Knautia macedonica - flowers virtually with all summer with little deadheading.
Euphorbia - green most of time - tiny yellow flowers annually
Must plants in the front garden! Red valerian adds a pop of hot pink to any garden. It's easy to grow and is loved by several butterflies, hummingbird hawkmoths and some bumblebees
Buy Geranium 'Mavis Simpson' from Sarah Raven: An excellent semi-evergreen perennial geranium with soft grey-green leaves and long stems of lovely clear pink flowers.