Perennial or annual
How to grow rudbeckia
Rudbeckia fulgida / R. hirta
Rudbeckias flower from July to October in full sun and soil that does not dry out. First check which kind you have. Perennial Rudbeckia fulgida is fully hardy: plant it in April or May, 45 to 60 cm apart, and divide every three to four years. Rudbeckia hirta is grown as a half-hardy annual: sow in heat in February or March and plant out after the last frost. Both sulk in dry ground and both need guarding from slugs while young.
- Hardiness
- Fully hardy (perennial types); R. hirta half-hardy
- Position
- Full sun
- Soil
- Fertile, moisture-retentive
- Ideal pH
- 6.0 to 7.0
- Water
- Moderate
- Feeding
- Moderate feeder
Sowing and planting rudbeckia
WhenPlant Apr to May; flowers Jul to Oct
Starting off
Plant pot-grown R. fulgida Apr to May; divide clumps in Mar or Oct every 3 to 4 years. Sow R. hirta Feb to Mar at 18 to 21 °C, 3 mm deep, germination 7 to 14 days; plant out May for flowers from Jul. R. fulgida seed sown Mar needs 3 weeks' chilling first.
Spacing and planting
R. fulgida 45 to 60 cm apart, annual R. hirta 30 to 45 cm; plant at pot depth. R. hirta is fine in a 30 cm pot; the perennial wants open ground.
Varieties worth growing
- R. fulgida var. sullivantii 'Goldsturm'
- The standard perennial black-eyed Susan: 60 cm, golden yellow with a dark cone, fully hardy and flowering for three months.
- R. fulgida var. deamii
- A little taller and looser than 'Goldsturm', very free-flowering, and it copes better with a dry spell.
- R. 'Herbstsonne'
- A 2 m perennial for the back of a border, with drooping lemon petals round a green cone; needs moist soil and a stake in exposed gardens.
- R. hirta 'Cherry Brandy'
- Annual with deep red flowers, 50 cm tall; raised from seed for pots and gaps in the border.
- R. hirta 'Prairie Sun'
- Annual with large golden flowers, pale tips and a green eye, on 80 cm stems that are good for cutting.
Rudbeckia month by month
Timings are for central England. Allow two weeks later in the north and on cold, heavy soil.
- January
Nothing to do. Leave the seed heads standing for the birds.
- February
Cut perennial clumps to the ground. Sow R. hirta in a heated propagator.
- March
Last sowings of R. hirta. Divide perennial clumps as growth starts.
- April
Plant perennials. Feed and mulch established clumps. Guard new shoots from slugs.
- May
Plant perennials. Harden off R. hirta and plant out late in the month.
- June
Water new plants weekly. Stake 'Herbstsonne' before it needs it. Light dressing of sulphate of potash as buds form.
- July
Flowering starts. Top-dress pots of R. hirta early in the month and water in.
- August
Deadhead to a side bud. Soak the roots in dry weather. Second and last top-dress for pots mid month.
- September
Deadhead early in the month, then leave the last flowers to form seed heads.
- October
Divide perennials if you missed March. Pull R. hirta after the first frost.
- November
Nothing to do. Leave the stems and cones on.
- December
Nothing to do.
Feeding rudbeckia
A moderate feeder. One balanced feed in April and a light dressing of sulphate of potash as the buds form in June are all it needs in the ground; annual kinds in pots get potash in the compost and two light top-dressings of the balanced fertiliser in summer. Steady moisture matters as much as any of it.
Moderate, a balanced feed and steady moisture for a long late-summer show.
Feeding plan
Planting perennial types
5 g per litre of root ball, dusted onto the roots: 10 g for a plant from a 2 litre pot. Once only.
April, established clumps and before planting annuals
About 100 g/m², the label rate: 25 g, two level tablespoons, round a clump covering 0.25 m². Fork in lightly and mulch over it. Once only; no repeat doses.
