Helianthus, Genus, annuus, Species,
- Genus & species
common sunflower
Overview
Helianthus annuus, the common sunflower, is a fast-growing annual in the aster family, reaching 3-10 feet (1-3 m) tall on stout, rough, hairy stems, with cultivated forms ranging from dwarf types under 2 feet (60 cm) to giants over 12 feet (3.6 m). The broad, heart-shaped leaves are 4-12 inches (10-30 cm) long, coarse-textured, and arranged alternately up the stem. In summer it produces large flower heads 3-12 inches (8-30 cm) across, each a disc of hundreds of tiny brown to purple fertile flowers ringed by bright yellow ray florets. Wild plants branch and carry many smaller heads, while many cultivated lines bear a single large head that tracks the sun when young. The heads are followed by flat, oval seeds in grey or black-striped shells, a major oilseed and snack crop. The plant grows quickly from seed in a single season, flowering from midsummer and dying at frost. It is native to North America and is grown worldwide for seed, oil, and cut flowers. Tall types may lodge in wind and are often staked in exposed sites.
Native Range
Native to North America, where wild forms grow across the central and western United States and into Canada and Mexico. It was domesticated by Indigenous peoples thousands of years ago for its edible seeds. It now grows worldwide as a crop and garden plant and is naturalized in many regions.Suggested Uses
Grown as a cut flower, a back-of-border and screen plant, and a seed and oil crop, with dwarf forms used in containers and bedding. The seed heads feed birds in autumn and winter. Rows of tall plants are used as summer screens and windbreaks in open gardens.How to Identify
Appearance
Size & Dimensions
Height3' - 10'
Width/Spread1' - 3'
Bloom Information
Blooms from midsummer into early autumn, mainly July through September, with each head lasting one to two weeks. Young flower buds and heads track the sun across the sky, settling to face east at maturity. The heads are heavily visited by bees and other pollinators and then fill with seed.
Detailed Descriptions
Flower Description
yellow with brown centerFoliage Description
greenGrowing Conditions
Sun Requirements
Requires 6-12 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
Water & Climate
Water Needs
Drought Tolerance
Drought tolerant when established
Care & Maintenance
Care Guide
Grows in full sun in moist, fertile, well-drained soil, though it tolerates poorer ground once established. Seed is sown directly after the last frost, about 0.5-1 inch (1-2.5 cm) deep, and germinates within one to two weeks. It needs steady moisture while young and is spaced 12-24 inches (30-60 cm) apart for full-sized heads. Tall types are prone to toppling and are often staked in windy sites. Birds, slugs, and fungal leaf spots are the main problems. As an annual it dies after seeding and is replanted each year.Pruning
No pruning is needed for single-stemmed types. Branching and multi-headed forms can be deadheaded to extend bloom and tidy the plant. Spent heads are often left standing for birds to feed on the seed.Pruning Schedule
Prune: August
summer
Container Growing
Suitable for container growing
Minimum container size: 3 gallons
