Rudbeckia is an all-American treasure. Widely known as black-eyed Susan or coneflower, this native to North America can be found growing as a wildflower in fields and along roadsides throughout the country. These reliable plants shine in the garden with an abundance of brightly-colored flowers reflecting the brilliant yellows and oranges of the summer sun. Rudbeckias are easy to grow, adapt to a wide range of garden conditions, have few insect or disease problems, and require only minimal care for a spectacular show of cheerful color during the summer and fall.

History

Rudbeckias were grown in English gardens many years before they were accepted by Americans as worthy garden plants. One of the earliest selections was Rudbeckia laciniata, known in the early 1600’s as Doronicum americanum. British plant collector John Tradescant was given roots of the wildflower by French settlers in the New World. The plant was shared with others including John Parkinson, the famous English herbalist and an early botanist, and was soon popular in English gardens. By the mid-1800’s, the rudbeckia had found its way back to America and was described by one early garden writer as “the darling of the ladies who are partial to yellow.”

Growing throughout the prairies and plains, it was used medicinally by many Native Americans to care for both people and horses. The roots and flowers were made into teas and compresses to treat a variety of ailments including snake bites, worms, earaches, indigestion, burns and sores.

In 1918, the black-eyed Susan was named the state flower of Maryland. The choice was not unanimously popular, however. Those in favor of the selection saw it as a beautiful flower that created splendid fields of color during summer and fall. In bloom it echoed the black and gold found in the coat of arms of Lord Baltimore, the founding proprietor of the Maryland Colony. The opposition noted that black-eyed Susan was not native to the state and many people saw it as a common weed. Today it is cherished throughout the state as a popular symbol of many awards, businesses and organizations.

Nomenclature

This premier group of plants was given its Latin designation in 1740 by famed botanist Carl von Linné, better known as Carl Linnaeus. The genus name Rudbeckia honored Linnaeus’s botany professor, Olaf Rudbeck, and Rudbeck’s father who had founded the botanical garden at Uppsala University in Sweden. Linnaeus told Rudbeck that “so long as the earth shall survive, and each spring shall see it covered with flowers, the Rudbeckia will preserve your glorious name.”

Rudbeckias have been known by a variety of common names including conedisk, conedisk sunflower, tall coneflower, and brown-eyed Susans. Today they are most often called coneflowers, black-eyed Susans, gloriosa daisies or rudbeckia.

Classification and Varieties

There are 25 species of Rudbeckia including perennials, biennials and annuals. All are native to North America and are generally found growing in the East and Midwest, though they have now naturalized throughout most of the United States and can be seen in fields and gardens from Canada to Mexico.

A member of the Aster family, the rudbeckia’s daisy-like flowers come in single, semi-double and fully-double forms in a range of colors from lemon-yellow to gold, chestnut, mahogany, and bronze, as well as multi-colored blooms. Most species are in bloom from midsummer through fall. Plants have coarse-textured, hairy green leaves.

Clasping coneflower (Rudbeckia amplexicaulis) is native to the southeastern United States but has naturalized throughout the country. This hardy annual has heart-shaped leaves that clasp the stem and bright yellow petals with reddish-purple markings that droop beneath the long, black, conical seed head. It reseeds freely and can form dense colonies in moist areas. It is most often used as a wildflower in prairie or meadow plantings and is often seen growing along roadsides. Clasping coneflower also looks good mixed with other sun-loving plants in an informal cottage garden.

Native to the eastern and midwestern prairies, the brown-eyed Susan (Rudbeckia triloba) is covered with a surplus of dainty, 1- to 2-inch yellow flowers with button-like black centers that fade to brown. Often called the three-lobed coneflower, this biennial or short-lived perennial is hardy in zones 4-7 but can also be grown as an annual. Plants are 2- to 5-feet tall depending on the growing conditions. Seeds of clasping coneflower and the brown-eyed Susan are offered by companies that specialize in wildflowers or packet seed companies.

Rudbeckia laciniata is a perennial type commonly called cutleaf coneflower or ragged coneflower. Its most famous representative is the old-fashioned heirloom ‘Golden Glow.’ This stately plant has beautiful yellow double flowers, and deeply cut leaves covering the 8- to 9-foot tall plants. Plenty of room is needed to grow this plant as it can spread 6 feet across. It is hardy in zones 4-8.

