Rudbeckia is a classic All American treasure.
Widely known as black-eyed Susan, this North American native 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.
Rudbeckias were grown in English gardens many years before they were accepted by Americans as worthy garden plants. By the mid-1800s, 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.
Classification and Varieties
There are 25 species of Rudbeckia that 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.
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. 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.
Rudbeckia laciniata is a perennial type commonly called cutleaf coneflower or ragged coneflower. Its most famous representative is the old-fashioned heirloom ‘Golden Glow.’ Plenty of room is needed to grow this plant as it can spread 6 feet across. It is hardy in zones 4-8.
Petals of Rudbeckia fulgida (orange coneflower) are not true orange but a warm yellow. A popular choice has been Rudbeckia fulgida var. sullivantii Goldsturm until the new AAS Winner American Gold Rush came on the scene. It was trialed against Goldsturm and was found to be superior in habit, plant health, flower power, and bloom time. Bright golden-yellow flowers are on upright domed-shaped plants that grow to a compact 24” tall. This newest AAS Winner was especially praised for its ability to resist Septoria leaf spot.
The largest group of rudbeckias for the garden is Rudbeckia hirta. 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. 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.
A newer Rudbeckia hirta is Rudbeckia Amarillo Gold, a 2020 AAS Winner. It boasts of 4-6” blooms on compact and uniform 12-18” plants that are perfect for landscapes, bedding, and containers.
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. Or the older, 1961 AAS Winner Gloriosa Double sports rich, golden double flowers that are 3 ½” across with large black centers. This beauty also grows to 3’ tall.
How to Grow
Rudbeckias are easy to grow, low-maintenance plants 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 and mail-order seed sources.
Starting 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 it under plant lights. When seedlings have a couple of 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 of 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.
Rudbeckias 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.
- Soil—Rudbeckias prefer 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.
- 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.
- 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 provides adequate spacing between plants for good air circulation.
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.
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.
“This post is provided as an education/inspirational service of All-America Selections. Please credit and link to All-America Selections when using all or parts of this article.”