Sunflower

Helianthus annuus · Asteraceae

North American native with giant and branching types; feeds birds

Photo: George Chernilevsky, CC BY 4.0, via Wikimedia Commons

Sun: Full sun
Soil: Well-drained; tolerates poor soil
Soil pH: Best about 6.0-6.8; broadly near-neutral, and tolerates neutral to alkaline soil
Water: Moderate; drought-tolerant
Hardiness: Annual, grown in all zones (USDA zones 2-11)
Height and spread: 1-10 ft or more x 1.5-3 ft, by cultivar (dwarf types under 3 ft; giants 8-15 ft)

Guv's tipBirds and squirrels go for sunflower seed heads. Put netting over them and remove leaves near the heads to deter perching.

Through the year

When to plant

Sow direct after danger of frost has passed (early-mid May in central Illinois). The exact month depends on your local frost date

Harvest or flowering

Summer into fall (about Jul-Aug). Seed heads mature in late summer to fall

Pruning

None needed. Stake tall types in exposed sites

Making more plants

Seed

Watch out for

Pest

Birds / squirrels

Look for: Seed eaten from heads

What to do: Netting or other barrier over seed heads; remove leaves near heads to deter perching

Pest

Caterpillars, beetles, stink bugs, aphids

Look for: Chewed or damaged foliage

What to do: Vigorous plants usually tolerate; IPM approach, hand-remove as needed

Disease

Powdery mildew

Golovinomyces cichoracearum and related species

Look for: White powdery patches on leaves and stems

What to do: Proper spacing/air circulation, remove affected leaves; low-impact fungicide (sulfur, potassium bicarbonate, oil) if severe

Disease

Rust

Puccinia helianthi

Look for: Pale yellow/orange spots then cinnamon-brown pustules on leaves

What to do: Spacing, avoid excess nitrogen, fall cleanup, rotate, remove volunteers; resistant hybrids

Always read and follow the label on any treatment, and check it is approved for use where you live.

Safety and spread

Pets and people: Non-toxic to dogs, cats and horses (ASPCA). Rated safe by the University of Arizona, and not listed as poisonous by NC State Extension

Weed risk: Not on the federal noxious weed list. Can self-seed and become weedy

Checked against two or more reputable gardening sources. How we check our facts

Keep it by the back door

The Plant Doctor and the Guv's book

Printable pest and disease charts with real photographs, and all 50 USA plants in one book.

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