Black-Eyed Susan and Other RudbeckiasBy Gwen Bruno (gwen21)
September 6, 2012
|R. laciniata 'Hortensia'|
The plant variously referred to as a black-eyed susan, brown-eyed susan, brown betty, coneflower or gloriosa daisy was given its Latin name in 1740 by botanist Carl Linnaeus, who wished to honor his botany professor, Olaf Rudbeck. Early settlers found rudbeckia useful as a medicine, as did native Americans before them. Both roots and flowers were used to treat maladies such as earaches, worms, indigestion, burns and snake bites. Rudbeckia laciniata was among the native wildflowers transplanted to Europe by early visitors to American shores, and the British became the first to appreciate the plant’s garden uses. Eventually rudbeckia was welcomed into American gardening circles, its popularity increasing to the point that it was deemed “the darling of ladies who are partial to yellow” by 19th-century Canadian garden writer Annie Jack. The vigorous Rudbeckia laciniata ‘Hortensia’ or “golden glow” was so widely planted that it was sometimes affectionately called “the outhouse plant.”
| R. hirta 'Toto Rustic'|
Rudbeckias demand full sun if they are to bloom well -- shade will cause them to produce smaller and fewer flowers. They prefer a site that is moist and well-drained, but will tolerate less-than-ideal soil. Avoid over-fertilizing rudbeckia, because it can cause stems to weaken and flop. To prevent any problems with powdery mildew during periods of humid weather, provide plants with plenty of good air circulation. Keep rudbeckias dead-headed by pinching off flowering stems at their base. This will extend the plant’s flowering season and keep plants looking neat. You may want to allow some flowers to remain at season’s end for goldfinches, who relish the seeds that form in the flower’s “cone.” Create new plants by dividing larger clumps early in the spring, just as the plant emerges.
Any rudbeckia pairs well with other native plants such as echinacea and with various kinds of ornamental grasses. The vivid colors of the blooms combine well with blue or purple late-summer perennials like Russian sage or the aster ‘Purple Dome’. The nectar-rich flower cones make rudbeckia a good choice for a butterfly garden. Rudbeckia blooms are also excellent for cutting because of their long vase life. They are sensitive to ethylene, an odorless plant hormone. For the longest cut flower life, you should avoid exposing bouquets containing black-eyed Susan to ethylene sources such as ripening fruit.
Most of the 25 types of rudbeckia are native to the East and Midwest, but many are now found naturalized throughout much of the country. Flowers are most commonly yellow or gold, but also come in russet, mahogany and bronze. Blooms can be single, semi-double or fully double. Although both rudbeckia and echinacea are referred to as a coneflower, rudbeckia can be distinguished from echinacea, or purple coneflower, by its leaves, which are hairy and coarse in texture. Noteworthy varieties include:
R. hirta 'Chocolate Orange'
R. hirta, also called gloriosa daisy or yellow ox-eye daisy, is the floral emblem of the state of Maryland. Most types have an upright habit and reach between 3 to 4 feet high. This variety is a biennial or short-lived perennial hardy in zones 3 through 7. Hybrids include ‘Indian Summer’, which resembles a traditional daisy with extra-large yellow ray flowers around a dark cone, and ‘Cherokee Sunset’, displaying double flowers of orange, red, yellow, bronze or mahogany. Both are short-lived but re-seed themselves. ‘Cherry Brandy’ has rays of brilliant cherry red that darken to maroon closer to the flower’s deep brown cone. Instead of the usual brown center, the golden ray flowers of ‘Irish Eyes’ surround a light green cone. As its name suggests, ‘Chocolate Orange’, with rays of warm brown tipped with deeply-saturated orange, looks good enough to eat. At under a foot high, the compact ‘Toto’ series is a good choice for lining a walk or the front of a border.
R. fulgida 'Goldsturm'
Despite its common name of orange coneflower, the color of R. fulgida flowers is more accurately described as a deeply saturated gold. The species form often grows in colonies, with freely-blooming plants reaching 3 feet high and are hardy in zones 3 through 9. Popular cultivars of R. fulgida include ‘Goldsturm’ or “golden storm,” with abundant golden flowers on a 2 1/2- to 3-feet tall plant. Blooms begin in mid-summer and last for many weeks. ‘Viette’s Little Suzy’ is a prolific bloomer standing only 12 to 18 inches high, with the added attraction of foliage that turns purple in the fall.
A favorite form of R. nitida or shining coneflower is ‘Herbstonne’, which bears numerous blooms made up of warm yellow ray flowers surrounding a prominent central green cone. This cultivar can reach up to 7 feet high and works well with other back-of-the-border late-summer bloomers such as boltonia and joe pye weed. Another garden standout is ‘Goldquelle’, a smaller, 3-foot-high cultivar featuring double blooms of lemony yellow.
R. subtomemtosa 'Henry Eilers'
R. subtomentosa or sweet black-eyed Susan is native to moist meadows and lightly shaded woodlands, so it prefers more moisture and and can tolerate a bit more shade than most rudbeckias. Hardy in zones 4 through 8 and reaching from 3 to 6 feet high, sweet coneflower takes its common name from the vanilla-like scent of its soft, downy leaves. Blooms are clear yellow with a reddish-brown cone. The flowers of ‘Henry Eilers’, a R. subtomentosa cultivar discovered in Illinois, features ray flowers that curl, giving a quilled effect.
DG Member Photo credits:
Thumbnail of R. hirta by SandPiper
R. laciniata 'Hortensia' by GardenGuyKin
R. hirta 'Toto Rustic' by pixie62560
R. hirta ‘Chocolate Orange’ by alicewho
R. hirta ‘Irish Eyes’ by cat7
R. fulgida ‘Goldsturm’ by bob47
R. nitida ‘Herbstone' by GardenGuyKin
R. subtomentosa 'Henry Eilers' by wooffi
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