Growing Rudbeckia: How to Plant, Grow, and Care For Black-Eyed Susans
Rudbeckia is a flower that many gardeners are familiar with. But they usually call them by their more common name, the Black-Eyed Susan. These flowers are easy to grow, and bring a splash of beautiful yellow and black coloring to any garden bed. In this article, gardening and flower expert Taylor Sievers explains how to plant, grow, and care for Black-Eyed Susan flowers.
If you’ve ever taken a drive through the eastern and midwestern United States in mid to late summer, undoubtedly you’ve seen a familiar flash of taxi-cab yellow peeking out amongst the roadside weeds. In the fall, the potted chrysanthemums and pumpkins arrive at your local plant nursery, and so do pots of these charming flowers again, but this time they display themselves in yellow, orange, mahogany, brown, and every shade in between.
These yellow perennial flowers are all a part of the Rudbeckia genus, and they’re commonly called “black-eyed Susans,” “brown-eyed Susans,” “coneflowers,” or “gloriosa daisies.” I, for one, have always known them as “black-eyed Susans,” and the name surely fits. Traditional Rudbeckias have golden-yellow petals with dark center disks and, most of the time, hairy stems and leaves in a shade of dark green. They’re a staple in a pollinator patch, and they’ll reward you ten times over in a perennial garden bed.
Rudbeckias are beautiful not only in the landscape but also in a fresh-cut flower arrangement on your table. These plants are relatively easy to care for and also easy to multiply if you’re looking to expand your garden! Don’t miss out on these relatives of the sunflower (both are members of the Asteraceae family). The birds, bees, and butterflies love them, and so will you!
Rudbeckia Plant Overview
Plant Type Annual or Short-Lived Perennial
Native Area North America
Hardiness Zone USDA 3-9
Exposure Full Sun
Maturity Date 90 days to 2 years
Growth Rate Moderate
Plant Spacing 12-24 inches
Planting Depth 1/8 – 1/4 inch
Height 12-40 inches
Watering Requirements Moderate
Pests and Diseases Mildews, Aster Yellows, Aphids
Tolerance Temperate Climates
Soil Type Not Particular
Attracts Bees, Butterflies, Birds
Plant With Coreopsis, Echinacea, Liatris
Don’t Plant With Plants That Dislike Overcrowding
Species hirta, fulgida, triloba, maxima, & more
Rudbeckia Plant History
Rudbeckia species are native to North America, and for this reason, much of their history involves Native Americans. Specifically, the species R. hirta is mostly native to the United States. All parts of the black-eyed Susan plant were utilized by Native Americans.
The flowers were used to make green and yellow dyes. Root infusions were used to treat children with worms, sores, and colds. A leaf wash prepared by the Cherokee was used to treat swelling caused by worms. Root oozes were used to treat earaches.
Rudbeckia hirta was reportedly brought to Europe not long after Columbus’ trip to America. Linnaeus described and named the plant in 1753, naming it after his mentor Olaf Rudbeck. The species name hirta comes from the Latin adjective “hirtus” meaning “rough” or “hairy.”
There are many other species besides R. hirta, but this is the most popular species it seems in the genus. Much of the history of Rudbeckia is ascribed to R. hirta. Read on to learn more about the other Rudbeckia species and their specific characteristics.
Call them black-eyed Susans, brown-eyed Susans, coneflowers, or you-name-it—these flowers are all a part of the Rudbeckia genus. To clear up some confusion, I’ll talk about three of the main types of Rudbeckias you’ll commonly see sold at plant nurseries or markets in Fall or Spring. Each species has many unique cultivated varieties that we’ll discuss later in this article.
This species is often called “gloriosa daisy” or “black-eyed Susan” for the flower’s dark center disk flowers and cheerful yellow ray flowers (a.k.a. petals). Fun fact: The yellow hue of the petals is often described as “taxi-cab yellow.”
It seems the jury is out as to whether R. hirta is considered an annual flower, biennial, or perennial. Because there are many different varieties, their ability to come back each season can be impacted by many variables.
It appears that R. hirta is mostly considered an annual and can bloom well into the summer. It’s at least cultivated as such, because it flowers within the first year, while most biennials or perennials would not flower until their second year or beyond.
This species will readily self-seed. The leaves are alternate on the stem, and some varieties have toothed leaves while others have almost a smooth margin to the leaves. The center disk of the flowers is domed. The plant itself is stiff and branching, reaching up to 4 feet tall. R. hirta was originally native to eastern North America, but now has spread across the continent, being found along the banks of ditches or creeks and roadsides.
