Mine did not really spread at all. I only bought a couple from Hallsons, but I was impressed with the packing and they grew fast after I planted them. (no mail order shock)
They like real good drainage and I did not have them in a good bed for one thing. Also the new cultivars that are tissue culture. They should develope before you let them bloom. I did not do that. That is probably the secret right there is to not let them bloom before the roots develope good.
http://www.portlandmonthlymag....
