Common Sunflower

Helianthus annuus

Family: AsteraceaeNative: North America

A tall, fast-growing annual plant with thick, hairy stems and large, coarse, heart-shaped green leaves. This seedling shows the characteristic rough texture and broad opposite-to-alternate leaf pattern.

Light: Full sun (6-8+ hours per day). These plants exhibit heliotropism, turning their heads to follow the sun.
Water: Water daily for young seedlings; established plants need about 1 inch of water per week. Over-watering can lead to root rot.
Growth: Annual herb; fast-growing, upright habit reaching 3-10 feet tall depending on variety.

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Care instructions

Requires full sun and deep, well-draining soil. Water regularly while establishing, but adult plants are somewhat drought-tolerant. Feed with high-nitrogen fertilizer in early stages, then high-phosphorus as it nears bloom.

Growing details

Sunlight

Full sun (6-8+ hours per day). These plants exhibit heliotropism, turning their heads to follow the sun.

Watering

Water daily for young seedlings; established plants need about 1 inch of water per week. Over-watering can lead to root rot.

Soil

Well-drained, loose soil with a slightly acidic to neutral pH (6.0-7.5). They have long taproots and need space to grow deep.

Hardiness zone

Zones 2-11 (grown as an annual)

Growth habit

Annual herb; fast-growing, upright habit reaching 3-10 feet tall depending on variety.

Bloom season

Mid-summer to early fall. Large composite flowers with yellow ray florets and dark brown or yellow disc florets.

Propagation

Easily propagated by seed sown directly into the soil after the last frost.

Common pests & issues

Susceptible to squirrels and birds eating seeds, powdery mildew, rust, and aphids. Supports tall plants with stakes if they are in windy areas.

Similar species

Jerusalem Artichoke (Helianthus tuberosus) which is perennial and has edible tubers, and various Rudbeckia species (Black-eyed Susans) which are generally smaller.

Interesting facts

Sunflowers were domesticated by Native Americans even before corn. They are also known for their ability to extract toxins, such as lead and arsenic, from contaminated soil.