Northspruce......

When I was searching the forum for something else, I came upon an old post from crazy_gardener saying Pudge grew semps. I didn't read the post, as it has 29 follow-ups, but if you'd like to, maybe it'll answer your question =:)

It's titled "Any Semp Lovers Out There?"

Yes, I grow semps :)

They will choke themselves in the center if not divided occasionally. My large patches have much dieback this year because I've neglected dividing which should have been done 2 years ago. If they're a quick growing/spreading variety then I'd suggest every 3 years.

Thanks Pudge, I think they are starting to die back in the centres. There used to be some really big ones and now there aren't.

If those big ones bloomed then that rosette will die after blooming.