Ornamental · Asteraceae
Black-eyed Susan
Rudbeckia hirta
Set in full sun once, this golden-petaled daisy seeds its dark-eyed blooms back every year.
Full sun
Every 7–10 days
USDA 3–8
2–4 ft · 0.6–1.2 m
Overview
Black-eyed Susan opens a wide gold daisy across roadsides and meadows through much of North America. A single ring of slender yellow ray petals fans out around a raised dark brown center, a tight domed button of disc florets that forms the eye behind the name. The plant belongs to the aster family, throws up coarse, bristly stems at a fast clip, and that rough vigor is why it shows up in so many wildflower beds and cut-flower rows.
For all the way it seeds itself across a bed, Rudbeckia hirta is short-lived. Most plants run as an annual, a biennial, or a brief perennial that fades after a season or two. The narrow dark seeds it sheds each fall keep a patch going, so a single planting renews itself year after year without any help from you.
Given sun and free-draining soil, it asks for almost nothing. The hairy leaves and stems shrug off heat and the odd dry spell once the roots reach down, the flowers hold from early summer well into fall, and the spent heads dry to firm brown domes that feed birds through winter when you leave them standing.
Care
The short version: full sun and average, well-drained soil, with a deep drink every week or so until the plants settle in. Feed it sparingly, deadhead the fading gold flowers through summer to keep more opening, and let it self-seed for next year.
Light
Black-eyed Susan flowers hardest in full sun, six or more hours a day. It will take a little afternoon shade, but the more sun it draws, the more gold daisies open and the stiffer and more upright the bristly stems stand.
Water
Keep the soil evenly moist while plants are getting going, watering every 7 to 10 days when rain falls short. Once the roots run deep, it handles dry spells well. The one thing it will not forgive is soggy, poorly drained ground.
Soil
Almost any well-drained soil suits it, whether clay, loam, or sand, as long as fertility stays modest. A pH from 6.0 to 7.5 covers the full range it likes. Skip the rich, heavy ground, since lean soil gives you fuller, brighter flowers.
Humidity
Ordinary outdoor air is all it needs, so there is no number to chase here. Air movement matters more than moisture, because crowded, still conditions are what let a chalky powdery mildew settle on the leaf surfaces.
Feeding
This is a plant that does best a little hungry. Feed lightly, if at all, during the growing season, because too much nitrogen trades flowers for leafy growth. Lean soil and a modest hand bring the deepest gold bloom.
Pruning
Deadhead the spent flowers through summer and fresh gold daisies keep opening into fall. When blooming winds down, cut the coarse stems back, or leave the dark domed seed heads standing to feed birds and hold their shape through winter.
Size & spacing
Plants reach 2 to 4 feet (60 to 120 cm) tall on hairy upright stems, with a spread of 12 to 24 inches (30 to 60 cm). Give each one that much room so air moves through the foliage and mildew has a harder time taking hold.
When to plant
Black-eyed Susan runs on the warm season. Start seed indoors in late winter or sow it straight into the bed once frost has passed, and the gold flowers open from June through September, holding into fall as long as you keep deadheading.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: About 6 to 8 weeks before last spring frost (around March 1 in the St. Louis area)
- Plant: After last spring frost, or direct sow at last frost date
- Harvest: June to September, extending into fall with deadheading
Hardiness
USDA hardiness zones: 3–8
Temperature: down to -40°C
Troubleshooting
This is a tough, bristly plant, and most of its troubles show on the leaf surfaces or low on the stems. Catch them early and a quick fix usually settles things. Match what you see below, then act before it spreads.
Stems wilting and folding over right at the soil line
This collapse is southern blight, a soil fungus that takes hold in warm, humid weather and can fell a plant within days. At the stem base, look for a fan of white fungal threads and small round tan pellets the size of mustard seeds. An infected plant cannot recover, so lift it out with the soil around it, open the drainage, and keep mulch pulled clear of the stems.
Fix:
- Remove and destroy infected plants and surrounding soil
- Improve drainage
- Avoid mulch piled against stems
Ragged-edged holes torn through the young leaves
Slugs and snails chew these holes, working through the soft young leaves and grazing hardest when the air stays damp. A glistening silver slime trail beside the torn edges marks their path. Pick them off the leaves after dark, rake out the moist debris they hide beneath, and ring the seedlings with a barrier or trap.
