How much sun does Rudbeckia hirta need?

Full sun is ideal for the best flowering, though it can tolerate partial shade.

What kind of soil does it prefer?

It prefers well-drained soil and is adaptable to various soil types, including poor or clay soils.

Typically blooms from early summer through fall, with peak flowering in mid-summer.

Is it a perennial or annual?

It's often grown as an annual or short-lived perennial, depending on the climate and variety.

How tall does it get?

Height varies by cultivar, but generally ranges from 1 to 3 feet tall.

Plant guide

Black-eyed Susan.

Rudbeckia hirta

Pronounced rud-BEK-ee-uh HEER-tuh

Also known as Black-Eyed-Susan, Black-eyed Susan, Blackeyed Susan

Rudbeckia hirta is a cheerful, daisy-like wildflower native to eastern and central North America. It's known for its bright yellow petals and dark brown centers, bringing a burst of color to gardens and meadows. This plant is a favorite for pollinators and is quite adaptable to various conditions.

At a glance

Care level: Easy
Plant type: Perennial/Biennial/Annual (often grown as annual or short-lived perennial)
Light: Full sun
Indoor light: direct
Water: Every 7 to 14 days
Mature size: 1 to 3 feet tall, 1 to 1.5 feet wide
Growth rate: medium
Hardiness: USDA 3 to 9
Bloom time: Summer to fall

Care

Water regularly until established, then it's quite drought-tolerant. Deadheading spent flowers can encourage more blooms and prevent self-seeding if desired. It generally thrives with minimal intervention.

Watering: Water when the top inch of soil feels dry, more frequently in hot, dry weather.
Feeding: Generally does not require fertilizer; if needed, use a balanced, slow-release fertilizer once in spring.
Pruning: Deadhead spent flowers to encourage more blooms and prolong the blooming season.
Repotting: If grown in containers, repot every 1-2 years in spring.
Soil: Well-draining soil
Soil pH: Slightly acidic to alkaline (6.0 to 8.0)
Temperature: -29 to 35°C
Humidity: 20 to 50%
Drought tolerance: High
Lifespan: Annual or short-lived perennial.
Deer and rabbits: Moderate; deer and rabbits may nibble on it, especially when other food sources are scarce.

Signs it needs repotting

Roots growing out of the drainage holes.
Plant dries out very quickly after watering.
Water sits on top of the soil instead of draining through.
Reduced vigor or slower growth than usual.

Safety

People: Not considered toxic to humans, but it's best to avoid ingestion.
Children: No specific choking or handling hazards are noted, but ingestion should be avoided.
Contact allergens: Some individuals may experience skin irritation from the sap or foliage.
Airborne allergens: Pollen may cause mild respiratory irritation in sensitive individuals.
Edibility: This plant is not intended for human consumption.

How to identify it

Daisy-like flowers
Yellow ray petals
Dark brown central cone
Hairy stems and leaves
Rough, toothed leaves

Height: 0.3 to 0.9m
Spread: 0.3 to 0.45m
Leaves: Green, evergreen
Flowers: Yellow, Brown, 5 to 10cm
Fruit: Black, Brown, Late summer to fall

Common problems

Powdery mildew — A common fungal disease that appears as white, powdery spots on leaves and stems, especially in humid conditions.
Leaf spot — Fungal or bacterial infections causing spots on leaves, which can lead to premature leaf drop.
Aphids — Small, pear-shaped insects that feed on plant sap, causing distorted growth and potentially spreading disease.
Stem gall midges — Tiny flies whose larvae cause galls (swellings) on the stems, weakening the plant.

Growing it

Propagation: Seed, Division
When to plant: Spring, Fall
Overwintering: As an annual, it will die back with the first hard frost. If grown as a perennial, cut back the dead stems in late winter or early spring before new growth emerges. It may self-seed readily, so allow some spent flower heads to remain if you wish for volunteers the following year.
In containers: Yes, it can grow well in containers, especially dwarf varieties. A pot at least 8-10 inches in diameter is recommended.

