Soil: Weeding by Sheet Mulching

Sow thistle

For this next part of how to build soil by weeding, I’ll discuss one of the easiest and laziest ways.  If you want nothing to grow in an area, and don’t care about how it looks or length of time, then sheet mulching may be for you.  I’ve used cardboard and newspapers around my vegetable beds with great success.  To fully knock out tough weeds such as Bermuda grass, you should put down a good inch of newspaper or cardboard (or a combination).  If you are using newspaper, leave the sections intact or else the wind will blow it everywhere, or cover it with a piece of cardboard.  Water it in and let it rot.

If you have old plywood lying around, drag it over to your weed patch and pop it on top.  Walk over it all you want, just watch out for old nails.

Sheet mulching with plywood... at work!

Another method is to water your weeds, then cover them with thick black plastic held down with rocks.  On hot days the weeds will cook under the plastic.  I’ve used this before successfully, but now I would only use it if I had the plastic already.  I’m trying hard to not contribute to the creation of more plastic.

The area after the plywood was removed.

Then there is sheet mulching where you actually build your soil over the top of weeds.  The new catch-phrase for this is lasagna gardening.  Start with a layer of corrugated cardboard or three layers of newspapers (or a combination!) right on top of your weeds and where you want to plant (this isn’t for clearing pathways). Water this in really well.  Then gather together compost items such as coffee grounds, weeds (without seeds), grass clippings, shredded paper, seaweed or algae… whatever you can compost.  Sort your compost into browns and greens.  Browns are mostly dead stuff such as leaves, shredded paper, pine needles and dried plant clippings.  Greens are fresh things like dinner scraps, green cut grass… anything with some life still left in it.  Manure is perfect for your ‘greens’ pile.  Chasing down landscapers as they rake leaves and bag up grass from their lawnmowers is a good way to collect ingredients.  Now start layering.  The best ratio would be two parts brown to one part green, but don’t stress over it.  The green stuff will heat up and cook the browns.  Depending on how much stuff you can layer, your bed should be about two feet high, and however long that you want it.  Water it regularly.  Within weeks your lasagna will have sunk down into fantastic garden soil.  If you want to plant right away, then add several inches of compost to the top.  Otherwise, let it sit a season and you’ll be able to plant right into it.  The newspaper or cardboard at the bottom will help suppress weeds and keep it moist.  Remember that the deeper your loam, the more rainwater it will hold and the less you’ll need to water.

What all of these methods of weeding does, is to decompose the weeds right where they are.  The minerals that they hold in their leaves are distributed into the soil, and as their roots decompose they leave tunnels for worms and other soil creatures to move around in.  You are keeping the soil moist and dark, which are wonderful conditions for our soil friends to flourish.  I’ve left plywood down on pathways during the entire growing season, and when lifting a piece have discovered treasures such as newts and salamanders underneath, that I wouldn’t have seen otherwis.  They are great bug eaters for the garden.  Sheet mulch also can harbor slugs and ants, but they are easily dealt with, especially if you have chickens!

Sheet mulching is very easy, it combats even tough weeds, it builds soil, and it repurposes things you might normally put into the trash.  So save all those boxes from Christmas, the contents of your paper shredder, what newspapers you didn’t use to light the fireplace, your garden waste, your kitchen waste, and whatever your neighbors want to get rid of (tell them you’re making lasagna with it!) and begin layering.  You are helping your garden, helping your soil creatures, building loam, opening underground stores of minerals for usage by plants, making your fruit and vegetables rich with nutrition, lightening your impact on the dump, creating a beautiful garden, and all without backbreaking work and certainly no chemicals!  Just say, “NO!” to Monsanto!