I put in a new butterfly garden in the beginning of April this year. I wanted a popcorn cassia as a host plant for my orange-barred sulphurs but couldn't find one. So, I ended up buying a 3' tall by 2' wide scraggly candlestick cassia.
Well, that cassia is now 12' tall X 15' wide and covered in flowers, buds, caterpillars and eggs! I've trimmed several 6-8' lower branches off and several small branches for the enclosure and it just keeps growing! Never seen a shrub/tree that grows as fast!
It's definitely not a plant for a small garden.