The layering technique is my favorite way of filling new or replenishing already established raised beds. Layering (also called Lasagna Gardening) doesn’t require tilling the soil which can disturb the lives of beneficial microbes and soil dwelling organisms. It also doesn’t destroy the soil structure (assuming you have something better than clay or sand!) Often weed seeds can lurk inside the soil and when they get tilled are brought to the surface and then they germinate. Layering actually smothers potential weeds even deeper. I’m sure you can see the benefits of layering and why I like it so much.
Here’s where my raised bed started. It was a mess. Onions on the right were crowded over by weeds. I’ve been leaving grass clippings to dry out on the left side. I use grass clippings a lot to add organic content to the soil and as a mulch.
Then I added more grass clippings – fresh grass from my fertilizer, pesticide and chemical free lawn. That’s extremely important since chemicals will effect the vegetable plants in the raised bed garden.
Next I covered with the Dupont Weed fabric. It’s much easier to lay then newspaper which is what I usually use for this step. Since it is supposed to be biodegradable, is made from wood, and is organic I thought it would work fine for this step. I had to hold it down on one end with a brick to keep it in place while I covered it with soil.
Next I covered with a soil mix of compost, bagged topsoil, and soil conditioner. The soil will keep the weed fabric down which should prevent weed seeds from germinating underneath. We’ll see how well it works this year.
Here is the filled bed. Nutrients from the top layers will seep into the soil underneath and enrich the bed.
10 Bags of soil, 4 bags of soil conditioner, a wheelbarrow of compost, and several bags of grass clippings filled three raised beds (3’x10′, 4’x10′, and 84″x42″). I don’t shy away from using weeds (without seeds) as bottom layers as long as I remove the roots or let them sufficiently roast under the sun.
I didn’t include the following list in my post Designing a Raised Bed Vegetable Garden: 11 Things to Think About but probably should have!
Good materials for layering a raised bed:
Newspapers, cardboard, tree leaves (in fall) – leaf mold, grass clippings, kitchen scraps (avoid animal products), straw, manure (often best to let it fully compost before use).