I don't know about injuring their roots. I'm sure not an expert on growing them. I've planted lots but only have the 1 living. Late last fall I ordered a bunch on Brent and Becky's sale so I hope they made it through the winter and they come up.
Maybe they're one of those plants like Rancunculus (sp?) that grow like crazy weeds one place and not at all in another.
Yeah, we live off a lake that gets lowered every winter, we live off an inlet that is quite large but only has a trickle of water until April. It's interesting to walk in the dry inlet, and EVERY time we do I kick at the sand/gravel (nothing grows there) and say, "look at this fertile river soil!" and cackle. My DH will never live down his big garden soil purchase (evil laugh)
