Rudbeckia - Choosing and Growing Black-Eyed Susans

With there bright yellow petals and dark center disks, black-eyed Susans (Rudbeckia) have become garden staples. There is a great deal of variety within the species and most are true workhorses, with very few problems. The flowers are daisy-like and can be single, semi-double, and fully-double. You can tell them apart from coneflowers by their coarse-textured, hairy leaves.

The most commonly thought of Rudbeckia is the traditional Black-eyed Susan, a daisy-like flower with gold petals and a dark center seed head.

It also has the well-known scratchy, hairy leaves, which are not one of its best features. Most Rudbeckia varieties come in shades of yellow or orange, with a dark center seed head, but the flower heads are actually quite varied. There are Rudbeckia with petals in russet, bronze, and mahogany tones. For example, Rudbeckia "Cordoba" looks like a blanket flower. Rudbeckia "Maya" resembles a tall marigold and Rudbeckia "Cherokee Sunset" has an almost Chrysanthemum look.

Botanical Name

Rudbeckia

Common Names

Black-eyed Susan, Brown-eyed Susan, Conedisk, Conedisk Sunflower, Gloriosa Daisy Tall Coneflower

USDA Hardiness Zones

Hardiness will vary depending on the species and not all Rudbeckia are perennial plants. Those that are generally are reliably hardy in USDA Hardiness Zones 4 - 9.

Mature Plant Size

The size of Rudbeckia plants varies greatly, from dwarf (1 ft.) varieties like "Becky" and "Toto", to the giant Rudbeckia maxima, which can reach 9 ft.tall.

Growing conditions and weather also affect the mature size of plants.

Sun Exposure

You will get the best flowering from your Black-eyed Susan plants in full sun, but the plants can handle partial shade.

Bloom Period

Rudbeckia plants start blooming in mid-summer and can repeat bloom into fall, especially if kept deadheaded.

Seed started perennials can bloom the first year if started early enough.

Using Black-eyed Susans in Your Garden Design

Rudbeckia plants work equally well as a complement to blue and purple flowers, like Russian sage and Veronica or mixed in with other jewel tones, such as Sedum "Autumn Joy", Purple Coneflower and New England Asters. Rudbeckia also makes great cut flowers and even the seed heads will hold up well and look attractive in arrangements.

Rudbeckia Growing Tips

Soil: Black-eyed Susans are not particular about soil but do best in soil that is not too rich, with well-draining conditions.

Planting: Rudbeckia can be started indoors, from seed. Start seed about 6-8 weeks before last expected frost. Perennial varieties will germinate best if the seed containers are kept in the refrigerator or similarly cold place for 4 weeks after seeding. Then move them back to a warm spot (70ºF - 72ºF) until the seeds actually germinate.

Black-eyed Susans can also be direct seeded in the garden once daytime temperatures remain around 60ºF. If you do not wish to start your own seed, seedlings and plants can be purchased and transplanted.

Caring for Your Black-eyed Susan Plants

Black-eyed Susans are easy to establish, naturalize well, and require little maintenance other than deadheading.

Keep the plants well watered their first season, to get them established. Once established, the will be quite drought resistant.

Go easy on the fertilizer. Too much will result in weak stems and plants. A side dressing of compost should be all they will need.

Regular deadheading of the faded flowers will keep the plants in bloom longer. You can let the last flowers of the season remain on the plants to go to seed and feed the birds, but you will also get a good deal of self-seeding, which might not be a bad thing.

Plant division is only necessary if the clump gets too large for its space or if you want to make more plants. Rudbeckias don’t generally die out in the center and don't require frequent division.

Pests and Problems of Rudbeckia

Rudbeckia plants are deer resistant once their leaves become coarse and hairy, but tender young growth may get nibbled.

Powdery mildew will affect the leaves in hot, humid conditions. Minimize this by planting in full sun and thinning the plants to allow for good air circulation.

Suggested Rudbeckia Varieties to Grow

• Rudbeckia fulgida var. sullivantii "Goldsturm": The standard for Rudbeckia. Long blooming and virtually pest free. (2 ft.)
• Rudbeckia hirta "Cherokee Sunset": Double and semi-double flowers in shades of yellow, orange, red, bronze and mahogany. Short-lived, but re-seeds itself. (2 ft.)
• Rudbeckia hirta "Indian Summer": Traditional daisy-like, large yellow flowers. Short-lived, but re-seeds itself or grow as an annual. (3 - 4 ft.)
• Rudbeckia "Toto Rustic": A dwarf Rudbeckia in fall colors. There's also golden "Toto" & pale "Toto Lemon". (1 ft.)
• Rudbeckia maxima Giant Coneflower: 5-inch flowers and 1 - 2 ft. leaves on an imposing plant ( 5 - 9 ft.)