Fix:
- Hand-pick slugs and snails
- Reduce excess moisture and mulch near crowns
- Use barriers or traps around young plants
A chalky white bloom dusting the leaf surfaces
That powder is powdery mildew, a fungus that settles in late in the season when plants stand crowded and the air hangs still. It coats the upper leaves in a flat gray-white film yet rarely kills the plant beneath it. Strip off the most heavily coated leaves, widen the gaps between plants, and water at the base so the foliage dries fast.
Fix:
- Improve air circulation by spacing plants
- Remove and discard affected foliage
- Water at the base to keep leaves dry
Toxicity
Good news for households with animals: black-eyed Susan is not toxic. It does not appear on the ASPCA's poison list, and pets, livestock, and children can be around it safely. The only thing to watch is the bristly, hair-covered foliage, which can leave sensitive skin a little itchy, so reach for gloves when you cut it back.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats Safe
Black-eyed Susan is absent from the ASPCA toxic list, so a cat that bites a leaf comes to no harm. The coarse, hair-covered surface may set off a brief moment of drooling, and nothing more.
Dogs Safe
A dog can mouth and chew the plant without harm. The stiff bristles along the leaves may scratch a tender mouth, but the tissue carries no toxin.
Horses Safe
Horses graze around Rudbeckia with no ill effect, as the plant holds no toxin known to trouble them.
Rabbits Safe
Rabbits can browse the foliage safely. The harsh, prickly texture of the leaves is the only thing that turns most of them away.
Livestock Safe
Cattle, goats, and sheep can share a pasture with it without risk, since nothing in the plant is poisonous to them.
Birds Safe
Birds pick at the dark, domed seed heads in fall, where the tightly packed seeds make a meal rather than a hazard. Spent flowers left standing feed finches through winter.
People Safe
The plant is harmless to handle, though the stiff, hairy stems and leaves can leave sensitive skin a little itchy where the bristles drag across it. Gloves while cutting it back remove the only real concern.
The bristly, hairy foliage and stems may cause mild skin irritation in sensitive individuals; wear gloves when handling.
Varieties
Plenty of Rudbeckia selections exist, but a few stand out for the size, color, or shape of their blooms. These are the ones worth knowing by name.
Prairie Sun
This 2003 All-America Selections winner opens large 5-inch blooms whose petals grade from deep gold at the base to pale lemon at the tips, circling an unusual light green cone in place of the usual dark eye.
Indian Summer
Stout, thick stems hold up enormous golden-yellow flowers that span a full 6 to 9 inches across.
Rudbeckia fulgida
The orange coneflower is the tougher perennial relative, creeping outward on rhizomes and persisting through zones 3 to 9 where the short-lived R. hirta rarely lasts.
How to propagate
Black-eyed Susan is among the simplest plants to multiply, whether you grow it from its slim dark seed or split an established perennial clump.
SeedEasy
Start indoors about 6 to 8 weeks before last frost, or direct sow at the last spring frost date · Blooms the first year from early spring sowing
Seed is the easy way in, and the seed itself is small, dark, and slender. Start it indoors 6 to 8 weeks before your last frost, or scatter it straight across the bed once the frost has passed, and an early spring sowing throws up flowers that same year. After that the plants take over, shedding seed each fall so new ones rise year after year.
DivisionEasy
Spring or fall for perennial clumps · Re-establishes within one growing season
Division works on the perennial types such as R. fulgida, since the short-lived R. hirta rarely builds a clump dense enough to split. Lift an established clump and pull it apart at the crown in spring or fall to keep it vigorous, and the divisions root back in within a single growing season.
Myths
Black-eyed Susan is a true long-lived perennial that comes back reliably for years.
Rudbeckia hirta is really an annual, biennial, or short-lived perennial. What returns each year are fresh seedlings, not a long-lived root, because the parent plants shed seed and wither while their offspring rise from the dropped seed. For one that comes back from the same crown season after season, plant R. fulgida instead.
Black-eyed Susan is poisonous to dogs and cats.
Rudbeckia appears nowhere on the ASPCA toxic plant database, and it is treated as non-toxic to pets. The only catch lies in the bristly, hair-covered foliage, which can leave sensitive skin mildly irritated.