A well-designed garden provides interest from early spring through late autumn, and beyond if you also select plants for winter structure. But, for the main growing season, much of that interest comes from flowering and foliage plants. Gardeners who want a lower maintenance landscape would be wise to look for perennial plants that are both easy-to-grow and offer a long blooming period. Most perennial plants flower for two to four weeks, but the longest flowering perennials, like coneflowers and catmint, measure their flowering period in months, not weeks.
The Longest Flowering Perennials
When planning a garden with long-blooming perennials, the same basic rules of design apply; choose a mixture of early, mid-season, and late-flowering plants. Of course, you can also affect both the bloom time and length of the flowering period with pruning practices; pinching, deadheading, and shearing. Read on to discover how to encourage months of blooms by combining clever pruning with the longest flowering perennials.
The Early Bloomers
Catmints ‘Sylvester Blue’ & ‘Little Trudy’ (Nepeta, zones 4 to 9). These compact plants bloom their heads off from late spring until mid-autumn with a heavy show of purple-blue flower spikes that are extremely attractive to pollinators and beneficial insects. Once the initial flush of flowers begins to fade, give the plant a haircut, shearing it back by about one-half. Without a trim, the plant will continue to flower moderately, but a good shearing encourages tidy foliage and plenty of blooms that will persist until frost.
Salvia ‘Marvel Blue’ (Salvia nemerosa ‘Marvel Blue & Rose’, zones 4 to 9). The Marvel family has the largest flowers of any Salvia nemorosa on the market. Enjoy the stunning display of color in Spring and Summer. Little to no maintenance required in the garden. This hardy plant forms 14 to 16-inch-tall mounds of spreading foliage, which is topped with bright violet-blue or rose flowers with attract hummingbirds, butterflies and other pollinators. After its initial bloom, the plants will continue to pump out a moderate number of fresh flowers for months. However, if you shear the plants back by one-third after the first blossoms fade, you’ll encourage another heavy show of flowers.
Penstemon ‘Coral Baby’ (Penstemon barbatus ‘Coral Baby’, zones 5 to 8). It is relatively compact, growing about 15 inches high and 12 inches wide. The bright green foliage is handsome and sets off the intensely saturated color of the flowers that appear from late May into July, longer when dead-headed. It is long lived for a Penstemon, and is undemanding if planted in full sun and well-drained soil. In addition to just looking lovely, the tubular flowers of Coral Baby will attract bees, butterflies, hummingbirds and hawk moths to your garden.
Pruning Tip – Don’t be afraid to grab those pruning shears once that initial bloom of spring flowers starts to wind down. Many perennials will continue to produce flowers all season, but in a lesser quantity. If you want a heavier bloom, shear the plants back by one-third to one-half to push out fresh foliage and flowers.
The Mid-Season Superstars
Everblooming Daylily ‘Stella de Oro’ (Hemerocallis ‘Stella de Oro’, zones 3 to 9). ‘Stella de Oro’ features profuse 2.75-inch diameter yellow flowers with ruffled edges and deeper yellow throats. Flower is classified as a miniature. Flowers are borne on naked stems (scapes) above a clump of arching, linear, blade-like leaves. Individual flowers open for one day. This multiple AHS award winner has become perhaps the most popular daylily in cultivation in large part because of its compact size, vigorous growth, profuse bloom and extremely long bloom period.
Coneflower ‘Sombrero’ & ‘Kismet’ (Echinacea purpurea, zones 3 to 9). Coneflowers are the cornerstone of a summer perennial garden, blooming for months, even in dry, hot conditions, and providing food for butterflies, bees, and other pollinators. There are countless cultivars available to gardeners, but for months of flowers, it’s hard to beat selections like ‘Sombrero’ for tall and ‘Kismet’ for short. Both flower from early summer into mid-autumn, especially when deadheaded regularly.
Yarrow (Achillea millefolium, zones 3 to 9). A butterfly favorite, yarrow is a robust summer bloomer with pretty, flat-topped flowers that bloom for 6 to 8 weeks. The ferny foliage emerges in early spring and is followed by the two to four-foot tall flower stems in early summer. Yarrow is one of the longest flowering perennials that grows best in full sun with well-drained soil of average fertility; over-fertilizing can cause the stems to flop over. Flower colors can range from soft pastels to rich jewel shades. Deadhead spent flowers by clipping the flower stem back to the main foliage. Top varieties include ‘Moonshine’, which has pale, yellow flowers and ‘Desert Eve Red and Deep Rose’ with red and rose flowers
Pruning Tip – As summer flowers fade, deadhead often, cutting down to a fresh stem or set of leaves. This will push the plants to continue producing more blooms. Small flowered perennials, like ‘Moonbeam’ Coreopsis, can be quickly and easily deadheaded with hedge shears, rather than snipping individual blooms. In late summer, as flowering winds down, stop deadheading to allow some blooms to go to seed. Seed heads provide valuable food for birds and add interest to the winter garden.
Fantastic Fall Flowers
Black-eyed Susan ‘Goldsturm’ (Rudbeckia fulgida ‘Goldsturm’, zones 3 to 9). ‘Goldstrum’ lights up the late summer garden with weeks and weeks of bold color that persists into September. Each coneflower-shaped flower has a raised chocolate-brown center cone that is surrounded by golden petals. The drought-tolerant plants grow about two-feet tall and offer the best visual effect when planted en masse. Deadhead faded flowers to prolong the bloom period.
Fall Switch Grass (Panicum virgatum ‘Shenandoah’, zones 5 to 9). By late summer, many cultivars of Switch grass produce soft, feathery plumes that emerge above the narrow foliage. Fall Switch Grass is a medium-sized Switchgrass grass, growing three to four-feet tall with foliage that turns from bright green to fiery reddish-orange in early autumn. The attractive plumes are reddish-pink and persist on the plants throughout winter. Plant it in a sunny site with well-drained soil. Pruning is only necessary in early spring when the dried foliage and flower stems from the previous season are cut back before the fresh growth emerges.
Pruning Tip – In late spring, pinch out the tips of late summer and fall blooming perennials like sneezeweed, Joe Pye weed, Russian sage, and Sedum ‘Autumn Joy’. Pinching will slow flowering and produce bushier growth, which means more flower-bearing stems.