Black-eyed Susan (annual)

Sun

Full sun; tolerates light shade but flowers less and may lean.

Water

Water regularly while establishing, then during prolonged dry spells. Plants in containers need more frequent watering.

Soil

Well-drained loam, sandy soil or clay that does not remain waterlogged; average fertility is sufficient.

Height

1-3 ft (0.3-0.9 m)

Spread

1-2 ft (0.3-0.6 m)

Flowers

Summer to autumn; usually golden yellow with dark brown centres. Garden strains also include orange, bronze, mahogany and bicoloured flowers.

Foliage

Rough, hairy green leaves, usually oval to lance-shaped, on bristly stems.

Growth

Fast; early-sown annual strains usually flower in their first summer.

Care needed

Low

• Plant out after frost danger has passed, spacing plants 12-18 in (30-45 cm) apart.
• Water at soil level when the soil begins to dry; avoid keeping the root zone constantly wet.
• Use little fertiliser in garden soil; excessive nitrogen encourages floppy growth and fewer flowers.
• Apply a thin mulch to conserve moisture, keeping it clear of the stems.
• Support tall strains early if the site is exposed to wind.

Pruning. Remove faded flowers back to a leaf or side shoot throughout summer to encourage more blooms. In autumn, leave some seedheads for birds or cut stems to ground level if you want to limit self-seeding.

Late winter

Sow an annual-flowering strain indoors about 6-8 weeks before your last expected frost; press seed onto moist compost without burying deeply.

Spring

Harden off seedlings gradually, then plant out after frost danger has passed.

Late spring

Alternatively, sow directly into prepared soil once it has warmed; thin crowded seedlings.

Summer

Water during dry spells and remove faded flowers regularly.

Early autumn

Allow selected flowerheads to ripen if you want seed or food for birds.

Late autumn

Remove diseased plants; leave healthy seed-bearing stems standing where practical.

• Plant in informal groups through sunny cottage borders for strong summer colour.
• Combine with ornamental grasses and purple coneflowers for a prairie-style planting.
• Use compact strains in large containers with good drainage.
• Include in cutting gardens for sturdy, long-lasting flower stems.
• Grow beside asters and salvias to extend the flowering season in pollinator borders.

Garden styles it suits: Cottage garden, Wildflower, Native meadow, Pollinator garden, New perennial (prairie) and Hot border.

Plant it with: Purple coneflower, Switchgrass, Little bluestem, Salvia, New England aster and Zinnia.

Wildlife: Open flowers attract bees, hoverflies and butterflies. Ripe seedheads feed finches and other seed-eating birds; avoid double-flowered strains if wildlife value is your priority.

• Powdery mildew: give plants full sun and good spacing, avoid drought stress, and remove badly affected foliage.
• Leaf spots: water at soil level, avoid crowding and clear away infected plant debris.
• Slugs and snails: protect young seedlings with barriers or wildlife-conscious controls and remove pests by hand.
• Crown or root rot: improve drainage, avoid overwatering and replace badly affected plants.

Not known to be toxic to cats, dogs or horses. No part is known to be seriously poisonous to people, but it is not an edible plant; eating it may cause stomach upset, and the hairy leaves and stems can irritate sensitive skin.

• Orange coneflower (Rudbeckia fulgida)

  A dependable clump-forming perennial that spreads by short rhizomes; its leaves are generally less bristly than those of Rudbeckia hirta.

• Brown-eyed Susan (Rudbeckia triloba)

  Usually taller and more branched, with many smaller flowers and lower leaves that are often three-lobed.

• Black-eyed Susan vine (Thunbergia alata)

  A twining climber with heart-shaped leaves and tubular, five-lobed flowers rather than daisy-like flowerheads.

Rudbeckia honours the Swedish botanists Olof Rudbeck the Elder and Younger, while hirta means hairy, referring to the plant's bristly leaves and stems.

Propagation. Grow from seed. For dependable first-year flowers, choose a strain sold for annual bedding and sow early indoors. Species seed may benefit from a period of cold, moist conditions, and some seedlings will not flower until their second year. Saved seed from named strains may not resemble the parent.

Accepted botanical name

Rudbeckia hirta

In the US and Canada

Native in Canada and the lower 48 states. Introduced in Alaska.

Native range

Alabama, Arkansas, California, Colorado, Connecticut, Delaware, District of Columbia, Florida, Georgia, Idaho, Illinois and Indiana.

Measured

Soil pH 6 to 7. Average height 58 cm.

Sources: GBIF (CC BY 4.0), USDA PLANTS and Trefle (CC BY 4.0). The care and design notes are LandscapeGPT's own.