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Helianthus annuus 'Sonja' Sonja Sunflower

Edward F. Gilman, Ryan W. Klein, and Gail Hansen


Sunflower is a short-lived annual with large, striking flowers. Large types grow to 12 feet tall, but many garden cultivars are 4 to 5 feet tall. The familiar flowers have yellowish petals with a brown central disc and grow to 6 to 12 inches across. Plants are seeded in late winter to early spring in Florida, produce lovely flowers in mid-spring, and decline quickly in the heat by late spring to early summer. Plants in Florida installed in the fall can produce a nice flower display for several weeks in the fall.

Flower - Helianthus annuus 'Sonja': Sonja sunflower.
Figure 1. Flower - Helianthus annuus 'Sonja': Sonja sunflower.
Credit: Edward F. Gilman, UF/IFAS

General Information

Scientific name: Helianthus annuus 'Sonja'

Pronunciation: heel-ee-ANTH-us AN-yoo-us

Common name(s): 'Sonja' sunflower

Family: Asteraceae

Plant type: annual

USDA hardiness zones: all zones (Figure 2)

Planting month for zone 7: Apr; May

Planting month for zone 8: Mar; Apr

Planting month for zone 9: Feb; Mar

Planting month for zone 10 and 11: Dec; Jan; Feb

Origin: native to North America

Invasive potential: may self-seed each year

Uses: specimen; accent; mass planting

Availability: somewhat available, may have to go out of the region to find the plant

Shaded area represents potential planting range.
Figure 2. Shaded area represents potential planting range.


Height: 2 to 6 feet

Spread: 1 to 2 feet

Plant habit: upright

Plant density: open

Growth rate: fast

Texture: coarse


Leaf arrangement: alternate

Leaf type: simple

Leaf margin: dentate

Leaf shape: ovate

Leaf venation: pinnate

Leaf type and persistence: not applicable

Leaf blade length: 8 to 12 inches

Leaf color: green

Fall color: not applicable

Fall characteristic: not applicable


Flower color: yellow

Flower characteristic: showy


Fruit shape: oval

Fruit length: less than 0.5 inch

Fruit cover: dry or hard

Fruit color: black

Fruit characteristic: suited for human consumption; attracts birds

Trunk and Branches

Trunk/bark/branches: not applicable

Current year stem/twig color: green

Current year stem/twig thickness: very thick


Light requirement: plant grows in full sun

Soil tolerances: acidic; slightly alkaline; sand; loam; clay

Drought tolerance: moderate

Soil salt tolerances: unknown

Plant spacing: 18 to 24 inches


Roots: not applicable

Winter interest: not applicable

Outstanding plant: not particularly outstanding

Pest resistance: very sensitive to one or more pests or diseases which can affect plant health or aesthetics

Use and Management

The cultivar 'Valentine' has good uniformity and flowers well in Florida. It has a better overall appearance than either 'Floristan' or 'Hallo'. 'Floristan' has mahogany and light-yellow bicolored flowers; 'Hallo' has bright golden flowers; 'Valentine' has lemon-yellow flowers. 'Sonja' has big, yellow-orange flowers.

Pest and Diseases

'Valentine' is host to heavy infestations of sweet potato whitefly. 'Big Smile' had no infestation in trials conducted in central Florida. Leaf spots can cause severe leaf necrosis.

Publication #FPS-244

Release Date:February 12, 2024

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About this Publication

This document is FPS-244, one of a series of the Department of Environmental Horticulture, UF/IFAS Extension. Original publication date October 1999. Revised October 2023. Visit the EDIS website at for the currently supported version of this publication.

About the Authors

Edward F. Gilman, professor emeritus; Ryan W. Klein, assistant professor, arboriculture; and Gail Hansen, professor, sustainable landscape design; Department of Environmental Horticulture, UF/IFAS Extension, Gainesville, FL 32611.


  • Gail Hansen de Chapman
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