My dorisiana (East Bay) has approached the five foot mark in the past but is currently cruising at four feet. It really appreciates some regular watering and certainly is at its best in Jan/Feb/March.

Here is a link that might be useful: dorisiana

I'm in SoCal, but our summers are hot and dry also. I have s.dorisiana growing in quite a bit of shade and it's about 5' tall and flowering. It's against a fence beneath a 'laced' pine tree. I'll soon try it also in a spot with a bit more sun to see if it's more floriferous there.