I hope someone answers this. I haven't grown these, but I got one that I think is Calandrinia umbellata 'Amaranth' in with another plant. After a hail hit the container, I was dunking it a day or two later and broken pieces came off in the tub. A couple of days later I saw them floating (and blooming even) in the water and they had put on roots all along the stems. I ended up with a new container filled with it and they seem to be growing. Yours looks to be a different type, but I'd think you could just whack it off and what is left would put up new growth and the new part could be rooted. Probably a good idea to let it callus over, but I think it might root in either water or soil. I see little pieces growing in the lawn where the hail knocked it off and I haven't done anything to those.
