That is not my experience here with Cedar Sage. They usually bloom for a fairly extended time in the spring, occasionally in summer (depending on heat, I guess) and some blooms can occur in fall also. But then, too, I have numerous Cedar Sage plants, so I suppose if I only had one, the blooms would certainly be less. Cleistogamy has to do with plants being able to form seeds from a form of closed blooms even if extreme heat keeps them from making more visible flowers, I believe.
