I have large sempervivum heads that I give a yank and they come out of the soil very easily even though they were pretty established in pots before planted into ground. I noticed that the main root has been eaten out and sometimes the area close to the underside of the head is hollowed out. What could be causing this problem? I don't think I have been overwatering because I have provided much drainage when I prepared the bed for these plants that I have owned for over 5 years.
