My plan for the new garden beds has worked so far. Last fall I filled up two new beds with heaping piles of the last lawn mowing of the season. It was mixture of crunched up leaves and grass. Over the Winter the heaping pile composted down to well below the top level of the bed. This allows for the second step of the plan which is to fill up the bed with top soil. It will be a good eight inches of top soil on top of the composting leaving and grass. It should be good for what ever grows there. This bed I'm working on will be onions and bell pepper plants. It's just a smidge to early for the peppers.