You really need to try them again. Lots of water and lots of fertiliser in the summer is the trick.
Right now, 'Bolero' is my pride and joy. I have a 30 year old 'Apple Blossom' I got when I worked in the greenhouses at university. I had to divide it and give most away because it just got to be to big and heavy. The parent it came from was in a clay 60 gallon pot. Back then no one knew how long it was in the collection.