Green Thumbs Up: Late-blooming beauties for sun and shade

Suzanne Mahler

As the fall season progresses, even the most meticulously maintained perennial borders tend to lose their overall, tidy appearance. Many plants seem to flop and sprawl as they don their varied autumn tints. My eloquent friend and garden writer Sydney Eddison likens the appearance of the fall perennial garden to a “proper lady removing her girdle,” a portrait that ideally describes the transition of our gardens during the fall season. Even the most stalwart, upright plants are inclined to relax as they prepare for their winter’s nap after a long season of colorful splendor.

Despite the noticeable decline of flowers and foliage during October, my landscape still offers splashes of welcome color. Spectacular sky blue morning glories greet me at dawn’s early light, their tender tendrils twining along my deck railing. As the day progresses and their fragile flowers fade, the massive blooms of glistening white moon flowers unfurl, lingering into the evening hours. Broad patches of lantana boast a bounty of red, yellow, pink, and lavender blossoms above deep green, mint-scented foliage, attracting bees and butterflies during the warmth of the day.

While the prolific blooms of many September-blooming asters have faded, the statuesque Aster Tataricus is just beginning to display its lovely clusters of lavender-blue daisies highlighted by yellow centers on 6-foot-tall stems. This Siberian native is a vigorous grower, but I find it easy to eradicate when it wanders and consider its exuberance a small price to pay for its fabulous architectural presence and blooms through the latter half of October into November. It offers a lovely complement to the lingering bright yellow daisies of the stately, Rudbeckia nitida "Herbstsonne" that has been in bloom since mid-July and to the new flush of bright pink blossoms on a Bonica rose.

I tend to avoid most rampant spreading perennials, but with relatively few season extenders to brighten the fall landscape, I make some exceptions. Some of these have been relegated to a garden that borders my wetlands meadow where their aggressive habit and coarse appearance offer a transition from Mother Nature’s wild garden to the slightly more manicured and structured gardens in my front yard. Perhaps the showiest display this month is offered by a large expanse of a hardy member of the Joe-Pye-Weed family known as perennial ageratum (Eupatorium coelestinum). Although it has a tendency to spread rather rapidly when grown in the moist soils it prefers, the fabulous display of showy lavender-blue blossoms during the fall season is worth annual thinning, plus it serves as an irresistible lure to multitudes of bees and butterflies. Companion plants include clumps of daylilies, tall phlox, Echinacea and black-eyed Susans, which all seem to happily coexist while providing multi-season color in this low maintenance bed.

Daisies are the mainstay of most perennial borders offering a wealth of long-blooming annuals and perennials in diversity of colors, many proving late season color. While traditional chrysanthemums are best known for their fabulous fall color, I favor the bountiful flowers of the Korean chrysanthemums (Dendranthema grandiflorum) which are just now coming into bloom. These vigorous, hardy perennials, commonly known as Sheffield daisies, bear a multitude of pale pink, peach, or white flowers throughout the late fall but are often difficult to find in the trade. They are readily transplanted by the shovelful at any time during the growing season if you know a gardener willing to share. In recent years, it seems more South Shore gardeners have discovered the carefree October-flowering Montauk or Nippon daisies (Nipponeanthemum). Showy clumps produce 2 1/2-inch blooms reminiscent of earlier-blooming shasta daisies, set against glossy, dark green, leathery leaves. Adaptable to nearly all well-drained soils, woody stems should be sheared in spring to promote compact growth and more fall blooms.

My shade gardens boast several late-blooming treasures. While many of the hostas have tattered foliage and have lost their luster, Persicaria "painter’s palette" is a perpetual bright spot from early summer through the fall season, always prompting inquiries from my garden visitors. While some might consider this moisture-loving perennial a nuisance due to its propensity to seed prolifically, it offers spectacular cream, green, pink, and red leaves throughout the growing season and during the latter half of September through October, thin thread-like spikes appear at the tips of the stems bearing tiny bright red flowers resembling little beads. I often share seedlings with visitors and while I send it along with a warning label, the tropical-like foliage is irresistible, plus offspring are easily extricated or transplanted.

Members of the bugbane family (currently classified as Actaea; formerly Cimicifuga) are another shade-loving perennial that I favor for their handsome, divided foliage with the added bonus of attractive bottle-brush blooms. While most bugbanes bloom in mid to late summer, Cimicifuga simplex "white pearl" waits until October to displays its lovely wand-like flowers. In recent years, a native late-blooming wood aster (A. cordifolia) has naturalized alongside white pearl providing dense clusters of pale blue flowers.

The Azure Monkshood (Aconitum carmichaelii) is a stunning addition to the October landscape. Stems 3 to 6 feet tall produce elegant glossy foliage reminiscent of delphiniums and bear spikes of large hooded bluish-purple flowers. These handsome, hardy perennials perform best when grown in moisture retentive soils in sun to light shade. For those who love delphiniums but struggle to keep them alive from year to year, consider growing this and other members of the monkshood family.

As the growing season draws to a close, it may be difficult to procure these late-season treasures, but now is a great time to begin next year’s wish list for these terrific season extenders.

Suzanne Mahler is an avid gardener, photographer and lecturer who has been developing the 1.5-acre property surrounding her home in Hanover, Mass., for more than 30 years. She is a member of two local garden clubs, past President of the New England Daylily Society, an overseer for the Massachusetts Horticultural Society and is employed at two garden centers.