by Dawn W. Todd, Nursery Volunteer
I am shocked and appalled at the number of people who don’t know how to make lasagna. It’s simple, it’s easy—far easier than the alternatives—and it’s so good for you! I don’t mean the kind of lasagna you eat, of course. I mean the kind of lasagna that saves the true lazy gardener from the back-breaking toil of weeding, yet keeps the soil rich and makes your beds look cared for. It is an ancient technique, sometimes called sheet composting, sheet mulching, or cold composting. It works because weeds need love, too. At least, weeds need light and air just like other plants.
I know the right way to do it, and I will let you know, too. I don’t always do it that way, because I don’t have enough sun to raise vegetables anyway, so I’m not very fussed about the nitrogen component of my future garden bed. So far the kinds of things I plant seem perfectly happy, but you must do as you think best.
Here’s what I do: I figure out where I want a garden bed, or where I used to have a garden bed before I lost interest in weeding last summer. I grub out as much of the bindweed and buttercup as I can stand to grub out, or perhaps I mow it or use a grass trimmer to level it a bit.
Then I go to my local pet food store, because the woman who manages it knows me and lets me raid her recycle container. Her recycle container has large, flattened, plain (unadorned with ink) cardboard boxes. I take them home and I put them on top of the area that I want cleared. That’s the first layer. Then I put a few inches of wood chips on top of that. In a few weeks, there might be a buttercup poking through, and I grub that one thing out. (I have heard that chickens are a potential solution to buttercup.) Or, if I have lost interest and wandered away for too long, I lay yet another layer of cardboard, topped with another layer of chips. That’s it.
It looks pretty good. A lot better than the weeds, anyway, and I can cut a hole in it to plant a shrub if I want to. In a month or two (or maybe three) it is lovely soil, no trace of cardboard whatever. The wood chips break down, too, but not as fast as the cardboard, which is fine with me. I do this in the spring, because you know how it is; it’s cold in winter, nothing much is happening outside, and then suddenly it’s spring and there is an explosion of green and one can’t find one’s lawn furniture.) If I think of it, I might toss some cut grass on top of the cardboard, too. As long as the layering is done while it’s still raining, it will result in a cleared space with decent soil.
I also do it in the fall. Right now. The beauty of it is that it’s raining (essential to get that cardboard wet) and it looks tidy, and it stays looking tidy until once again we are overcome by spring. The other good thing is that one’s foolish neighbors keep bagging up their nutrient-rich leaves for disposal, and it’s a simple matter to grab a bag and spread that down on top of the cardboard, and the wood chips on top of THAT. The only time you really cannot do sheet composting is in the summer when it’s dry, unless you want to spend all that time and money watering it.
How does one do it correctly? To do it correctly, one must use alternating layers of carbon sources (the wood chips) and nitrogen sources (things like kitchen scraps or manure). Here is an article from the Oregon State University Extension Service with more detail:
Remember that the folks at the Kruckeberg Botanic Garden know a lot about gardening and what plants need. When you visit you can ask about your own particular garden mulching projects and get advice.