You don't say whether the bed has landscape timbers, stone, etc., around the perimeter, but we assume this to be the case. If the dimensions are 10 x 10 feet or larger, you would have room to use a small garden tiller, but take care around the edges of the material that is used to raise the bed. If it is a much smaller bed or a narrow strip bed, you could easily till it by hand with a sturdy garden fork.
