Unusual fall perennials

Fall is a wonderful time in the garden. The cool, crisp air encourages plants toward dormancy; perennial foliage starts to yellow and wither as deciduous trees paint the landscape with a kalei doscope of colors. As we reluctantly accept the inevitable and begin preparing our gardens for winter, we can ease the transition by planting selections that provide color and excitement at this time of year. While many gardeners have traditionally turned to mums (Chrysanthemum spp. and cvs., Zones 5–9), goldenrods (Solidago spp. and cvs., Zones 3–9), and sedums (Hylotelephium spp. and cvs., Zones 3–9) to extend the gardening season, many also long for something different. Luckily, there are many unusual, lesser-known perennials that offer gardeners exciting opportunities to create dynamic, late-season displays.

SPECTACULAR PICKS FOR SUN Alliums typically make wonderful contributions to mixed spring and summer beds and borders. Stunning globes in shades of pink, purple, and white sit atop stems ranging from a diminutive 8 inches to a towering 4 feet in height. ‘Ozawa’ allium, which starts to bloom in September, is one of the latestflowering alliums in the genus. Somewhat droopy spheres of luscious, lavender-purple flowers rise above mounds of attractive grasslike foliage. Unlike some alliums, ‘Ozawa’ rarely produces seedlings and is not aggressive. Best suited to free-draining soil, this floriferous bulbous plant blooms for weeks and will be abuzz with happy, hungry bees in the waning light of autumn days.

“Better late than never” could be said about the flowers of monkshood, which usually don’t start blooming in earnest until early to mid-October. ‘Arendsii’ monkshood features 4-foot-tall stems topped with dense panicles of richly saturated cobalt-blue flowers. Place this stately perennial toward the back of the border in rich, consistently moist but not overly wet soil. Sunny sites are fine for cooler regions, as long as the soil is not allowed

‘Arendsii’ monkshood

Aconitum carmichaelii ‘Arendsii’

ZONES: 3–7 SIZE: 2 to 4 feet tall and 1 to 2 feet wide CONDITIONS: Full sun to partial shade; moist, well-drained soil

to dry out, while gardeners in warmer areas should provide dappled shade. If you are like me and usually forget to provide support to tall perennials likely to flop, ‘Arendsii’ will put your mind at ease; its stout stems stand at attention, rarely requiring staking. But be sure to wear gloves while handling this plant, as all parts of it are poisonous.

‘Plum Peachy’ narrow-leaf ironweed sports clusters of vibrant lavender-violet flowers that contrast spectacularly with the warm-colored tones of other plants in fall. As the common name suggests, the foliage is thin and linear; it looks a lot like bluestar (Amsonia spp. and cvs., Zones 5–9) foliage. The leaves add a wonderful contrasting texture when placed ‘Plum Peachy ’ near big, bold-foliaged neighbors. narrow-leaf Although this species is native ironweed to the Southeast, it does well in Vernonia angustifolia ‘Plum Peachy’more northern climates. Here in ZONES: 5–8the Northeast, the graceful clumps SIZE: 3 to 4 feet tall don’t start to flower until October and 2 to 2½ feet wide and continue to bloom for several CONDITIONS: Full sun; weeks or until a killing frost, to the medium to moist, delight of late-flying pollinators. As well-drained soil a bonus, the narrow foliage takes on NATIVE RANGE: Southeastern United a purplish blush toward the middle States of fall, just in time to highlight the violet flowers.

Finding a ground cover that ‘Snow Flurry ’ produces flowers in autumn can heath aster be difficult, but when you succeed Symphyotrichum it’s definitely cause for celebration! ericoides var. prostraDiminutive ‘Snow Flurry’ heath tum ‘Snow Flurry’ aster is a prostrate form of native ZONES: 3–9 SIZE: 3 to 8 inches tall heath aster. Its stiff, arching stems, and 1 to 3 feet wide which are covered in needlelike CONDITIONS: Full sun foliage, look a little like a creeping to partial shade; juniper (Juniperus spp. and cvs., dry to moist, welldrained soilZones 3–9). When ‘Snow Flurry’ NATIVE RANGE: blooms in midfall, the abundance North America of tiny white flowers often entirely conceals the leaves. A lover of sun and well-drained soil, this little powerhouse is the perfect choice for rock gardens or the front of a sunny border. Its unique, creeping habit is especially effective when the stems are allowed to cascade over stone walls or meander between rocks. It looks wonderful planted en masse where it can truly look like a blanket of snow.

Ornamental grasses are structural plants that act as the backbone of garden plantings, frequently adding

Dig up and lift the perennial from the ground.

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Tips on dividing perennials

Dividing perennials is one of the easiest and cheapest ways to get more plants. All of the perennials featured in this article can be divided, but how and when should you do it? Here are some principles and guidelines to keep in mind for best results.

UNDERSTAND THE SCIENCE BEHIND DIVISION Dividing puts a lot of strain on a perennial; by being uprooted and cut into pieces, a plant loses part of its root system. A freshly divided plant needs to conserve water and put energy into creating new roots. If there is already substantial growth on the plant, the root system may be spread too thin to be divided. Trying to maintain a mass of foliage and then being asked to establish new roots might be too much for the plant. If there are a lot of leaves, the plant may also be losing water faster to transpiration than it can replenish with a smaller root system. For these reasons, dividing a perennial in summer when the weather is hot and sunny and the plant already has a lot of growth is a bad idea.

