What is the longest flowering summer plant?
Geranium. 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. Butterfly bush have one of the longest bloom times of all garden plants: they seem to never be without flowers from early summer through autumn. This makes them perhaps better called “continuous bloomers” over rebloomers, since they don’t really take a break like other plants on this list do.