Perennials provide a long sequence of bloom if plants are carefully selected. Very early bloom can be obtained by planting spring flowering bulbs with perennials. The peak perennial bloom comes in June and July with a scattering of bloom ending with the chrysanthemums in the fall.
Once planted, perennials come up every year for a number of years. Unfortunately, some don't last very many years. The life span of a particular planting of perennials depends on the soil type and the care the bed receives.