How to grow sunflower
Helianthus annuus · Asteraceae · Vegetable
When to plant sunflowers: the short answer
Start seeds indoors about 3 weeks before your last spring frost; plant out about 1 week after it; sow outdoors around the last frost date. Wait until the soil is at least 68°F; sunflowers sprout fastest near 80°F.
Zone 5: sow Apr 25 – May 14. Zone 7: sow Mar 31 – Apr 19. Zone 9: sow Feb 15 – Mar 6. See every zone.
Sunflower is a warm-season vegetable in the Asteraceae family, grown either from a direct sowing or from transplants. It wants full sun (six or more hours of direct light) and modest, occasional watering. From sowing to first pick is about 70–100 days. It is killed by frost, so nothing goes outside until the danger has passed and the soil has warmed.
Grower’s note: Grow branching types for cut flowers, single-stem giants for seed. Net the heads once the petals drop to keep birds off; harvest for seed when the back of the head turns yellow-brown. A deep taproot mines nutrients other crops cannot reach.
Sowing
Sow about 1.3″ deep, into soil between 68–90°F — germination is quickest near 80°F. Germination takes a week or two (7–14 days). For an early crop, start seed indoors about 3 weeks before your last spring frost and grow it under bright light.
Spacing & layout
Give each plant about 18″ along the row with roughly 30″ between rows. On a square-foot grid that is 1 per square foot. Allow at least 36″ of loose, workable soil for the roots. It grows well in containers at least 16″ deep.
Fitting it to your season
Sunflower needs roughly 70–100 frost-free days to crop. Where the season is shorter than that, start it indoors and choose the earliest-maturing varieties, or grow it in a container you can move under cover on cold nights. In long, hot-summer regions it can often be planted twice — once in spring and again in mid-to-late summer for a fall harvest.
Quick facts
Growth stages: how long sunflowers take to grow
From sowing to first harvest takes roughly 70-100 days (10-14 weeks), with seedlings appearing after 7-14 days in soil around 80°F.
When to plant sunflower
When to plant sunflowers by USDA zone
Dates worked out from each zone’s typical frost dates for 2026. Find your zone on the zone map, or pick your state below for dates from its own frost dates. Zones 11 and above are frost-free, so timing there depends on heat and rain instead.
| Zone | Last / first frost | Start indoors | Sow or plant out |
|---|---|---|---|
| Zone 3 | May 15 / Sep 15 | Apr 17 – May 1 | May 10 – May 29 |
| Zone 4 | May 10 / Sep 25 | Apr 12 – Apr 26 | May 5 – May 24 |
| Zone 5 | Apr 30 / Oct 5 | Apr 2 – Apr 16 | Apr 25 – May 14 |
| Zone 6 | Apr 15 / Oct 15 | Mar 18 – Apr 1 | Apr 10 – Apr 29 |
| Zone 7 | Apr 5 / Oct 25 | Mar 8 – Mar 22 | Mar 31 – Apr 19 |
| Zone 8 | Mar 20 / Nov 5 | Feb 20 – Mar 6 | Mar 15 – Apr 3 |
| Zone 9 | Feb 20 / Nov 30 | Jan 23 – Feb 6 | Feb 15 – Mar 6 |
| Zone 10 | Jan 30 / Dec 15 | Jan 2 – Jan 16 | Jan 25 – Feb 13 |
Companions
Cucumber, Sweet Corn, Pole Bean
Potato
Common problems
Pests: birds, squirrels, sunflower moth, aphids.
Diseases & disorders: sunflower rust, downy mildew, sclerotinia head rot.
Same family (Asteraceae)
Rotate these so they don’t follow each other in the same bed year to year.
Questions gardeners ask
When should I plant sunflowers?
Start seeds indoors about 3 weeks before your last spring frost; plant out about 1 week after it; sow outdoors around the last frost date. Wait until the soil is at least 68°F. The table on this page gives dates for each USDA zone, and the planting calendar gives dates for your own state or ZIP code.
How long do sunflowers take to grow?
About 70-100 days from sowing to the first harvest. Seeds germinate in 7-14 days, fastest in soil around 80°F.
How much sun do sunflowers need?
They need at least six to eight hours of direct sun a day.
What soil pH do sunflowers need?
A soil pH between 6.0 and 7.5. Test before adding lime or sulfur - see the soil pH and testing guide.
How far apart should I plant sunflowers?
Space plants about 18 inches apart in rows 30 inches apart, or 1 per square foot in a square-foot bed. Sow seeds about 1.25 inches deep.
Can I grow sunflowers in a container?
Yes. Use a container at least 16 inches deep with drainage holes and a good potting mix, and water more often than you would in the ground.
Figures are typical home-garden ranges from Cooperative Extension planting guides, cross-checked against multiple state sources. Your variety and conditions will vary.