This perennial Rudbeckia is often called “black-eyed Susan” or “orange coneflower.” This species will form a basal rosette of green leaves that will persist over the winter, adding attractiveness to the landscape during its normally bare time.
The heads have brown-black flattened domes. This species will spread underground by rhizomes to form several clumps. Rhizomes are underground stems that spread horizontally, pushing out both shoots and roots. This species will reach up to 3 feet tall.
R. triloba, or “brown-eyed Susan,” is considered a biennial or short-lived perennial. This species also has a basal rosette of leaves that persists throughout the winter, and it can tolerate some shade. R. triloba is considered to be almost “weedy” in nature. If given plenty of room, it can bush out up to 4 feet.
The flowers are smaller than R. hirta and R. fulgida, topping out around 1 to 2 inches with shorter and wider petals than other Rudbeckias. One stem can contain several flowers as the plant heavily branches at the top of the stem into a burst of yellow and brown. The entire plant can reach up to 5 feet tall. The leaves are distinctly lobed and rough.
Other popular species are R. maxima (giant coneflower) and R. grandiflora (rough coneflower). R. maxima can take up to two years to flower and reach up to 5 feet. Some sources claim this species can reach 9 feet tall!
Depending on the species of Rudbeckia, plants can be propagated by seed or division. Most Rudbeckias are easy re-seeders in the garden, meaning they’ll go to seed naturally and propagate themselves easily, but if Rudbeckias are new to your garden, then you’ll want to read on to learn more about propagating these cheerful, easy-to-grow members of the daisy family.
Rudbeckia seeds require a cold period to germinate. You may be wondering… Why would seeds need a cold period in order to grow? Well, over time plants have developed mechanisms that help them survive and reproduce—to defy the odds, so to speak.
In order for seeds to germinate at the appropriate time (too early and they’ll freeze, but too late and they’ll be competing against many other species), seeds have developed an internal clock. After going through a cold, wet period for some species, the internal clock finally says, “Okay, it’s go-time.”
Rudbeckias are one of those species that need a cold, wet period for their seeds to germinate. For this reason, many gardeners will sow Rudbeckia seed in early to mid-fall. Another option is to sow seeds in early to mid-spring. However, seeds will need to undergo stratification if sown in the spring. Stratification is the process of subjecting seeds to cold and moist conditions for a period of time. You’re basically mimicking nature when you conduct this process!
To stratify seeds, you can accomplish this by sowing the seeds directly into pots or a seed-starting cell tray and placing them in the refrigerator for up to 3 months. Keep the seeds moist during this time, but not soggy.
Another option is to place seeds in a moist paper towel (or a moist mixture of perlite and vermiculite) inside a plastic bag and store them in the refrigerator. You’ll need to keep the seeds at about 40 degrees Fahrenheit during this time to make sure the seeds receive enough chilling hours.
When the time is up, you need to get those seeds germinating! Plant your seeds into a container or into the soil directly, or if you’ve already sown them in a pot or tray, place the tray in a warm area to begin “waking up” the seeds.
My personal success has been with freezing the Rudbeckia seed. About 2 weeks prior to sowing my Rudbeckia seed, I pop the seed packet into the freezer. After they’ve spent 2 weeks in the freezer, I then either direct sow them into the garden around the time of my estimated last frost or I sow them in a cell tray. This method has been rather successful for R. hirta, R. fulgida, and R. triloba varieties for me.
Some people say that they’ve had success without stratifying Rudbeckia seed. However, I’ve noticed that germination time is much more varied and takes quite a bit longer if I do not stratify Rudbeckia seed before planting. As a cut flower farmer, I need my seeds to germinate together so that all my plants are about the same size, so stratification is a must for me.
No matter what method you choose, you’ll want to make sure you only bury the seed at about ⅛ to ¼ inch depth. The seed is tiny, so if you’re starting indoors you may try surface sowing. This is accomplished by scattering and gently pressing your Rudbeckia seed into your seed-starting mixture with your finger. Adding a dusting of vermiculite on top will help keep your seeds moist until they germinate if you choose to surface sow.
Propagation by Division
Many Rudbeckia species and varieties are short-lived perennials, and this means you can propagate them by division! The best time to divide is in the fall or early spring. Your older plantings will thank you if you decide to divide them because often they can become overcrowded after 3 to 4 years.
To divide, take a sharp spade and drive it into the ground a few inches away from the existing plant. Pull your spade out of the soil and drive it into the ground again right next to your original spot. Continue to do this until you’ve made a ring around your plant. If you’re hitting a substantial amount of roots then try widening your circle. Eventually, you should be able to leverage the plant out of the ground.
