How to grow sunflower

Helianthus annuus · Asteraceae · Vegetable

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

When to plant sunflower

Companions

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.

Figures are typical home-garden ranges from Cooperative Extension planting guides, cross-checked against multiple state sources. Your variety and conditions will vary.