GET THE TIMING RIGHT Spring is the best time to divide a perennial because there is less growth on the plant than later in the growing season and the weather is mild. To ease the stress on the plant, try to time your division to coincide with a stretch of cloudy, rainy weather, and be diligent about watering for several weeks after division. You can also divide perennials in fall (pictured), but you should cut back some of the foliage and any flower stalks to help it conserve energy and water. Don’t divide in late fall, because plants may not have enough time to establish themselves by winter. Perennials that have been divided too late in the season may also be susceptible to frost heaving over winter.

MAKE THE RIGHT CUTS Using a spade or fork, lift the perennial from the ground and shake off some of the soil. This will help you see natural places to split the plant. Make sure each division will have two to three strong growing points and a decent root system before you divide; if these conditions are met, you can divide the plant into as many pieces as you want. Be sure to sterilize whatever tool you use to cut the roots prior to dividing, as well as between different plants, to reduce the chance of spreading disease. Divide the root system, and cut off excess growth and flower stems.

Replant and water.

nearly year-round color and texture to designs. However, it’s in fall when most step up and capture our attention. One of the most impactful native grasses is big bluestem, which can achieve an impressive height. ‘Blackhawks’ big bluestem (photo p. 35) possesses all the great qualities of the species, along with one big bonus: The wide, graceful blades that emerge green in spring gradually shift to purple and finally a dark purple-black as fall progresses. Elegant flowering stems may rise 7 feet tall, topped by three-parted inflorescences that look like turkey plumage. Like all other big bluestems, ‘Blackhawks’ is an adaptable, drought-tolerant plant that performs admirably with little care. Avoid very fertile or amended soil as well as shade; these conditions will cause lodging or flopping. To take full advantage of the dramatic color of ‘Blackhawks’, dot it periodically throughout a garden bed (see “Designing for year-round interest, p. 39), or if space allows, make a statement and plant this exceptional nativar en masse. And for those of us who garden in deer country, Bambi and friends will walk on by. ‘Cheju-Do’ Japanese bugbane

Yellow wax bells Kirengeshoma palmata ZONES: 5–8 SIZE: 3 to 5 feet tall and 2 to 4 feet wide CONDITIONS: Partial to full shade; moist, well-drained soil NATIVE RANGE: Japan, Korea, northeast China

SELECTIONS THAT SHINE IN SHADE

Actaea japonica One plant that would make a won- ‘Cheju-Do’ derful addition to the garden for its ZONES: 4–9 foliage, even if it never produced a SIZE: 2 to 4 feet tall and 1½ to 2 feet wide single flower, is yellow wax bells. CONDITIONS: Partial This hydrangea relative can grow to to full shade; moist, shrublike proportions in shady areas well-drained soil with moist, well-drained soil. Sturdy NATIVE RANGE: stems dressed in bold, sycamore-like Japan, China, Korea leaves add structure and texture to a shady border. In early fall, terminal, branched clusters of gumball-shaped flower buds open to butter yellow bells; these flowers have a prolonged bloom period. Yellow wax bells is a favorite of slugs and snails, so keep some diatomaceous earth on hand to deal with these unwelcome visitors.

When most people think of bugbane, they usually picture Actaea simplex (Zones 3–8), a late summer bloomer with several selections sporting stunning purple-black foliage. ‘Cheju-Do’ Japanese bug bane, which is from Cheju Island in South Korea, is a

lesser-known cousin that deserves gardeners’ attention. Preferring moist soil and shaded environ ments, ‘ChejuDo’ Japanese bugbane produces attrac tive clumps of dark-green lobed leaves that appear as if they had been dipped in resin. From underneath the glossy leaves emerge erect stems with pearl-like flower buds that open to small white stars, adding a striking vertical element to any shady border. The combination of its exceptional foliage and fall flowers makes this plant a must for any low-light spot.

In summer, weeping golden toad lily fades into the background of a woodland border with its shrubby, arching habit of glossy green leaves. Weeping golden It’s not until midfall when it grabs toad lily your attention with 1- to 2-inch- Tricyrtis macrantha long yellow, bell-shaped flowers. subsp. macranthopsis Bending over and looking inside the ZONES: 4–9 flowers will reveal maroon insides. SIZE: 1½ to 2 feet tall and wide Because these alluring flowers are CONDITIONS: Partial to best seen when looked at from full shade; moist, wellbelow, consider planting this toad drained soil lily where it can cascade over rocks NATIVE RANGE: Japan or a wall. Consistent moisture, rich, fertile soil, and dappled shade are Japanese a must in order to keep the leaves shrub mint looking their best. Crispy, brown Leucosceptrum leaf edges can be expected when stellipilum soil is allowed to dry out, so keep ZONES: 5–8 SIZE: 2 to 3 feet tall and the hose handy. 2½ to 3 feet wide

Japanese shrub mint is an under- CONDITIONS: Partial to used woodland perennial whose full shade; moist, wellhabit is very shrublike. All this drained soil perennial needs to be happy are NATIVE RANGE: Japan shade and soil that doesn’t dry out. Its semi-woody stems reach 3 feet tall, forming rounded mounds of coarsely toothed, fuzzy, hydrangea-like foliage. Deer ignore this plant, and it looks attractive throughout the growing season. By midfall, the end of each stem blooms with unique 3- to 4-inch-long angular inflorescences with bracts arranged in a herring bone pattern. From the bracts emerge small, pale lavender flowers that turn the inflorescences into sparkling wands.

Try out one of these unusual fall perennials, and watch as your autumn garden transforms from a fading, transitional group of plants into a spectacular display.

Andy Brand is the director of horticulture at Coastal Maine Botanical Gardens in Boothbay.