Many years ago I bought a dozen ornithogalum - maybe umbellatum? and planted them in an area that I did not disturb. After about 20 years I decided to dig them out and give them to my brother who had just bought 40 acres. Those bulbs had not moved sideways at all, but still formed a dozen distinct clumps. The bulbs went down and down and down, all piled on top of each other. I dug out enough to fill a 5 gallon bucket, and that wasn't all of them. I have been wary ever since. Ten years ago someone gave me a few little bulbs of O. nutans and I put them in a pot. I have just removed them from the pot, to plant in the garden and there are a LOT more bulbs than I started with. Now I am concerned that nutans may prove to be as unacceptably prolific as umbellatum. Advice? Diane Whitehead