How long have you had it? Two 'Breden Spring' (or whatever it's called) didn't seem to grow at all for 3 seasons. Doing better this year, but not nearly as big as they should be. Can't explain it; maybe they can't compete with their neighbors - coneflowers and Russian sage. Have lavatera in other locations growing like crazy - even in mostly shade. Don't have 'Red Rum' but have couple other kinds. They are in places where they have lots of room to do their thing.

Lavatera are such short lived stars that they need to be tucked in the bushes.

Likely these are apt to fizzle sooner if soil and exposure not the best for them. I did have a planting of this or a similar dark one deteriorate a little sooner than might have been expected, after growing pretty well for at least a few years. But as stated none are long-lived anyway, so it was probably really a matter of something like two good years vs. maybe three or four at best.

I went to the nursery where I bought this and talked to one of the gardeners. It does bloom and finish earlier than some other varieties. My space is limited so I'm replacing it with a 'Blushing Bride' hibiscus. It'll give me the size I want and won't look ratty at this time of year.