Despite its name, the petals of the orange coneflower (Rudbeckia fulgida) are not true orange but a warm yellow. A popular choice is Rudbeckia fulgida var. sullivantii ‘Goldsturm’ which translated means Golden Storm, no doubt referring to its masses of flowers with pale gold petals. This award-winning perennial variety has proven to be a workhorse in the garden. The 2- to 3-foot tall plants are long-lived and reliably produce an abundance of blooms from midsummer through September. ‘Goldsturm’ can be grown from seed or purchased as a container-grown plant. It is considered hardy in zones 3-9.

The largest group of rudbeckias for the garden is Rudbeckia hirta. Often called gloriosa daisy, there are many varieties available in a wide range of sizes. Flowers bloom from July until frost in shades of orange, orange-yellow and yellow. Rudbeckia hirta is a short-lived perennial and is grown as an annual in Northern areas. Plants are biennial or perennial in Southern regions.

‘Indian Summer’ is an All-America Selections (AAS) winner from 1995. It produces stunning 5- to 9-inch flowers on plants that reach about 3-feet tall. The golden-yellow flowers are ideal for cutting. Another AAS winner is ‘Cherokee Sunset’ (Rudbeckia x hirta hybrida). The semi-double and double, 2- to 4-inch, flowers bloom in shades of yellow, orange, bronze, and mahogany. Plants reach about 30-inches tall.

Several shorter varieties are available for growing in containers and in small gardens. ‘Becky’ produces dwarf, 10- to 12-inch plants with large, 3-inch flowers in orange, yellow and cinnamon bicolor, also available in a formula mix. ‘Toto’ is dwarf and compact with smaller flowers covering the 12- to 15-inch tall plants. There are several single colors available as well as a mix. Other popular varieties are ‘Corona,’ ‘Cordoba,’ ‘Sonora,’ and the fully double ‘Maya.’

Looking for something different? The 2003 AAS winner ‘Prairie Sun’ produces spectacular 5-inch blooms with golden-yellow petals tipped with a brush of lighter primrose yellow surrounding a striking, light-green center cone. The 3-foot tall branching plants can be grown in gardens and large containers. A similar variety with smaller yellow flowers and green centers is ‘Irish Eyes’ or ‘Green Eyes.’ They look spectacular in the garden and in bouquets.

One of the most unusual rudbeckias is the perennial Rudbeckia occidentalis ‘Green Wizard.’ These large, 3- to 5-inch flowers don’t have the typical colorful petals, only a ring of green sepals surrounding an elongated black cone center. They are striking in the garden and add unique beauty to arrangements, fresh or dried.

How to Grow

Rudbeckias are easy to grow, low-maintenance flowers that are ideal for beginning gardeners, yet their wide range of sizes, colors, shapes and forms appeal to the most experienced plantsperson. They are easy to start from seed, which is readily available from retail, mail order and Internet seed sources.

Rudbeckias grow best in full sun in average well-drained soil, but will tolerate light shade and dry conditions. In areas of heat and high humidity, powdery mildew can be a problem. Minimize the occurrence and spread of the disease by planting in an area with good air circulation and maintaining adequate spacing between plants. Rudbeckia is recommended as being deer-resistant, but slugs and snails like to eat the young plants.

Starting from Seed Indoors

Start rudbeckia seeds indoors about 6-8 weeks before the last frost date. Thoroughly moisten sterile, seed-starting mix then fill your flats, trays or pots to within ¼ inch of the top of the container. Put 1-2 seeds in each cell or small pot, then press seeds gently into the surface but do not bury them. Germination of perennial varieties started indoors may improve if placed in a cold area or the refrigerator for 4 weeks after planting the seeds, then moving them back into the warmer temperatures.

Place in a warm location until seeds begin to grow about 5-14 days later. A room temperature of 70ºF-72ºF is ideal for starting seeds. After seedlings appear, move the container to a bright, sunny window or place under plant lights. When seedlings have a couple sets of leaves, thin to the strongest plant by pinching or cutting excess seedlings at the soil line.

