Lasagna gardening (also called sheet mulching) is a method of making soil and compost by building up layers of organic materials. It is often used for turning a grassy or weedy area into a nutrient rich garden space. The essential idea behind lasagna gardening is the layering of several types of organic materials such as food waste, manure, grass clippings, compost, dried leaves, mulch, etc., right where you plan to plant your garden. There are many variations of this method out there, but they will all get you to essentially the same place – a garden bed filled with nutrient rich compost, that retains moisture and suppresses the growth of weeds underneath.
The Layers of my Lasagna Garden
The layers are similar to those found in a backyard compost bin – layers of green (nitrogen) and brown (carbon) materials that break down over time to create compost. I used a lasagna garden in my yard because the area where I’m growing some raspberry bushes has very poor, clayey soil. So, I decided build up the soil around where I had planted
1. Slashed Vegetation
I started by cutting down the pre-existing vegetation on my site. In my case, this included grass and weeds. I spread out these materials evenly as the first layer of my lasagna garden. I also added some food waste that I had originally been saving to add to my compost bin. You can also add some soil amendment at this point, such as dolomite, blood meal or gypsum.
2. Weed Barrier
The second layer is the weed barrier, which can be newspaper, cardboard, hardboard, old cotton clothing, etc. I broke down several boxes that I had been saving to be recycled. If using cardboard, make sure all tape is removed.
This layer is important if you plan on placing your new garden space over top of a grassy or weedy area. The layer will breakdown over time and be incorporated into your lasagna garden. If you have some plants that you would like to keep in you garden (like the raspberry stalks that I planted last year), layer the weed barrier around the stem. Water this layer thoroughly before adding your next layer; it will start the process going.
3. Nitrogen Source
Next add a 2-4 inch layer of nitrogen-rich materials (i.e. green stuff). This may include grass clippings, shredded green leaves, horse/cow/pig/sheep manure (do not use dog or cat feces), etc.. I used fresh grass clippings. Water this layer thoroughly before adding your next layer.
4. Carbon Source
Next add a 2-4 inch layer of carbon-rich materials (i.e. brown stuff). This may include shredded leaves, shredded paper, compost, peat moss, straw, sawdust, etc. I used a layer of peat moss. Water this layer thoroughly before adding your next layer.
5. Nitrogen Source
Add another layer nitrogen-rich materials. I used a couple bags of composted sheep manure. Water this layer thoroughly before adding your next layer
6. Carbon Source
Add another layer of carbon-rich materials. I actually made two layers for this one – a layer of shredded leaves, followed by a layer of compost from PV Waste Solutions in Regina. Water this layer thoroughly before adding your next layer. After adding the compost layer, I decided to finish the edges with some reused brick I had in my yard. Bordering your lasagna garden is not necessary, I only did so because I’ve been trying to find ways in which I can use these bricks in my garden.
7. Cosmetic Top Layer
This is your final layer and is often shredded leaves, wood chips or mulch. Again, water this layer thoroughly. I used shredded leaves because that is what I had on hand at the time. However, when this begins breaking down it will shrink down in size several inches. At this point I will likely add another layer of compost on top of the shredded leaves, and then a final layer of wood chips to finish it off.
Now you’re done and have successfully created a lasagna garden. Your layers will be 1-2 feet tall or so, but it will shrink as the materials break down and are absorbed by the soil. In a few months, your soil should be well fed and crawling with earth worms. If you used cardboard as your base, you may find it hasn’t completely broken down yet. That’s okay. Just cut through it to plant your garden bed.
You can make a lasagna garden at any time of year as long as you can get the necessary ingredients. However, in colder climates like Saskatchewan it is best to build the layers in the fall to take advantage of fresh grass clippings and fallen leaves. However, you can also create a lasagna garden in early spring and be ready to plant in early summer.
May 27 – Update:
The layers of the lasagna garden have already started to decompose since we built these layers on May 8, three short weeks ago. If you look closely, you can see a little sow bug crawling through — one of the many organisms contributing to the soil web of life.
Green Guerrilla Sustainability