What is the longest flowering hardy perennial?
Geranium. Probably one of the longest flowering garden plants, hardy geraniums start flowering around may, and continue to october, depending on the variety. Probably one of the longest flowering garden plants, hardy geraniums start flowering around may, and continue to october, depending on the variety. One of the longest flowering varieties is geranium ‘johnson’s blue’ (illustrated) which is also attractive to bees.