Before transplanting the tender seedlings into the garden they need to be hardened-off, allowing them to adjust to the outdoor conditions. Place seedlings outdoors in a shaded or protected location for short periods of time, about 4 hours per day to start. Each day, leave plants outdoors for a couple hours longer and gradually move into brighter light conditions. Check the soil often to make sure it’s moist and water if necessary. After 10-14 days plant in the garden.

Direct-seeding into the Garden

Black-eyed Susans are easy to start directly in the garden, generally when daytime temperatures are around 60ºF. Perennial varieties can be sown in fall or early spring. Scatter seeds then gently press them into the soil or cover very lightly with soil. Water regularly so the seedbed stays moist. As seedlings grow, thin to 6-8 inches apart.

Garden Preferences

• Soil—Rudbeckias tolerate a range of soil types but prefer a moist, well-drained soil that’s not too rich. Excess fertilizer can make plants weak and cause flower stems to flop. Water when the soil is dry to maintain even moisture.

• Sunlight—All rudbeckias thrive in full sun. They grow well in light shade, but flowers may be smaller and fewer in number.

• Spacing—The mature size of the plant determines the correct spacing. Allow 8-12 inches between rudbeckias being grown as annuals,18-30 inches for perennial varieties. Dwarf varieties can be planted closer together with 4- to 6-inch spacing between plants.

• Days to Bloom—Annual rudbeckias begin blooming about 10-12 weeks after planting seeds. Perennial varieties will bloom the first year in the garden if started early.

• Plant Care—To promote blooming and extend the flowering period, remove or deadhead faded flowers by pinching off the blooms at the base of the flower stem. If you want to attract birds, leave old flowers on the plant so they can go to seed. Be aware that rudbeckia often self-seeds, resulting in new seedlings sprouting up around the garden. Extra plants may need to be removed or transplanted to prevent crowding.

• Perennial rudbeckias require little maintenance. They do not need to be divided regularly like many other perennials because the center of the plant does not die out. However, if you want to move crowded plants or produce extra plants for your garden, divide clumps in early spring, just as growth begins to develop.

• Insects and Diseases—Rudbeckias are easy to grow with few disease or insect problems. Plants growing in hot, humid climates may be susceptible to powdery mildew or botrytis (grey mold) on their leaves. This can be minimized by planting in an area that receives plenty of light and provide adequate spacing between plants for good air circulation.

Garden Uses

Rudbeckias are versatile plants that add bright sunny color to perennial beds, mixed borders and containers. They can be used alone in mass plantings, as a border, or along a fence. Ideal for attracting wildlife, bees and butterflies are drawn to their colorful flowers while the ripe coneheads provide seed during the fall and winter to feed hungry birds, especially finches and chickadees.

Rudbeckias naturalize easily and are commonly planted in prairie restorations and prairie-style gardens. They look right at home planted with native prairie grasses including switchgrass (Panicum virgatum), little bluegrass (Andropogon scoparius) or Indian grass (Sorghastrum nutans). In the garden, they complement tall, ornamental grasses such as maiden grass (Miscanthus sinensis) and fountain grass (Pennisetum alopecuroides).

In a perennial border, the orange and yellow flowers of rudbeckia combine well with the blues and purples of Russian sage (Perovskia atriplicifolia), liatris (Liatris spicata) and fall-blooming asters (Aster novi-belgii or Aster novae-angliae).

Ideal for bouquets and arrangements, rudbeckia flowers stay fresh and colorful up to 21 days after being cut. Their daisy-like flowers are perfect in a cutting garden paired with other perennials such as purple coneflower (Echinacea purpurea), and shasta daisy (Chrysanthemum maximum). The dried coneheads add interesting shape and texture to everlasting arrangements and crafts.

And let’s not forget that black-eyed Susan is the classic flower for determining the essence of true love. The petals are perfect for answering the eternal question “she loves me, she loves me not, she loves me.”

The National Garden Bureau recognizes Janis Kieft as the author of this fact sheet. We wish to thank the rudbeckia experts who reviewed our text. Harlan and Shirley Hamernik of Bluebird Nursery Inc.; Bonnie Marquardt of American Takii, Inc.; Elisabeth Sahin of K. Sahin, Zaden B.V. and Rudolph Sterkel of Benary of America, greatly assisted our efforts to provide accurate information.