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Black-eyed Susans (Rudbeckia)
Beloved by pollinators, black-eyed Susans (Rudbeckia hirta) generally bloom from June to September (or longer!), often blanketing open fields with their golden-yellow beauty.
Learn how to care for this native wildflower, when to cut it back, and how to save seeds for replanting.
The “black eye” of black-eyed Susans refers to the dark brown center of their daisy-like flower heads. A member of the aster family, Asteraceae, and native to eastern North America, they have become naturalized in Zones 3 to 9. While some species of black-eyed Susans have additional names, such as Gloriosa daisies, they all belong to the Rudbeckia genus. The popular Rudbeckia hirta is treated as a short-lived perennial.
Black-eyed Susans grow 1 to 3 feet tall or more, with leaves 6 inches long, stalks over 8 inches long, and flowers 2 to 3 inches in diameter. In the garden, they do well in landscapes, borders, butterfly gardens, or containers. They are also outstanding cut flowers.
Butterflies, bees, and other insects are attracted to the flowers for the nectar. As they drink the nectar, they move pollen from one plant to another, causing it to grow seeds that can move about easily with the wind. “The Silvery Checkerspot butterfly uses Rudbeckia species as a host plant,” explains the University of Maryland. “Seed is consumed by songbirds, especially goldfinches.”
Planting
When to Plant Black-eyed Susan
- Set new plants out in the spring after all danger has passed, or plant in the fall. The optimal soil temperature for germination is 70° to 75°F. Do not plant in the hot summer.
- If planting by seed, sow seeds about 6 weeks before the average last frost.
Where to Plant Black-eyed Susan
The black-eyed Susan thrives in full sunshine. It tolerates partial sun, but it will not bloom as reliably. It’s best if the soil is fertile (not poor), though this plant can tolerate tough conditions.
How to Plant Black-eyed Susan
- Plants should be set 18 inches apart. Remove weeds and loosen the soil. Make a hole a few inches wider than the plant and set it in the hole; backfill it with soil, tamp gently, and water it well.
- If planting from seed indoors, sprinkle seeds on top of the regular seed starting mix. Do not cover the seeds, as they need light to germinate. Plant your seedlings outdoors after any danger of frost has passed. Since black-eyed Susans can spread between 12 and 18 inches, plant seeds closer to prevent lots of spreading, or plant further apart to make a nice border and to prevent the spread of disease.
- Black-eyed Susan spreads by self-seeding (after the first year) and underground rhizomes; this can result in it overtaking other nearby flowers.
Types
As well as the traditional black-eyed Susans, which grow 1 to 3 feet tall (or more), there are dwarf varieties that reach no more than 1 foot (perfect for containers). Varieties can be annual, biennial, or perennial.
The popular roadside Rudbeckia hirta with showy yellow flowers is a biennial in the wild but is treated as a short-lived perennial in the garden. It self-seeds abundantly, naturalizing easily. If you sow seeds 6 weeks before the last frost date, you’ll see flowers in the first year, and they may return a few more seasons (but you can’t always count on it). Some of its many hybrids include:
- ‘Autumn Colors’: yellow, orange, red, and brown flowers; 18- to 24-inch stems
- ‘Becky Mixed’: lemon-yellow, golden-yellow, dark red, and reddish-brown flowers; 10- to 16-inch stems
- ‘Prairie Sun’: All-America Selections winner; 4- to 6-inch bright orange flowers that fade to yellow at the tips; 28- to 33-inch stems. See AAS winning Rudbeckia varieties!
- ‘Sonora’: large golden flowers with big, chocolate-brown centers; 12- to 16-inch stems
- ‘Toto Gold’: dwarf type; classic yellow flowers with black centers; 12- to 16-inch stems; ideal for containers
There are also true, long-lasting perennials that will keep coming back and blooming year after year.
- ‘Goldsturm’ black-eyed Susans (R. fulgida ‘Goldsturm’), known for their longevity and a regular plant in late summer and fall gardens
- ‘Sweet’ black-eyed Susans (R. subtomentosa), bearing taller flowers and ideal for a more naturalized garden or meadow
- ’Gloriosa Daisy’ (R. hirta ‘Gloriosa’), 12 to 36 inches tall and tolerates partial shade; giant, bi-color double flowers.
Finally, some Rudbeckia varieties are annuals, such as the Clasping Sunflower (R. amplexicaulis), a low-growing plant for the front of a border garden.
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Hi, Sai: You can do this, but you really need to hurry. It works best in the fall when before the first frost, which usually is around Oct. 6 in Toronto. However, when we were in Toronto a couple of weeks ago (we could have helped you!), we believe there was scattered frost then, non? In any event, divide and remove them carefully and make sure they are well watered periodically after transplanting. Add some fertilizer to their new holes, too. And cover with a thick layer of mulch to better insulate during their first winter in their new home. Thanks for asking!
Hi, Yemmit: Make sure that your Susies get one really good watering each week. Otherwise, back off. Leave the seedheads on for wildlife, plus to help you reseed for next year. Whether they come back, time will tell. You will need to remove Iris from the ground, divide, and clean, then get back into the ground well before first frost (use the Frost Dates tool under Gardening above). Again, time will tell. We wish your ladies well!
Hi, KV: If it's possible (i.e., they are not too intermixed/-mingled with your other plants), try cutting back on their waterings (twice a week) but watering very deeply in order to encourage deep roots. Water in the morning, and only if they look wilted then. Otherwise, continue to take pleasure in the blooms' beauty and understand that it's often just the nature of these ladies' leaves to get bedraggled in summer's heat (don't we all?), not to mention get all tuckered out from producing their beautiful flowers.
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