Once you’ve dug up your Rudbeckia plant, it’s time to divide. Using a sharp spade or soil knife, split the plant and its roots into two or three sections. Discard any parts of the plant that look diseased or damaged at this time. Plant your divisions in their new locations, making sure to press the soil firmly around your new plant to remove any air pockets.
If you’d like, you can add some compost into your hole when replanting to help improve soil structure and soil fertility.
Division can be done every 3 to 4 years or whenever your plant is starting to look unhealthy. You’ll notice your perennial plants will start to have centers that are yellowed or dying off when they’re ready to divide.
When to Plant
Some plant nurseries will have potted Rudbeckias available during the fall when the potted chrysanthemums start to come out for sale. Fall is an excellent time to plant your Rudbeckia plants, but just make sure they have enough time before frosts become prevalent in order to establish themselves before winter. Potted annual Rudbeckia hirta varieties are best planted after your last estimated frost in the spring.
Sow seed in fall or stratified seed in early to mid-spring. Seeds can be sown as early as a few weeks prior to your last estimated frost in the spring if you’d like to sow them early in the garden. These plants are rather hardy in that aspect, but if you’re worried, then wait until your estimated last frost to sow Rudbeckia seed in the garden.
Gardening is all about experimentation and pushing the limits (at least for me), so don’t be afraid to step outside the box once in a while!
How to Grow
Rudbeckias prefer full sun (6 to 8+ hours of direct sunlight per day). Although this is their preference, some species can tolerate living in partial shade (2 to 6 hours of sunlight).
Plant your seedlings at least 12 inches apart. Rudbeckias can have a wide growth spread, depending on variety, so make sure to leave them plenty of room. Some varieties, like R. triloba, may require at least 24 inches between plants or more.
While Rudbeckias often prefer evenly moist, well-draining soil, they are typically not picky. Once established, these plants are often quite drought and heat tolerant, which makes this plant desirable for xeriscapes. Xeriscaping is a type of landscape design that requires little to no irrigation or maintenance, which is why this method is practiced frequently in arid regions.
Rudbeckia plants will tend to clump and spread, so make sure you’re dividing your perennial plantings every 3 to 4 years or “weeding out” undesired seedlings to keep your planting from becoming overgrown. Overcrowded plantings can result in a higher incidence of disease.
Deadheading the flowers will promote new flower growth. Once the flower has bloomed and begun to fade, you can clip the flower head at the base of its stem to keep your plant looking beautiful. These plants will continue to flower from Summer into Fall if you keep them deadheaded!
As the season moves into cooler seasons, you can tidy up your perennial Rudbeckias any time in the fall, winter, or early spring. Some people choose to leave the seedheads on the plant for the birds to feed on throughout the winter. Regardless, make sure to cut back any dead or decaying foliage and stems by early Spring. This will keep your garden healthy, tidy, and beautiful.
Likely what you’ll be harvesting from Rudbeckia is flowers for use in cut flower arrangements or the seeds for reseeding in your garden (or sharing with a friend).
Rudbeckia flowers can be cut as soon as the petals begin to unfold. This is the optimal time for vase life duration and to reduce pest damage. Perform the “wiggle test” on your flower stems to ensure you won’t have droopy stems in the vase.
The wiggle test is performed by grabbing approximately halfway down the stem and gently “wiggling” the stem. If the flower head flops too much, then you’ll likely have some drooping in the vase. If the flower head and neck of the stem appear more rigid, then it’s time to cut. Cut at the base of the stem or even deeper into the plant to promote the growth of more long, strong stems for cutting.
If you wish to harvest seed from Rudbeckia, wait until the flower has faded (or turned brown) and cut the seed head off, either leaving some stem or not, whichever is your preference. Hang the stem to dry or lay the seedhead out on a tabletop or screen in a warm, dry area with excellent air circulation.
After drying, use your fingers to gently crush the seedhead over a bowl or piece of paper, and the small, black seeds will drop readily. Pick out any large pieces of debris and store the seed in a cool, dry, and dark place until you’re ready to plant them.
Varieties of Rudbeckia
As mentioned above, there are several species of Rudbeckia that are readily grown and cultivated in home and commercial gardens alike. I’ve listed a few of the most popular varieties for the three main species highlighted earlier in this article, but know that there are many to choose from!
It is highly likely that you’ll see wild Rudbeckia species along roadsides and in ditches throughout North America, with plants blooming mid-summer into fall.
Rudbeckia hirta Varieties
- ‘Cherokee Sunset’ – This variety displays flowers in all shades of yellow, orange, bronze, and mahogany. The blooms are mostly double (extra petals) and are excellent cut flowers. The plant is usually 24 to 30 inches in height.
