I think the trick with the Bergenia is to remove the outside, ratty leaves like you do with Hellebores. Well that's what I did this year and they're flowering their socks off.
I've since learned that Nerines are like Agapanthus, they like to be crowded. I'm suspecting a bit of coincidence was at work!
Just read up about your Frilly Teries (never grown 'em) and they are also in the Lily family and bulbous so I would seriously try stuffing them into a pot as close as you like and see what they do next year.
You're only wasting the space of a pot behind the shed that way.
...then chuck 'em if they do nowt