While many of the hardiest, longest-lived perennials flower for only 2 to 3 weeks at a time, there are some that bloom all summer. To maximise the potential of a perennial bed, choose long-blooming plants that are well-suited to the local climate, and remove spent blossoms on a regular basis to prolong bloom time and encourage flower production.
Tall, lanky perennials such as yarrow, coreopsis, blanket flower and golden marguerite are some of the longest-blooming perennials in the garden, flowering from early summer until fall. These low-maintenance, easy-to-grow plants are the mainstay of many gardens, filling the yard with bright splashes of colour for months on end. Individual flowers may last only a few days, but the stems are capable of producing multiple blossoms if the blooms are removed as they begin to fade. When the growing season comes to an end, trim the leggy stalks by cutting them as close to the base of the plant as possible; this will result in the growth of a denser, sturdier plant.
Thick, bushy perennials such as baby's breath, Russian sage and bee balm make invaluable fillers between groups of flowers in formal arrangements. Though these plants are often as wide as they are tall, they bloom up to 12 weeks at a time, producing an abundance of blossoms that decorate the stems and soften the shrublike effect. To increase the flowering potential of these plants, remove faded flowers with pruning shears or hedge trimmers; this is more efficient than trying to remove the tiny blossoms by hand.
Ground-hugging perennials such as garden pinks, stonecrop and candy tuft blanket the yard in dense mats of thick foliage and eye-catching flowers for 8 to 12 weeks at a time, and bloom time can be extended by cutting back individual clusters of flowers as they begin to fade. While these perennials make excellent ground covers, their gently rounded forms and delicate blooms also work well when added to borders and beds, where they contrast nicely with more-vivid flowers and foliage.
Many annuals bloom nonstop from early spring until the first frost of fall, putting nearby perennials to shame with their prolific blooms. On the down side, they must be replanted each year and they tend to require more routine maintenance throughout the growing season, making them less convenient than perennials. There are, however, a number of hardy, easy-to-grow annuals that will readily reseed in the garden. Self-sowing annuals such as sweet alyssum, cosmos, poppies and larkspur fill the yard with colour all summer and reappear each spring without replanting, just like perennials. In addition, they tend to be tolerant of a wide variety of climatic conditions and will flourish in spaces where many plants fail.