A common question that arises in raised bed gardening is what to do when you have a bed completely overgrown with weeds and grasses. Josh Singer, the urban garden specialist with DC Parks and Recreation, recommends sheet mulching the bed. Sheet mulching is great because it kills the weeds and grasses and improves the soil, while using just recycled and natural materials. We put this permaculture technique into practice on Saturday at Engine 26. I was aided by a new firefighter at the station named Henry, and Everybody Grows volunteers Joel and Liat.
Henry and I started by cutting down the tops weeds and grasses.
We cut back most of the weeds, particularly where they had gone to seed. Next we added layers of cardboard. Most shipping cardboard biodegrades safely. It also forms a sturdy weed block.
We stacked the multiple layers cardboard so the overlapped to cover gaps, and we cut back the weeds that protruded from the sides. After the cardboard, it was time for a layer of compost. We used Leafgro compost. Joel and Henry poured the compost directly on top of the cardboard.
The last layer we applied was mulch. I got a good deal on some Earthgro Red Mulch, which is what we used here. Even though it has coloring to make it red, it is a wood mulch and safe to use in a vegetable garden. I expect it to work well.
By getting an early start on this process for next year, I am intentionally leaving plenty of time to adjust it or supplement it. I will report back on our sheet mulching experiment in future blogs, so stay tuned!