Potentilla Miss Willmot has a height and spread of 35cm, according to the books - however, its growth habit is such that it will sprawl out sideways rather than grow upwards,unless it has plants nearby which it can lean itself against, or grow up through.
Physostegia Rose Queen height and spread 60 cm

if the physostegia is happy she wil reach over 5ft. but a metre is more likely. I had to look up to photograph the flowers [im 5ft3"]