds, this layer will keep them and the turf grasses out of the bed.

Step #4 Weed Free Mulch

Every muncipality out here has a free mulch pile for its residents. This municipality even had a backhoe on hand to fill my trailer with 2-3 yards of chips in about 5 minutes! I made 5 trips in 2 hours. Check out that windrow!! And, yes, my shoulders were sore as hell after this… The garden will get a 6-7″ layer of this that will settle to 5-6″. Spoiled or marsh hay, straw, etc would also work, but spoiled hay is alot harder to find if you aren’t Ruth Stout, and straw typically costs money.  The thing on this layer is to make it Weed Free!  Wood Chips take longer to break down, but they don’t blow around much and are a perfect medium for innoculating with edible mushrooms!

Putting it Together

When sheet mulching I find it to be much easier to not let any one step get to far infront of the others. Get too much manure down and it starts to dry out, get too far ahead of the woodchipping with the pallet sheets and they start to blow away. Sheet mulching is a very satisfying to do, as the ground is covered very quickly and the sense of accomplishment is huge.

 

Tools of the Trade

I did this job, solo, in 10 hours start to finish, with the exception of having 60 of the pallet sheets on hand prior to starting. Here is a short list of some tools that saved me massive amounts of time, all of which are pictured above

1. Utility Trailer. Mine is 5×8′, cost under $700 and turns my Forester into a “pickup truck” extraodinaire, able to move 3 yards of light mulch with ease, or 2 yards of manure. Plus a trailer’s sides are 3′ shorter than a pickups so schlepping manure into it is much, much easier. Besides, when I don’t need a work horse I take the trailer off and the Forester goes back to getting 32 mpg vs a pickups 14! I love my trailer!!

2. Wheelbarrow. I purchased a mulch barrow for this job. $95 at TSC and it holds a whopping 10 cu feet. Even overflowing with manure I could lift it with ease-the balance is more Vermont Cart than traditional wheelbarrow with alot of the weight past the wheel’s fulcrum helping you lift the wieght. I have named it Archimedes, but often call it Hubris… A barrow this big is bound to get me in trouble…

3. Coal Shovel and Compost Fork. The Coal Shovel can move over a cu ft of mulch/manure at a scoop-mulch is light so it pays to move as much per scoop as possible. I picked it up at Menards for $16 as quality/design seemed simple. The Compost Fork is from Earth Tools and imported from Germany. It has a balance and feel that far exceeds anything you will ever find in a hardware store, and is worth every one of its $40.

4. Helpers! Many hands make light work; I had my uber energetic 5 yr old with me. True, the amount of work done by Sprout was minimal, but the diversion of someone to talk to was priceless, and mad props to him for keeping us both entertained for a full day as “Mr. Stone” keeping the cardboard from blowing away, or squealing anew everytime I dumped him out of the wheelbarrow on the return trip to the mulch windrow. Regardless of their age, someone to keep the weed barrier from blowing away is always a good thing!

The end result of a single days hard work will be taking 1000 sq ft of very sandy loam and covering it with an 8″ layer of organic matter. Through fall and into spring the soil’s ecosystem will kick into high gear with the manure’s nitrogen and eat away at the cardboard. The chips will also begin to decay-I see about a 25% decomposition annually in my paths at home. The net result by June should be a 2-3″ layer of ecologically alive compost covered by 4″ of wood chips-ready to plant!

Sheet mulching can be a great way to relatively easily turn lawn into garden-as long as you have several months before you want to plant. Those months are worth it if you can spare them: in addition to killing the sod, you keep the topsoil of your lawn, with all its ecology, intact, and add 2-4″ of topsoil in the process.

-Rob