June, as the flower buds form, in the ground
20 g/m², the low end of the label, scattered dry and watered in: 5 g round a clump covering 0.25 m² (20 x 0.25). Once.
Potting R. hirta
5 g per litre of compost, the low end of the label: 60 g mixed into a 30 cm pot holding 12 litres.
Potting R. hirta
1 g per litre of compost, the low end of the label, mixed in with the base feed: 12 g for a 30 cm pot holding 12 litres. Once.
Early July and again in mid August, pots
2 g per litre of compost, the low end of the label top-dress: 24 g for a 30 cm pot holding 12 litres, scattered on the surface and watered in. The two dressings are 5 to 6 weeks apart, the label interval. Nothing after mid August.
Signs to watch
Floppy stems and lush leaves
Excess nitrogen
High-potash feed only
Wilting with yellow lower leaves in Aug
Dry roots and nitrogen short
Water and mulch
Fewer, smaller flowers after 4 years
Congestion
Divide in Mar
Pests, diseases and problems
Young plants and spring shoots stripped to the midrib or eaten off entirely
Slugs and snails, which favour rudbeckia above most border plants
Plant out annuals only once they are sturdy, patrol with a torch on damp nights in April and May, apply nematodes to moist soil from late March, and keep mulch away from the crowns.
White powdery film on leaves in August and September
Powdery mildew on plants that are dry at the root
Soak the roots weekly in dry spells, mulch in spring, and divide congested clumps so air can move through.
Angular dark brown or black spots on the lower leaves, spreading upwards
Fungal leaf spot, worst in warm wet summers and on crowded plants
Pick off the worst leaves, water at the base, and cut all growth to the ground in February and clear it away.
Annual plants rot at the base or stand still after planting out
Cold, wet soil: R. hirta planted before the ground has warmed
Hold plants in their pots until late May, harden off for 10 days, and plant into free-draining soil.
Shoot tips and flower stalks crowded with small insects, leaves sticky
Aphids
Rub them off or dislodge them with a jet of water; natural predators usually deal with the rest.
Pruning
Pruning and care
Deadhead to a side bud through Aug to Sep for more blooms, then leave the final heads for the birds. Cut the perennial to the ground in Feb; stake only tall R. laciniata types with a cane. Divide R. fulgida every 3 to 4 years in Mar to keep it vigorous; fully hardy, no protection. R. hirta is pulled after frost.
Good to knowDeadhead for more flower; leave some seed heads for birds.
Growing rudbeckia in pots
Annual Rudbeckia hirta is the one for pots: three plants in a 30 cm pot, about 12 litres, of peat-free multipurpose compost with the base feed mixed in. Stand it in full sun and water daily in hot weather, because the large leaves wilt quickly. Perennial R. fulgida spreads by short runners and soon fills a pot, after which it flowers poorly; grow it in the ground, or if you must, use a 40 cm tub of loam-based compost and split the plant every second spring. 'Herbstsonne' is too tall for any container.
Rudbeckia: common questions
Is rudbeckia a perennial or an annual?
It depends on the species. Rudbeckia fulgida, including 'Goldsturm', is a fully hardy perennial that returns every year. Rudbeckia hirta, including 'Cherry Brandy' and 'Prairie Sun', is a short-lived plant grown as a half-hardy annual in the UK and is pulled up after the first frost.
Should I cut back rudbeckia in autumn?
No, leave perennial rudbeckia standing until February. The dark seed heads feed goldfinches and look good in frost, and the old stems give the crown some shelter. Cut everything to the ground in February before new growth starts.
Why is my rudbeckia not flowering?
The usual causes are too little sun, dry soil, or an old congested clump. Rudbeckia needs at least six hours of direct sun and soil that stays moist through July and August. If a clump more than four years old has thinned out, lift and divide it in March and replant the outer pieces.
Sources
Growing information on this page was checked against these references in November 2026. Feeding rates are Dr Forest label rates.