I try to keep the cost as low as possible. I used 13 bags of each Earthgro Topsoil and Earthgro Humus & Manure mix to fill the bed. I mixed it well so there wouldn't be any hotspots. Should I add anything else to the soil before I start adding my plants? Also, do I need to use a fertilizer? Would worms survive if I found some and tossed them in the garden bed or do they need an extra food source? Thanks so much for the help!