My friend Ben first told me about this technique. To prepare a bed that’s overgrown with weeds, first sheet mulch it with cardboard or paper. I’ve tried both and have had great success, cardboard being able to successfully kill off bermuda grass and dandelions prior to planting. The process is simple: hoe the bed and lay down cardboard or paper in a thick layer. Cardboard takes longer to decompose but works better at killing weeds. It also attracts far more worms. My current preference is brown builder’s paper as our beds are now in good shape and I want to plant right away. After laying the paper or cardboard, soak it thoroughly.
After soaking, cover in topsoil/compost and water it again.
If weed activity was bad, cardboard is better. I found it takes a good month for the cardboard to break down. When it does, however, the soil beneath has a ton of worm activity and really good moisture. If the bed was in good shape and weeds/grass were barely sprouting, paper is enough. When using paper, I plant right away, cutting holes through the paper when the plants go in. In this bed I’ve also buried two watering jugs for watering (see post on watering jugs).
This bed is planted with white kohlrabi and iceberg lettuce.
So far this technique has yielded really good results for a couple seasons.