Re: new garden by smothering
Most books will recommend waiting, but in my experience this is not always necessary. It probably depends what you are planning to plant in the new bed as to whether you will want to plant right away or wait until the grass is really dead. Maybe I am impatient, but I usually use this method without waiting. For instance I just planted a 100′ hedge of willows using this method. The willows were cuttings, so I laid down newspaper and soil/sweet peat mix that I had left over from another project, cut a hole through the newspaper and slipped them in. Last year I grew my sweet potatoes in a new bed on the lawn. I placed cardboard on the grass were I wanted the bed and then put a 12″ deep wooden raised bed on top, filled it with sandy soil and immediately planted the sweet potatoes. Two years ago, I grew my pumpkins on smothered grass; I put down cardboard and then a very thick landscape fabric down directly on the grass, cut an x for each seed and planted. Things might grow a little better if you wait, but as I said I’m impatient and next year the bed will already be made! There are some things that would probably be a pain or wouldn’t work if you didn’t wait such as small vegetable seeds (carrots, lettuce, radishes) or a lot of perennials that you intended to cut holes through the cardboard/newspaper to plant. The more holes you cut, the more light gets to the grass and the harder it struggles to survive; pieces often find their way through the holes and need to be weeded out. The only time when I wait to plant is when I am making a new bed in the fall and I wait till spring!