Seed Starting Indoors

Sow seeds about 6-8 weeks before the last expected frost.
Lightly cover seeds with soil; they need light to germinate.
Keep soil consistently moist and at a temperature of 70-75°F (21-24°C).
Transplant seedlings outdoors after the danger of frost has passed.
Harden off seedlings by gradually exposing them to outdoor conditions for a week before planting.

Direct Sowing

Sow seeds directly into the garden after the last frost date.
Choose a location with full sun and well-drained soil.
Rake the soil surface lightly and scatter seeds.
Gently press seeds into the soil for good contact.
Keep the area moist until seedlings are established.

Division

If growing as a perennial, divide established clumps in early spring.
Carefully dig up the plant and separate the root ball into sections.
Ensure each section has healthy roots and shoots.
Replant the divisions in their desired locations.
Water thoroughly after planting.

Plant Rudbeckia hirta with other prairie natives that enjoy full sun and well-drained soil for a cohesive and low-maintenance garden.

Grows well with

Coneflower — They share similar growing conditions and bloom times, creating a beautiful prairie-like display.
Blazing Star — Their vertical flower spikes complement the daisy-like form of Rudbeckia hirta, and they attract similar pollinators.
Aster — Astors provide late-season color and bloom when Rudbeckia hirta may be finishing, extending the pollinator season.
Little Bluestem — This native grass provides structural contrast and thrives in the same sunny, well-drained conditions.

Keep away from

Overly dense shade — Rudbeckia hirta needs full sun to thrive and will become leggy and produce fewer flowers in deep shade.
Waterlogged soil — Poorly drained soil can lead to root rot and fungal diseases.

Similar species

Rudbeckia fulgida — Shares a similar appearance but is typically a more reliably perennial plant with slightly different foliage.
Helianthus annuus (Common Sunflower) — Both have large, daisy-like flowers with dark centers, but sunflowers are generally much taller and have different leaf shapes.
Coreopsis lanceolata — Both are cheerful yellow wildflowers that attract pollinators, but Coreopsis has more finely divided leaves and typically smaller flowers.

Science

Family: Asteraceae
Genus: Rudbeckia
Order: Asterales
Class: Magnoliopsida
Native range: Eastern and Central North America.
Conservation: Not of conservation concern.

It thrives in open, sunny areas like prairies, meadows, and roadsides, often colonizing disturbed soils.

Value to wildlife: nectar source, larval host plant
Pollinators: bees, butterflies, moths
Uses: Ornamental, Cut flowers, Pollinator gardens

Through the year

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Flowering

Fruiting

Foliage

Ecological indicators

Salinity: 2/9
Soil reaction: 6/9
Light: 8/9
Temperature: 7/9
Moisture: 4/9
Nutrients: 5/9

Taxonomy resolved against GBIF.

Questions people ask

How much sun does Rudbeckia hirta need?: Full sun is ideal for the best flowering, though it can tolerate partial shade.
What kind of soil does it prefer?: It prefers well-drained soil and is adaptable to various soil types, including poor or clay soils.
When does it bloom?: Typically blooms from early summer through fall, with peak flowering in mid-summer.
Is it a perennial or annual?: It's often grown as an annual or short-lived perennial, depending on the climate and variety.
How tall does it get?: Height varies by cultivar, but generally ranges from 1 to 3 feet tall.

Where the name comes from

The common name 'Black-Eyed Susan' refers to the dark, prominent center of the flower. The scientific name Rudbeckia honors the Swedish botanist Olof Rudbeck, and 'hirta' is Latin for 'hairy'.

Good to know

The 'hirta' in its scientific name means 'hairy', referring to its fuzzy leaves and stems.
It's a popular choice for naturalizing meadows and prairie restorations.
Drought tolerant once established.
Attracts beneficial insects like ladybugs.

Is your black-eyed susan looking unwell?

This page is a general guide. Pocket Botanist diagnoses problems from a photo of your actual plant, works out watering for your light and conditions, and reminds you when care is due.

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This guide was generated with AI and checked against GBIF taxonomy. It is general information, not horticultural or veterinary advice. Read about how we build these guides.