- ‘Goldilocks’ – This variety reaches up to 2 feet in height with double and semidouble golden-orange flowers.
- ‘Prairie Sun’ – This variety has golden petals with yellow tips and green centers. The flowers are large and the stems are extra strong with an average plant height of 30 inches.
- ‘Irish Eyes’ – This variety reaches up to 28 inches in height, but the centers are gold instead of brown. The petals are golden-yellow.
- ‘Indian Summer’ – Giant golden-yellow blooms 6 to 9 inches across with thick, sturdy stems. A beautiful addition to the cut flower garden.
- ‘Marmelade’ – This variety has a compact plant habit topping out at 2 feet tall with masses of 4 inch flowers. The blooms are a tangerine golden-orange.
- ‘Cherry Brandy’ – This variety is shorter, topping out at 1 foot in a container or 20 inches in the garden. The bloom color is a unique cherry-red or maroon colored flower.
- ‘Sahara’ – This variety tops out at 14 inches in a container and 20 inches in the garden with large semi-double to double blooms in colors of soft pink to red to caramel to coral-orange. Exquisite colors and a great candidate for perennial bedding or large planters.
- ‘Cappuccino’ – This variety is very unique with extra large flowers that have bronze, maroon, or cinnamon petals with bright golden tips. This perennial has a long blooming period and makes an excellent cut flower.
Rudbeckia fulgida Varieties
- ‘Goldstrum’ – This variety is the most popular of the R. fulgida species with the traditional Rudbeckia look of golden petals with dark center cones.
- ‘City Garden’ – This variety is ideal for container gardening as it tops out around 10 to 12 inches.
- ‘Little Goldstar’ – This variety is also ideal for container gardening, topping out around 14 inches.
Rudbeckia triloba Varieties
- ‘Prairie Glow’ – This variety blooms in the first year and has larger flowers with wiry purple stems. The flowers have bright yellow tips with a band of coppery-orange towards the center that fades to apricot with age. The plant will reach 40 inches in height.
- ‘Filou’ – This variety also reaches about 40 inches in height, but the flowers are pure yellow and the petals are more rounded. The flower will bloom after vernalization (a cold period).
Pests & Diseases
Some of the common diseases of Rudbeckia are powdery mildew, bacterial and fungal leaf spots, stem rots, downy mildew, white smut, and rusts. Rudbeckias are also prone to viruses and phytoplasma diseases, such as aster yellows. Common pests of Rudbeckia include aphids, two-spotted spider mites, cucumber beetles, and Japanese beetles.
Almost all of these diseases will result due to long periods of time in which water sits on the leaf. The best way to reduce the incidence of these diseases is by increasing airflow and circulation throughout your garden. This can be done by increasing spacing between plants, removing dead plant debris, and keeping your garden free of weeds.
Powdery mildew produces a white growth on the leaves and stems and typically appears later in the season. Downy mildew produces a white growth on the underside of leaves as well as yellowing and the overall decline of the plant.
Bacterial and fungal leaf spots will vary in the appearance of the spots, but essentially the spots will eventually cause death and dropping of the leaves.
Rusts are fungal pathogens that create red, orange, or yellow pustule-like spots on the leaves. Infected plants will decline in health over time due to the pathogen’s ability to redirect plant resources to itself.
Also, watering your plants at the base, instead of overhead, and watering in the morning versus the evening will help keep the plant’s leaves dry and reduce the incidence of disease.
White smut produces round, white spots about 1 centimeter in diameter. Over time the spots will turn brown and the affected leaf tissue will die. A white, powdery substance may be present as the spores begin to surface. The best way to control this disease is by removing the affected plants from the garden entirely.
Aster yellows are caused by the transmission of a phytoplasma that causes yellowing, stunting, and malformed flowers. This virus is transmitted by aster leafhoppers. If you suspect your Rudbeckia plant is suffering from aster yellows, promptly remove the entire plant from the garden and destroy it by burning or burying it. DO NOT compost the affected plant.
While Rudbeckia is known to repel deer, bugs still tend to love these flowers. Aphids will suck sap from plants and produce sugary excretions called honeydew that develop sooty mold growth, which creates unsightly black spots on the leaves and petals. Aphids can also transmit viruses. To control aphids, encourage natural predators like lady beetles or lacewings.
You can also purchase these beneficial insects and release them into your garden. A forceful stream of water sprayed onto the plant will also knock off adult aphids and kill small aphids, and if all else fails remove any heavily infested plants altogether from the garden.
Spotted Cucumber Beetles
Striped or spotted cucumber beetles are small beetles that will often feed on the flower and sometimes leaves of the plant. Spotted cucumber beetles are greenish-yellow with black spots, while striped cucumber beetles are yellow with black stripes.
