Gardening How-tos

Ravishing Rudbeckia—Coneflowers That Light up the Fall Garden

My first encounter with coneflowers (Rudbeckia), also called black-eyed Susans, was on a visit to a Long Island estate garden that once belonged to Woody Allen. A hedge of Rudbeckia nitida formed an eight-foot-high summer wall between two garden rooms and was alive with butterflies that flitted from flower to flower in an exuberant dance. The large daisylike coneflower blossoms had vibrant yellow petals and green conical centers, which jutted quirkily up in the air. Annual sunflowers bloomed in front of them in tints of mustard, wine, and creamy yellow. It was an unforgettable scene, one I relive every year when the coneflowers blossom in my own garden.

Rudbeckia 'Herbstonne'
Rudbeckia 'Herbstonne'

Blooming from late summer through frost, coneflowers bring saturated warm color and height—they grow anywhere from three to ten feet tall—to beds and borders. Coneflowers are easy to cultivate and good for cutting, and they mingle well with other plants as long as their flower colors are compatible. The bright yellow coneflower petals look great beside purple, deep blue, orange, red, burgundy, and even white blossoms. (They don't blend too well with flowers in the pink or magenta spectrum.)

The genus Rudbeckia consists of around 25 mostly perennial species (there are some annual and biennial species and forms) native to moist meadows and forest edges of North America. Named by Linnaeus to honor his teacher, Swedish botanist Olaf Rudbeck, the genus is part of the Asteraceae, or aster family, which includes such other daisy-flowered genera as Dahlia, Chrysanthemum, and Aster. Following are some of my favorite species and cultivars for the garden.

Best of the Bunch

The vertically unchallenged Rudbeckia 'Herbstonne' (also called R. nitida 'Autumn Sun') is a gem for the back of a border. It has large, gently lobed leaves and five-inch-wide blossoms. The yellow petals droop so that the green central cones stand up like noses. In my garden 'Herbstonne' grows happily in clay-based soil, rising seven to eight feet without any staking. Behind it, the deep green leaves of a tall cutleaf elderberry (Sambucus nigra f. laciniata) provide a good backdrop and make the coneflower's inflorescence sparkle.

'Goldquelle' is a four- to five-foot-tall cultivar of Rudbeckia nitida, with deep yellow semidouble flowers that are more voluptuous than those of 'Herbstonne'. Packed with petals, it looks more like a dahlia than a coneflower. 'Goldkugel' is a showy double-flowering form that resembles a chrysanthemum.

The tall coneflower, Rudbeckia laciniata, grows from five to ten feet high. Its leaves are more deeply cut than those of R. nitida and provide more interesting texture, but the plant's large, coarse, single flowers make it a less graceful addition to the garden. The cultivar 'Golden Glow' is a better option with its fully double all-yellow flower heads. However, it spreads quickly by runners and is a better candidate for a meadow than a border, where it can become a bit of a thug.

Cabbage leaf coneflower (Rudbeckia maxima) is in a class of its own, with striking 18-inch-long blue-green leaves. By mid- to late summer, the flowering stems rise up seven feet tall and are topped by dramatic coneflowers with two-inch-high noses and strongly drooping petals. This species loves moisture and heat and is ideal for a sunny damp meadow, but it can also be placed as an architectural accent in a mixed border.

Three-lobed coneflower, Rudbeckia triloba, usually a biennial, has all the presence of a shrub by midsummer. Its distinctive three-lobed leaves are furred. The plant grows five feet tall and wide and is filled with light, airy branches that bear hundreds of small bright black-eyed Susans. Picture a blazing beacon in the garden from which stems can be cut for bouquets with no loss to the plant's appearance. Like 'Goldsturm' (see below), it seeds around freely, sending pleasant surprises into next year's borders. Several medium-size coneflowers provide long-lasting color for the middle of borders.

The three-foot-high sweet coneflower, Rudbeckia subtomentosa, is one. This plant is named for the mild scent of anise that wafts from its three-inch-wide flowers. Its toothed gray-green leaves have downy undersides, and its stems are nicely branched—a benefit for bouquets.

Popularized by landscape designers Wolfgang Oehme and James Van Sweden, 'Goldsturm' orange coneflower (Rudbeckia fulgida var. sullivantii 'Goldsturm') belongs in every garden. This long-blooming yolk-yellow black-eyed Susan never flops, and it blooms well even in partial shade as long as it gets ample moisture. Flowers are three to four inches wide, and the plant grows three to four feet tall. 'Goldsturm' has seeded itself throughout my 2/3-acre garden and is always a welcome bright touch in late summer and fall.

