Hi Jim - Crinum americanum spreads quite prolifically in ideal conditions quickly forming healthy patches. I keep a couple selections of this species in 7-10 gallon nursery containers lined with plastic and filled with sandy soil mixes and submerged to the rim in a garden pond. I fertilize the with slow release pelletized fertilizer made for pond plants and trees. Under these conditions if I don't reduce or divide the plants every 2-3 years, the plants themselves with rupture the pots. Care also must be take to make sure the stolons don't eventually make their way out drain holes. I have not had much luck growing true native C. americanum in soils that were not extremely moist or at least occasionally saturated. They will sometimes persist but don't bloom well or at all. I have had several people insist this is not true of all C. americanum, but I have never had other experience. C. erubescens and other American Crinum forms grow happily in garden soils that more typically wet, but still prefer moister conditions. I use this to help contain the spread of C. erubescens which I have planted in a naturally moist spot that is dryer in around it. This patch so far is 12-15 feet across depending on which way it is measured. Basically if these plants are happy, they seem to spread quite happily -- Alani Davis