One of an occasional series of guides on growing popular plants. Other guides include azalea, redbud, Lenten Rose, peony, elephant ear, coleus, lantana, echinacea and calament savory.
A common name for rudbeckia is Echinacea, not to be confused with Purple Echinacea. Its most culturally resonant member is the biennial wildflower known as the Black-eyed Susan, but we’ll focus on hardy, longer-lived perennials that are well suited for use in the garden. As with calamine, rudbeckia is valued for its long flowering season at the hottest time of the year.
The best known of these is Rudbeckia fulgida and the selection known as Goldsturm, with each plant showing loads of large yellow daisies from July onwards.
Goldsturm and other varieties of fulgida grow to about 30 inches high and 24 inches wide. In rich soils and over time, clumps spread more widely and may require shrinkage. Other rudbeckias discussed below grow to eight feet or more.
Use and location
A few clumps can extend up to 10 or 12 feet, so they should be planted in spacious borders and flower beds. They are effective in combination with fine textured ornamental grasses such as pennisetum, calamagrostis and panicum.
Planting and maintenance
Rudbeckia fulgida will tolerate medium dry soils, but it is more vigorous and hardy in fertile, humus-bearing soil that retains moisture but is well-drained. Plants will take partial shade but need a site with good air circulation. This is because a fungal leaf spot disease called septoria can become established and quickly damage the foliage. Preventive fungicide sprays are effective, but the best remedy is to plant the rudbeckie in open, ventilated areas and ensure that all fallen leaves and stems are removed at the end of the growing season.
Besides Goldsturm, other varieties of R. fulgida include Goldschirm, Pot of Gold, and Viette’s Little Suzy. The latter grows to just 15 inches and is useful in small gardens.
Another garden-worthy species is Rudbeckia triloba, named after its three-lobed leaves. Its flowers are smaller but plentiful and attractively clustered. Triloba is short lived but sows prodigiously, allowing a colony to maintain itself. Unwanted seedlings can be removed in the spring, but avoid planting with other coneflowers to avoid confusion. The triloba will take over.
Rudbeckia triloba. (Center of Mount Cuba)
Rudbeckia subtomentosa Henry Eilers. (Center of Mount Cuba)
Rudbeckia maxima. (Center of Mount Cuba)
Rudbeckia Goldsturm. (iStock)
TOP LEFT: Rudbeckia triloba. (Center of Mount Cuba) TOP RIGHT: Rudbeckia subtomentosa Henry Eilers. (Center of Mount Cuba) BOTTOM LEFT: Rudbeckia maxima. (Mt. Cuba Center) BOTTOM RIGHT: Rudbeckia Goldsturm. (iStock)
The flower of the giant Echinacea, Rudbeckia maxima, consists of drooping yellow petals around a crimson-brown cone – a clear echo of the flowers of other rudbeckia. But the similarity ends there. Giant Echinacea is marked by large, blue-green oval leaves that give way to a thread-like, branching stem bearing flowers as tall as eight feet or more. Although each plant is relatively narrow, it shouldn’t require staking. It prefers more moisture than its lower brethren and as a garden plant it should be planted in groups to rise above neighboring perennials and shrubs. A single plant would appear clumsy and lonely.
A very underutilized echinacea is Rudbeckia subtomentosa, best represented by a variety named Henry Eilers. Its flowers have a pinwheel effect because each of the petals is rolled up in a tube. It is another imposing member of the clan, reaching six feet and flowering for weeks in the middle of summer. It needs a soil that retains moisture but is not wet.
Another great garden-worthy species is the cut-leaf echinacea, Rudbeckia laciniata, especially the cultivar Herbstsonne (Autumn Sun), which blooms from late July to October. It is a valuable part of the perennial and ornamental grass border planted to take the garden from late summer to fall.
Main illustration by Washington Post staff / iStock / Mt. Central Cuba. Icon illustrations by Jeannie Phan.