Sunflower in Zone 3a & 3b

Helianthus annuus

When to plant sunflower in zone 3b

Zones 3a and 3b share the same average frost dates in our data, so this page covers both.

Method: Direct sow: Direct-sow outside. Sunflower doesn't transplant well, or doesn't need the extra time indoors.

Spacing: about 2 square feet per plant (square-foot-gardening spacing). Mature height: 3-12 ft.

Sunflowers are one of the few flowers in a vegetable garden that does actual structural work: a single or branching stalk anywhere from 3 to 12-plus feet tall, topped with big daisy-form heads (yellow petals ringing a dark brown center, though some varieties run red or bronze), can serve as a living trellis for pole beans or climbing cucumbers, instead of building one out of stakes and twine.

How sunflower fits zone 3's season

Zone 3b's frost-free window runs about 98 days, from May 30 to September 5. Sunflower needs about 80 days from sowing to first harvest.

Good companions

• Bush Beans: Sturdy stalk can serve as a living trellis for pole beans once well established.
• Cucumber: Sturdy stalk can serve as a living trellis for climbing cucumbers.

Where to buy sunflower seeds

• Botanical Interests
• True Leaf Market
• Burpee
• High Mowing Organic Seeds

See why we recommend these suppliers →

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See it growing

Search YouTube for "growing sunflower" videos → (a live search, not a hand-picked video; results vary and aren't vetted by us)

← Back to the full zone 3b calendar · Full companion planting guide · Full plant profile · Plan your beds in the Garden Designer →

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Growing Sunflower in USDA zone 3b: when to start seeds indoors, when to direct-sow, and when to expect a bloom.

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