The best way to prevent damage is by harvesting the flowers as soon as possible, just as the petals start to lift from the center disk. The use of trap crops will help shift the beetles’ focus onto an adjacent crop. I’ve found that cucumber beetles love plants in the amaranth family.
Japanese beetles are brown-black beetles with a metallic green head and thorax. They often arrive in mid-summer and can do significant feeding on leaves and flowers. Picking the beetles off your plant and dropping them into a bucket of soapy water will help control them in your garden. Some people use Japanese beetle traps, but there is controversy over whether these traps actually draw more beetles into the area.
Two-spotted spider mites are actually arachnids that resemble small ticks. They are very small (only about 1/50th inch long). Mite infestations are typical in hot, dry summer weather. They produce tiny white or yellow spots on leaves and as feeding becomes more intense, the leaves will turn bronze and eventually drop.
Check for webbing and symptoms on the leaves. Try to reduce stress on your plants, and this will help reduce mite infestations. Insecticidal soaps and horticultural oils can be used on the plants to treat mites. Also, spraying plants with a forceful stream of water will knock these pests off the plant physically.
Rudbeckia flowers and seedheads can be dried and used in dried flower bouquets and arrangements. Bundle the stems and hang them upside down in a warm, dry, well-ventilated space.
Seeds can be saved by collecting the seedheads after the flower has faded and turned brown. Dry the seedheads on a screen or tabletop in a well-ventilated area. Then, use your fingers to gently squeeze and pull apart the seedhead over a bowl or piece of paper. Remove the chaff and large debris and then store the seeds in a cool, dry place until you’re ready to sow the seeds.
Probably the most popular use of Rudbeckias is in the landscape or garden. These plants are highly adaptable to most soils and an excellent starting place for the amateur gardener. They tend to spread naturally via rhizomes or by re-seeding, so they are a favorite in wildflower or pollinator gardens. The flowers attract bees, butterflies, and beneficial flies, and the birds love to feed on the seedheads.
Flowers and seedheads of Rudbeckia are quite popular in cut flower arrangements, whether fresh or dried.
Some reported medicinal uses of Rudbeckia triloba include tinctures, washes, and teas. Flower petals used in teas are said to be used as a diuretic, tonic, and soothing agent. Teas have been administered for cardiovascular problems or given to children with worms. A wash can be made from Rudbeckia to treat bites, burns, and wounds. Creating a tincture of the root is said to help earaches.
Frequently Asked Questions
Does Rudbeckia come back every year?
new, healthy Rudbeckia plants. Some varieties of R. hirta are considered annuals. These will often readily self-seed in the garden if you desire these plants to linger for more than one year.
Can you grow Rudbeckia in pots?
Yes, you most certainly can grow Rudbeckias in pots! Try to choose more compact varieties, especially those within the R. fulgida species, like ‘Goldstrum,’ ‘City Garden,’ or ‘Little Goldstar.’ ‘Cherry Brandy’ and ‘Sahara’ are excellent choices for pots amongst the R. hirta species with their beautiful brownish-caramel colors.
How long does it take to grow Rudbeckia?
Rudbeckias are mostly considered short-lived perennials, so they will often form a rosette of leaves in their first year of growth, and then they require a cold period before they send up flower stalks in the second year. Some varieties are first-year flowering, which is an excellent choice for the impatient gardener.
Your seed company will often indicate on the plant description whether the variety is first-year flowering (often abbreviated as “FYF”). Another option to get a jumpstart is to start seeds in mid-summer so that seedlings will be mature for Fall planting before the first frost. Plant these seedlings out into the garden about 6 weeks prior to your first frost and they’ll overwinter and produce flowers the following summer.
What do you do with Rudbeckia in the winter?
For the most part, you can leave your Rudbeckias alone during the winter. However, at some point between fall and early spring, you will need to cut back any dead foliage or stems to maintain a healthy and tidy Rudbeckia planting. Some people like to leave seed heads on the plants throughout the winter for birds to feed on.
Who doesn’t love a reliable, showy, and pollinator-friendly plant in the garden? Rudbeckias are a staple in my landscaping, and I hope they’ll find their way into your garden or a patio pot as well! These plants are probably the least finicky plants I grow.
I love to watch the bees dance from plant to plant, and when I see a native variety along the roadside it’s a welcome summer sight. A pollinator-friendly garden is lacking if it doesn’t have a charming black-eyed Susan in its midst. If you’re a lover of bees and butterflies, or even if you like the idea of a beautiful plant that doubles as a cut flower, then I urge you to plant a Rudbeckia variety next season!