Just when the colors of summer flowers are fading, late-blooming perennials are ready to take center stage. In addition to the usual fare of coneflowers, mums and ornamental grasses, many lesser-known characters are ready to perform.
Agastache foeniculum, also known as Blue Giant Hyssop, packs 4-5 inch long dense spikes of bright blue flowers on 3 foot tall, upright plants. Butterflies and hummingbirds love this plant, as do bees.
Japanese Anemone (Anemone x hybrida) offers 2-3 inch blooms in various shades of pink or white atop a 2-4 foot mound of foliage. Anemone performs best in morning sun/afternoon shade with rich, moist soil. Grapeleaf Anemone (A. vitifolia) also blooms in early fall and is a bit more stress tolerant.
There are several Asters that bloom in the fall, most notable being Aster x frikartii, featuring lavender blue, daisy-like blooms with yellow centers on 3-foot stems. The Michaelmas Daisy (A. novi-belgii), is taller and has a more violet-purple bloom, though there are white-, red- and pink-blooming and compact cultivars available.
Butterfly Bush (Buddleia davidii) is a woody shrub, but in our area it is best maintained as if it were an herbaceous perennial, meaning to remove all of the above-ground foliage in winter. If left from year to year, the wood tends to be open and weak. But, since it flowers on current season’s growth, forcing new stems to develop each spring will still result in blooms in late summer and early fall. Butterfly bush is lavender to purple in color, but many selections are available in white, pink and even yellow.
Bluebeard (Caryopteris x clandonensis) should also be treated as if an herbaceous perennial by cutting it to the ground each winter. The lovely, blue flowers are accompanied by grey-green fragrant foliage and, though it flowers best in full sun, will perform reasonably well even in part shade.
The bugbanes sound a bit better when called by their botanical name of Cimicifuga. C. ramosa flowers in early fall with fragrant white to pinkish-white blooms on bronze to blackish-purple foliage. Closely related Kamchatka bugbane (C. simplex) bears white bottle-brush type flower spikes on arching sprigs of green foliage. Both species are sure to chase away your end-of-summer blues. The bugbanes prefer cool, moist locations and should be sited with afternoon shade.
Joe-Pye Weed (Eupatorium purpureum) commands attention with 5-7-foot tall plants crowned by huge clusters of fine-textured purple blooms. Closely related E. maculatum has purple mottling on the stems.
There are many species and cultivars of Sedum that strut their stuff in late summer, ‘Autumn Joy’ being the most widely planted for its pink flower buds that burst into a rosy red spray of color.
Goldenrod (Solidago hybrids) has many fine selections ranging from 1.5-6 feet in height. The various shades of clear to golden-yellow blooms provide excellent contrast to the many blue-flowered fall species. Goldenrod has gotten a bad rap for aggravating hay fever allergies, but, in fact, their pollen is heavy and sticky and not likely to be airborne. Ragweed also happens to be in bloom at about the same time and is far more likely to be the culprit.