Beloved by pollinators, black-eyed Susans (Rudbeckia hirta) generally bloom from June to August, 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.
What Are Black-eyed Susans?
The “black eye” of black-eyed Susans refers to the dark brown center of its daisy-like flower head. A member of the aster family, Asteraceae, and native to eastern North America, it has become naturalized in Zones 3 to 9. And while some species of black-eyed Susans have additional names—such as Gloriosa daisies—they all belong to the Rudbeckia genus.
Black-eyed Susans grow 1 to 3 feet tall or more with leaves of 6 inches, stalks over 8 inches long, and flowers with a diameter of 2 to 3 inches. 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.
In the garden, they do well in landscapes, borders, butterfly gardens, or containers. Also, they are outstanding cut flowers.
Black-eyed susans are Sun worshipers that forgive neglect and are tough-as-nails. However, avoid overcrowding these plants or watering their leaves (vs. soil level) which can lead to fungal disease.
Note that varieties can be annual, biennial, or perennial. The popular Rudbeckia hirta is treated as a short-lived perennial. See more about recommended varieties below.
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.
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.
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 in the hole; backfill with soil, tamp gently, and water well.
If planting from seed indoors, sprinkle seeds on top of the regular seed starting mix. Do not cover the seed, 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 to 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.
Check plants regularly to see if they need watering; avoid letting them dry out, and avoid excess moisture on the leaves, as it can encourage disease. (Provide plants with proper spacing.)
Deadhead the flowers any time of year (remove the faded/dead flowers) to prolong blooming and minimize self-seeding.
Remove dead plant material in the spring to reduce the risk of infection.
Divide perennial types every 3 to 4 years to ensure healthy plants and prevent excessive spreading.
Should You Cut Back Black-Eyed Susans
When it comes to black-eyed susans, we prefer to delay cutting back until spring.
This plant is a favorite with the wildlife, native insects, and birds with its dried seeds.
In addition, overwintering birds find protection in plant stubs and ground covers.
Plus, the mound of foliage will insulate the roots and protect the plant over winter.
However, black-eyed susans are a big reseeder. To avoid this, cut the spent flowers back just below the mound of foliage.
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 flowersis a biennial in the wild but 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
‘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.
‘Goldsturmm’ black-eyed Susans (Rudbeckia fulgida ‘Goldstrum’), known for its longevity and a regular plant in late summer and fall gardens
‘Sweet’ black-eyed Susans (Rudbeckia subtomentosa), bearing taller flowers and ideal for more naturalized garden or meadow
’Gloriosa Daisies’ (Rudbeckia hirta ‘Gloriosa’), 12- to 36-inches tall and tolerates partial shade; giant, bi-color double flowers.
Finally, some Rudbeckia varieties are annuals, such as Clasping Sunflower the (Rudbeckia amplexicaulis), a low-growing plant for the front of a border garden.
Cut flowers for display just before buds completely open. Use large blooms as centerpieces and smaller ones as accents. Change the water every day to keep them fresh. Vase life is 8 to 10 days.
How to Collect Seeds of a Black-eyed Susan
Once the seed heads are dry and brown, it’s time to clip some stems. Pop off the seed heads from the stems and toss them in a small jar; close the lid and shake it to loosen the seedheads. Then, dump the seed heads from the jar into a sieve with a white piece of paper below it. Break up the seed heads in the sieve with your fingers. The seeds will come off and fall through the sieve onto the paper! Fold the paper in half and carefully funnel those seeds into a paper envelope. Close and label the envelope and store it in a cool, dry place.