I have one of those 2' or 2-1/2' diameter whiskey barrels with the plastic insert that's about a foot deep and used for plantings. Up to this point it's only been collecting water when it rains and it's about time I get the thing set up with flowers of some kind. Can anyone help me with what should be the various layers that I should be putting in the barrel. Choice of flowers? If I load it with top soil for planting, will everything get waterlogged when it rains? There are no drainage holes in the plastic insert. Should I be putting a few small holes in it? Any advice would be greatly appreciated.

Started a dracaena fragrans by taking a cutting from a mature plant. http://www.hear.org/starr/hiplants/images/600max/html/starr_060826_8674_dracaena_fragrans.htm My new plant was approx. 6" in length (2 months ago) and is growing well (10") now. My question is how extensive of a root system does this plant have? How big a pot should my plant be planted in? When I started the cutting, I simply placed the cutting in a small pot 4" and now am thinking it should be in something larger however, I have no idea what type of root system this plant has. thank you!