A Look under the Layers of Lasagna Gardening

By Sarah Densmore

If you don’t dig digging and if the thought of amending the Constitution seems easier than amending your plant beds, lasagna gardening might be for you. When you lasagna garden, you don’t dig up existing grass or till spent turf. You simply outline your plot and lay down layers of the same nitrogen- and carbon-rich ingredients you’d normally add to a compost heap. (Another name for lasagna gardening is sheet composting.)

Unlike traditional composting, you don’t have to periodically aerate your lasagna or keep an eye on its moisture level. Just let the layers lie there and bake into the earth. In a few months your soil will be rich and ready for planting.

Before you begin applying your layers, remember that your aim is to incorporate nitrogen and carbon, two elements that together produce the energy and organisms essential for soil and plant health. Basically, the ingredients you’ll use for each layer are either nitrogen rich or carbon rich. Generally, you’ll want a carbon to nitrogen ratio of 2 to 1. So for every 2 inches of carbon material you put down, lay on 1 inch of nitrogen material.

Your nitrogen layers will be the green or food-based stuff, such as grass clippings or other green plant material, leftover fruits and vegetables, coffee grounds, egg shells, and animal manure. Steer clear of animal meats and any type of fats.

Ask your local grocery stores and restaurants if they’ll give you the fruits and vegetables they intend to throw out. Local coffee shops might be willing to give you their used grounds.

Your carbon tiers will be the dry, dead stuff, including dry leaves, straw, hay, newspapers, and very small twigs and wood chips. Your material should be free of seeds so unwanted plants don’t sprout up.

Garden lasagna is a lot like dinner-time lasagna. You can customize the ingredients to suit your taste. Just make sure your recipe has a mix of nitrogen and carbon. Now that you’ve got a list of possible ingredients, here’s how to assemble your plot of lasagna:

Put down 6 to 10 sheets of newspaper or one thickness of corrugated cardboard so that it completely covers the area you want to plant.

Overlap the edges by 4 or 5 inches. Completely soak the paper or cardboard with water to set it in place. This will ensure that no light gets in, signaling the end of and whatever grass or other plant material lies underneath. If you use newspaper, don’t use the full-color, glossy ad pages. The inks may be harmful to the environment.
Add in a 2- to 3-inch thick layer of nitrogen material.

Doggie and kitty poop doesn’t belong in your lasagna. In fact, it could contain organisms harmful to your garden. Planting manure is excrement created by poultry or by plant-eating livestock such as cows or pigs. If you don’t live on or near a farm, your local hardware store probably sells bags of composted manure.
Next apply 4 to 6 inches of carbon-rich items. Your lasagna will cook a lot faster if you chop up your leaves, twigs, wood, etc. into very small pieces and shred your newspaper.
Add another layer each of nitrogen and then carbon ingredients.

When you’re done, your layers will be 1- to 2-feet tall, but the mound will shrink as the materials break down and are absorbed by the soil.

Consider placing plastic over your newly made bed of lasagna for the first two weeks. This will help protect the top layers from the wind and provide some extra heat to kick start the decomposition process.

In a few months, your soil should be well fed, crawling with aerating earth worms, and ready to receive your plants, bulbs, and seeds. If you used cardboard as your base, you may find it hasn’t completely broken down yet. That’s okay. Just cut through it.

You can assemble a lasagna garden at any time of year as long as you can get the necessary ingredients. Most people in colder climates build their layers in the fall in preparation for spring planting. Autumn also allows them 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.