Sheet mulching or lasagna gardening, is like composting in place. The process can take three to six months, but the finished compost does not have to be hauled. It suppresses weeds and builds fertile soil.
Sheet mulching or lasagna gardening is layering various compost material on the ground. A sample picture of this is shown above. The goal is to attract worms, build fertile soil, kill out any existing weeds, cover existing seeds so deeply that they can not germinate, and basically start a garden area from scratch with a clean slate.
I have a garden out at my farm. It was there when I bought the farm and it has all kinds of tall prickly weeds that come up every year. Last year I put a tarp over one section of the garden and weighted it down. It prevented anything from coming up in that particular area, but if I simply remove the tarp, the weed seeds will germinate and I’ll have issues again. Sheet mulching or lasagna gardening will solve my weed problem and pump life into the soil that will help my garden plants grow strong. I actually started on the project this past weekend. You can see in the picture titled “Sheet Mulching or Lasagna Gardening” where my father-in-law is watering the soil and in the back quarter of the fenced in area we already have an inch of manure down.
I’m Thirsty, but Don’t Drown Me
Before we get into the sheet mulching steps, lets talk about water. You need to add water at several steps throughout the sheet mulch process. The water is to keep the soil life happy. But how much water. You don’t want to drown your soil life. The basic guideline is as wet as a wrung out sponge. By this I mean, if you take a kitchen sponge and thoroughly wet it and then wring it out, the water just flows out. What you are looking for is what a sponge is like after it is wrung out. It is wet, but very little or not water comes out. The optimum wetness is to get one drop of water out. Taking this back to the garden, if you wet your organic material, let it set for a couple of minutes after watering. Then pick up a handful and wring it out. What you want is one drop of water. That is the optimum. If you get no water, you probably want a little more. If you get a flood of water you are overdoing the water. Now on to sheet mulching.
Sheet Mulch Steps (Long)
So this year I’m going to implement sheet mulching or lasagna gardening. I go over the detailed steps here and I have an abbreviated list near the bottom of this article.
Cut, Loosen, and Moisten
First, cut down any tall weeds or grasses and do any fine leveling that is needed. If your soil is compacted break it up a little with a pitch fork, but don’t turn or till the soil as this does more damage to the soil life than it does good by loosening the soil. Then give the soil a good watering, as soil life likes a moist, but not soaked environment.
The next step of sheet mulching or lasagna gardening is to do a soil test and see if you need to add any amendments. You may need nitrogen or lime or a number of other additives that would be discovered in a soil test. In my case, I need to add gypsum, which is used for clay soil or compacted soil. I found a 30-pound bag of gypsum at Lowes for $6.00. You can use lime if your soil is too acidic or use Elemental sulfur if you need more acidic soil.
I have done three posts on different soil test kits. They can be found here:
Feed the Soil Life
Then feed the existing soil life. This is done by putting down a layer of compost or manure on the ground. The existing soil life will be used to increase the rate of break down of the organic matter that you will be adding. The faster the organic matter breaks down the faster your garden area will be ready to use. After the compost or manure is put down, moisten it by watering.
Kill Those Stubborn Weeds
The next step will help kill out stubborn weed seeds and perennial weeds. You put down ¼ to ½ inch of newspaper or thick cardboard. If using newspaper, use only the print pages and not the glossy color inserts. Those likely contain a lot of metals and toxins. If using cardboard, remove any stapes, tape, and labels that will not break down quickly. The newspaper and cardboard will break down eventually, but will kill the weeds and perennial plants before it does. It also makes for good worm food as they start working their ways up. Overlap the paper or cardboard by at least 6 inches so weeds don’t come up in the seams. Then thoroughly water this level. I use cardboard boxes folded flat and water the inside, and outside of the boxes before I lay them down and then I water them again while they are down.
Lure the worms up from lower layers by adding manure or compost on top of the cardboard or newspaper and then water it. This will give the worms a reason to work their way up through the layer below.
Thick Layers of Organic Matter
Now add thick layers of organic matter. You want to add 8 to 12-inches. I’m using hay and oak leaves for my carbon layer and then horse manure for my nitrogen layer. You want to watch your carbon to nitrogen layers here and have them be as close as possible to a good compost mixture. Follow the highlighted link for information on compost mixtures. After every couple of layers, add some water to keep it moist. You don’t really want to wait until the end and water from the top because it is very difficult to get the pile evenly wet once it gets thick. The compost link above gives you the full list of what a carbon is and what a nitrogen is.
Quote from Permaculture Magazine
According to Permaculture Magazine: “The first year of break down means the wood (and fungi) steal a lot of the nitrogen out of the surrounding environment, so adding nitrogen during the first year or planting crops that add nitrogen to the soil (like legumes) or planting species with minimal nitrogen requirements is necessary, unless there is plenty of organic material on top of the wood. After the wood absorbs nitrogen to its fill, the wood will start to break down and start to give nitrogen back in the process. In the end you will be left with a beautiful bed of nutrient rich soil”
Now Add Compost
Once the organic matter is added, you want to add some compost on top. If you have some compost that isn’t fully “cooked” yet, that would be even better. The uncooked compost will add composting bacteria to the pile and give it a jump start from the top side on the breakdown process. Even if it is fully cooked, there are still bacteria in there that will help. Now water the compost in.
The Final Touch
Not cap it off. Put a mulch on top to keep the pile moist and so it won’t dry out or blow around in the wind. I plan on using wood chips for my pile. Then water it in. Usually it takes four to six months to break down. If you want or need to plant in the sheet mulch before then, make a hole in the sheet mulch by pushing it aside, add some compost where you need to plant and then plant into the compost.
Sheet Mulch Steps (Short version)
- Level the area
- Cut down any tall weeds or grasses
- Amend the soil as necessary (get a soil test and use the results from that to figure out what you need.)
- Water the area
- If the soil is compacted, break it up a little
- Add an inch or so of manure and then water it.
- Cover with cardboard or ¼ to ½ inch of newspaper, overlap the sheets by 6 inches or so
- Add an inch or so of manure and then water it.
- Add organic material such as straw or wood chips and water again. Try to balance the carbon to nitrogen ratio. See the article about COMPOST
- Put a few inches of compost on top and water in.
- Add a couple of inches of mulch or wood chips to cover the area and water it.
In a few weeks I’ll be posting a video and some pictures of my sheet mulch project out at the farm.