If you have ever made or eaten lasagna, you know it is constructed in layers. A "lasagna garden" is much the same. It is a garden using layers of various organic materials. Also known as "sheet composting," this labor-saving gardening technique creates a compost bed quickly and is useful for planting either vegetables or flowers.
Some of the advantages to this approach are:
- Requires no digging or tilling, saving labor and time.
- Is economical and easy on the budget.
- Is environmentally friendly; no chemicals are used.
- Reduces weeding, water consumption and soil erosion.
- Makes for easy composting since no turning of the pile is necessary.
- Improves soil structure.
- Builds a robust earthworm population in your soil.
Here’s how it works.
After selecting a site, simply spread 10-15 layers of overlapped newspaper (no glossy paper) or wet cardboard as the base. When you properly layer the cardboard you don’t have to remove the sod underneath or worry about weeds because the cardboard will smother them and this organic matter will eventually compost itself. This procedure eliminates the need for any herbicides. Just make sure to not leave any gaps in the cardboard pieces where the sod can grow through.
Next, add a layer of woody material such as small branches or twigs. Follow this by alternating layers of organics such as peat moss, grass clippings, shredded leaves, manures, straw or hay. Any compost or good topsoil also will make an excellent layer. Food and vegetable scraps (other than dairy, meat or fats) can be added to the bed. Then, all of these compost layers will eventually rot in place.
Each layer should be 4-6 inches deep and watered well before the next layer is added. There is no set formula for materials to use or order of materials, except several layers of paper should be on the very bottom. A typical height for the finished bed is 18-24 inches.
It is best to alternate brown materials that are rich in carbon (peat moss, paper, sawdust, woody material, shredded leaves, etc.) with green materials that are rich in nitrogen (grass clippings, vegetable scraps, yard trimmings, manures). These green materials contain the needed nitrogen to breakdown the brown organics.
Building a fall lasagna garden, which is to be planted in the spring, is ideal. The material will have had time to decay or "cook." This reduces the overall volume and releases rich nutrients into the soil, thus making it ready for the next growing season.
However, if you wish, you can assemble your lasagna garden in the spring and seed or plant immediately after construction. Just be sure the top layer has 4-5 inches of finished compost or soil. You can plant or seed directly into the compost/soil.
As time goes on, continue to add layers of organics. It will break down into a rich garden soil that will serve you and your plants well for years to come.
Thank you to Tulsa County Master Gardeners for their expertise in this subject matter. Allen Robinson has been a Master Gardener since 2010.