For a small garden, or the front or middle of a narrow border, the compact black-eyed Susan, Rudbeckia speciosa var. newmanii, is a good choice. The plant grows only two feet tall. Its abundant flowers are slightly smaller than those of 'Goldsturm'.

Although the one- to three-foot-high gloriosa daisy, Rudbeckia hirta, is considered an annual and is easily grown from seed, it often self-sows for future years and brings some excellent cutting flowers to the mix. The cultivar 'Indian Summer' is popular for its six-inch-wide flowers with orange, red, and gold tints. Similarly, the Rustic Colors strain blends gold with burgundy for a Van Gogh look. 'Irish Eyes' is yellow with a green center, and 'Goldilocks' is a double yellow.

Rudbeckia Culture

Rudbeckia is easy to grow in any fertile garden soil and tolerates heavy clay as well. Sunny sites are ideal, but most black-eyed Susans will also bloom well enough in part shade. Most prefer regular watering where summers are dry.

To extend flowering and prevent self-sowing, deadhead the spent flowers—this also makes for a tidier-looking plant. If the old flowers are left alone, however, there are other advantages as well. For instance, the cones have ornamental appeal after the petals have dropped; birds enjoy the seeds in the winter; and you will be surprised by numerous seedlings next spring. Plants can also be increased by divisions made in early spring or late fall. When starting from seed, growers recommend a 50-50 sand and peat mix and find a better germination rate when seeds are chilled in the refrigerator for two weeks before sowing.

Companionable Combinations

I like the single-flowering coneflowers accompanied by similarly low-key perennials that would fit into a naturalistic meadow scene. Tall 'Herbstonne' likes a skirt of red switch grass, say Panicum virgatum 'Rehbraun,' or P. virgatum 'Shenandoah,' both with airy red flowers starting in late summer and red tints brightening their green leaves in autumn. Add some 'Gateway' joe-pye weed (Eupatorium purpureum ssp. maculatum 'Gateway') for a touch of purple in the mix.

Try double-flowering 'Goldquelle' with more cultivated-looking double dahlias in warm hues—red, orange, or burgundy—to match its style. Or contrast this shapely yellow coneflower with vertical spikes of purple fall monkshood (Aconitum henryi 'Sparks') for a striking combination.

To make the most of the cabbage leaf coneflower's (Rudbeckia maxima) distinctive blue-green leaves, combine it with purple-leaved golden loosestrife (Lysimachia ciliata 'Purpurea') and Penstemon digitalis 'Husker Red' for contrast, and repeat its foliage color with accents of plume poppy (Macleaya cordata) and globe thistle (Echinops ritro).

Since Rudbeckia triloba is so profuse, with hundreds of small vivid gold flowers smothering the shrub-size plant, it's hard to find a perennial with brilliant enough flowers to hold its own. Instead, balance the weight with the dark leaves of Aster lateriflorus 'Lady in Black', which will also bring out the coneflowers' black eyes. Or place a dark-leaved shrub nearby—'Diabolo' ninebark (Physocarpus opulifolius 'Diabolo') or 'Black Beauty' elderberry (Sambucus nigra 'Gerda')—for a similarly sultry contrast.

'Goldsturm' black-eyed Susan mixes nicely with any number of fall-flowering sedums at its feet. My favorites are the dark-leaved Sedum telephium 'Mohrchen' and the golden-variegated Sedum alboroseum 'Mediovariegatum.' Grasses are good companions; try blue oat grass (Helictotrichon sempervirens) for a cool effect.

Nursery Sources:

Johnny's Selected Seeds
Foss Hill Rd.
Albion, ME 04910
207-437-4301
www.johnny-seeds.com

Prairie Nursery, Inc.
P.O. Box 306
Westfield, WI 53964
800-476-9453
www.prairienursery.com

Digging Dog Nursery
P.O. Box 471
Albion, CA 95410
707-937-1130
www.diggingdog.com

Forestfarm
990 Tetherow Rd.
Williams, OR 97544-9599
541-846-7269
www.forestfarm.com

Barbara Blossom Ashmun writes a regular gardening column for Oregon's Portland Tribune. Her latest book is Married to My Garden, a collection of humorous and philosophical stories.

    Discussion

  • Angela Powell January 23, 2015

    Thank you for this great information on Rudbeckia ‘Herbstonne’. I am researching a question, and this is the best source I have found. Wish I lived closer so I could visit the garden!

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