How to Grow Sunflower
Helianthus annuus
Sunflowers are vibrant warm-season annuals that thrive in full sun, reaching heights between three and twelve feet. Gardeners prize them for their cheerful blooms, tall stalks ideal for cutting arrangements, and edible seeds. These easy-to-grow plants add height and color to any garden bed while attracting beneficial pollinators.
📷 Wikipedia: Common sunflowerStarting Sunflower: indoors or direct sow?
🌾 Sow directly in the garden — Sunflower is not usually started indoors.
Direct sow seeds outdoors after the last frost; do not start indoors or transplant seedlings as they are sensitive to root disturbance.
Soil, care & harvest
Prepare a well-draining site with soil pH between 6.0 and 7.5. As a warm-season crop, sow seeds directly outdoors after the last frost when soil is warm. Plant seeds one inch deep at twelve to twenty-four inches apart. Germination typically occurs within seven to ten days under proper conditions.
Maintain spacing of twelve to twenty-four inches between plants to ensure good air circulation. These sturdy stems usually require no support, but staking tall varieties can prevent lodging in wind. Water deeply and infrequently, avoiding wetting the foliage. Apply mulch to retain moisture and feed sparingly if growth seems sluggish.
Watch for aphids or sunflower moths; encourage beneficial insects to keep populations low. Prevent rust by ensuring good airflow and watering at the base. Harvest seeds when heads turn brown and seeds rattle inside, usually seventy to one hundred days after sowing. Cut stems and dry them indoors before extracting the seeds.
When to Plant Sunflower
Planting windows vary by USDA hardiness zone. Look up yours by ZIP code.
| Zone | Start Indoors | Direct Sow | Harvest |
|---|---|---|---|
| Zone 1 | May – June | July – September | — |
| Zone 2 | April – May | June – August | — |
| Zone 3 | April – May | June – August | — |
| Zone 4 | March – April | June – July | — |
| Zone 5 | March – April | May – July | — |
| Zone 6 | March – April | May – July | — |
| Zone 7 | February – March | April – June | — |
| Zone 8 | February – March | April – June | — |
| Zone 9 | January – February | March – May | — |
| Zone 10 | January | February – April | — |
| Zone 11 | January | January – March | — |
| Zone 12 | January | January – March | — |
| Zone 13 | January | January – March | — |
