Flowers

How to Grow Annual Black-Eyed Susan: Planting, Spacing, Care & Bloom

Quick answer

Start indoors up to 8 weeks before frost (Clemson). Plant annuals outdoors after last chance of frost (Clemson). This page is annual Rudbeckia hirta — not black-eyed Susan vine (Thunbergia).

Jump to

Updated

Annual black-eyed Susan (Rudbeckia hirta). Not black-eyed Susan vine (Thunbergia). Perennial Rudbeckia species are brief notes only — not a twin page.

Black-eyed Susan flower
Black-eyed Susan (Rudbeckia hirta). Photo: Krzysztof Ziarnek, Kenraiz, Wikimedia Commons, CC BY-SA 4.0 (resized).

Sourced from university extension guides. For dates where you live, use the ZIP planting planner.

Planting timing

Clemson: “Annual Rudbeckia are planted in spring after the last chance of frost.” Seed: sow early to mid-fall or early to mid-spring; spring seed often needs stratification about 3 months at 40°F. “Seeds can be sown indoors up to 2 months before frost.” Cover ¼ to ½ inch; germination about 2 weeks. (Clemson HGIC 1192) Planner: Start indoors last frost −8; Transplant last frost 0.

Depth and spacing

Clemson seed cover ¼–½ inch. Plants average about 2–3 ft tall and 1–2 ft wide; NC lists height about 2–4 ft. Space for air circulation.

Sun, soil and water

Full sun (>6 hr); tolerates partial shade; evenly moist, well-drained; drought/heat tolerant once established (Clemson). Avoid overfertile lawn-edge soil for best flower show (NC).

Care

Deadhead for rebloom (Clemson). Divide perennial types every 3–4 years spring or fall (Clemson) — section note for short-lived perennial stands. Remove dead foliage fall/winter/early spring.

Bloom

Late spring through early fall; excellent cut flowers (Clemson). No single days-to-bloom integer is sourced.

Pests and diseases

NC: powdery mildew; snails and slugs. Clemson: powdery mildew, leaf spots, stem rots — cultural spacing, drip irrigation, remove dead material. Aphids: soap or summer oil if needed; caterpillars: Bt kurstaki as labeled; Japanese beetles: handpick/soap/neem/Bt galleriae (UMN). Slugs: handpick or iron phosphate bait (UC IPM).

Related: ZIP planner · organic pest control

Frequently asked questions

When do I plant annual black-eyed Susan?

After last frost. Indoor start up to −8 (Clemson).

Same as black-eyed Susan vine?

No — Rudbeckia hirta vs Thunbergia; separate pages.

Do I deadhead?

Yes for rebloom (Clemson).

Sources