In the Garden:
Prairie Sun's 5-inch blooms have green centers surrounded by petals that fade from deep gold near the center to lemon yellow at the tips.
Rudbeckias for Every Garden
Newly released rudbeckia varieties don't seem to get the fanfare of, say, new echinaceas, but that doesn't mean they're not worthy of a closer look. The National Garden Bureau named 2008 "The Year of the Rudbeckia" for good reason. Rudbeckias, commonly called black-eyed Susans, bloom prolifically even in the most challenging garden conditions. This group of plants can be a little confusing, however, because it includes different classes of plants: true perennials; "half-hardy annuals" that may or may not return in subsequent years; and types that readily self-sow so that the flowers act as perennials, returning each year from newly sprouted seed. Here's some information to help you decide which rudbeckia is right for you.
There are about 25 species in the genus Rudbeckia, all native to North America. As a group, they are rated as hardy in USDA Hardiness Zones 3 through 10, although individual species and varieties may have more limited ranges. Rudbeckias, like many native flowers, attract birds and butterflies. In general, rudbeckia flowers have yellow petals with dark centers. The plants prefer full sun, and although established plants are relatively drought tolerant, they thrive with regular watering.
Rudbeckia hirta and R. fulgida are the two species most readily available to gardeners. Varieties of R. hirta tend to be short-lived and are often grown as annuals. Many of the most common rudbeckias fall into this category, including the newest varieties. Varieties of R. fulgida are true perennials.
Rudbeckia hirta Varieties
There seems to be some confusion about whether certain Rudbeckia hirta varieties are annuals, biennials, or short-lived perennials. Different sources classify varieties differently. However, most sources agree that the plants flower the first year if sown in early spring and readily self-sow. If your plants overwinter and rebloom, consider it a bonus. All the varieties described below make excellent cut flowers except the dwarf 'Toto'.
'Cappuccino' -- Abundant orange and red flowers cover this new, 18- to 20-inch tall plant from spring until early fall.
'Cherokee Sunset' -- A 2002 All-America Selection, Cherokee Sunset's 3- to 4 1/2-inch flowers may be yellow, orange, mahogany, and bronze, or a blend of colors. Grows to a height of 24 to 30 inches.
'Cherry Brandy' -- This new variety produces masses of single cherry red flowers with dark centers on 2-foot-tall plants. The variety won a Fleuroselect Novelty Award in 2007.
'Chim Chiminee' -- The flowers on this new 24-inch-tall variety have quilled (tightly rolled) petals in a range of classic fall colors -- yellow, orange, bronze, red.
'Denver Daisy' -- This 18- to 20-inch tall variety boasts extreme heat tolerance and is covered with 3- to 4-inch bright yellow blooms with a dark red ring at the center.
'Gloriosa' and 'Double Gloriosa' - These cultivars have very showy flowers up to 6" across, with yellow, gold, or reddish bronze rays. Plants grow to a height of about 24 inches.
'Indian Summer' -- The huge, sunflower-like blooms on this 36-inch-tall variety are bright yellow with dark brown centers. It was named the 2000 Fresh Cut Flower of the Year by the Association of Specialty Cut Flower Growers and was a 1995 All-America Selection.
'Prairie Sun' -- A 2003 All-America Selection, this 30-inch-tall variety has 5-inch blooms with green centers surrounded by petals that fade from deep gold toward the center to lemon yellow at the tips.
'Solar Eclipse' -- The flowers on this striking, 20-inch-tall, bi-color variety have yellow petals, each with a dark mahogany flame running down the center, and a dark brown center disk.
'Toto' - The flowers on this dwarf variety have full, rounded petals. Toto grows to a height of about 12 inches, and its tidy, compact habit make it good for border edgings and container plantings.
Other Rudbeckia Species
Rudbeckia fulgida is native to Missouri, where it thrives in a variety of habitats. The species grows to a height of about 36" and has a long bloom period, flowering from mid-summer until fall. A popular cultivar is 'Goldsturm' (R. fulgida var. sullivantii 'Goldsturm'), which was named the 1999 Perennial Plant of the Year. Goldsturm is smaller than the species, growing to a height of 18 to 30 inches, and is notable for its abundant flowers. Another R. fulgida variety, 'Early Bird Gold', grows 18 to 24 inches tall. 'Viette's Little Suzy' and 'City Garden' are even smaller, reaching only 10 to 15 inches in height.
Rudbeckia triloba, commonly called three-lobed or thin-leaved coneflower, is native to the prairies. More dainty in appearance than its cousins, the plant has an airy, open form and is completely covered with small yellow blooms with black button centers from July to October cousins. The tall (up to 48-inch) stems may need staking. Rated hardy in USDA Zones 5 through 7, R. triloba is considered a short-lived perennial, but it readily self-sows.
Rudbeckia laciniata is rated hardy in USDA Zones 3 to 9 and requires moister soils than other species. Athough it can grow up to 9 feet tall in the wild, it more commonly reaches a height of 3 to 4 feet. The daisy-like flowers have drooping petals and domed green centers. Native to much of the US, the plant's common names include cutleaf coneflower, green-headed coneflower, and tall coneflower. 'Goldquelle' is smaller, reaching 20 inches, and has yellow, dahlia-like flowers.
Rudbeckia maxima has unique, waxy blue-green foliage instead of the usual coarse, hairy leaves of other rudbeckias. Flowers have droopy yellow petals surrounding a tall brown cone, and flower stalks can reach a height of 7 feet or more. One of its common names, swamp coneflower, alludes to its preference for damp soils. Another common name is cabbage leaf coneflower. Native to warm, moist Southern woodlands, it is hardy in USDA Zones 5 through 9.
Two Rudbeckia occidentalis varieties, 'Black Beauty' and 'Green Wizard' are unusual in that they lack the yellow petals of most rudbeckias. Instead, the elongated black center cone is surrounded by the bright green sepals. They make a striking addition to both the garden and to cut flower arrangements.
Planted in full sun, rudbeckias are remarkably carefree and relatively drought-tolerant. Provide supplemental water the first season to help young plants get established. Rudbeckias are bothered by few insect and disease pests and need little or no supplemental fertilizing, especially if you amend the soil with compost before planting. Deadheading prolongs the bloom time, but be sure to leave some seedheads on the plants to attract birds and provide winter interest.
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