When to Plant Sunflower in Zone 6

Helianthus annuus

Last updated: Apr 29, 2026 · Sources: USDA, NOAA, Cooperative Extension
Action Plan

Plant Sunflower in Zone 6

  • Direct sow: Apr 29 — after last frost (Apr 15)
  • First harvest: Jul 18 (70–100 days after planting)
⚠️ Don't plant before last frost (Apr 15) — cold snaps kill young transplants.
Last frost
Apr 15
First frost
Oct 15
Growing season
183 days
Quick Facts
Sunlight ☀️ Full Sun
Water Needs 💧 Low
Spacing 24 inches apart
Planting Depth 1.0 inch
Min Soil Temp 55°F
Germination 7–14 days
Days to Maturity 70–100 days
Frost Tolerance No frost tolerance
Soil pH 6.0–7.5
Difficulty Easy
What you'll need — Zone 6
🛒 Sunflower — Seeds & Supplies
  • 🌱 Giant Sunflower Seeds
  • 🌱 Sunflower Bird Feeder
  • 🌱 Tall Plant Stakes

Search for these at your local garden center or nursery.

Growing Tips

  • Direct sow after last frost — sunflowers dislike transplanting.
  • Plant in groups for better cross-pollination and seed production.
  • Deadhead spent blooms to encourage branching varieties to continue flowering.
  • Leave seed heads on the stalk in fall for birds.
  • Thin to 12–24 inches apart — crowded sunflowers produce smaller heads.

Common Mistakes

  • Transplanting — sunflowers have taproots that don't survive disturbance.
  • Planting too deep — seeds only need 1 inch depth.
  • Growing near potatoes — sunflowers produce allelopathic compounds.
  • Not staking tall varieties — heavy heads snap in wind without support.

Companion Planting

Companion planting improves growth, deters pests, and makes better use of garden space.

✓ Good Companions

Cucumber Corn

✗ Avoid Nearby

Potato

Sunflower Schedule — All Zones

ZoneStart IndoorsTransplant Direct SowHarvest StartHarvest End
Zone 2 — — Jun 8 Aug 27 Sep 2
Zone 3 — — May 29 Aug 17 Sep 12
Zone 4 — — May 24 Aug 12 Sep 22
Zone 5 — — May 14 Aug 2 Oct 1
Zone 6 — — Apr 29 Jul 18 Sep 16
Zone 7 — — Apr 19 Jul 8 Sep 6
Zone 8 — — Apr 3 Jun 22 Aug 21
Zone 9 — — Mar 14 Jun 2 Aug 1
Zone 10 — — Feb 24 May 15 Jul 14
Zone 11 — — Jan 29 Apr 19 Jun 18

Other Zones for Sunflower

Zone 2 · Zone 3 · Zone 4 · Zone 5 · Zone 7 · Zone 8 · Zone 9 · Zone 10 · Zone 11

📚 Data Sources
Frost dates: NOAA Climate Normals 1991–2020, National Centers for Environmental Information.
Hardiness zones: USDA Plant Hardiness Zone Map, Agricultural Research Service.
Growing requirements: Cooperative Extension Services — NC State, Penn State, University of Florida IFAS.
Companion planting: Cornell University Cooperative Extension.
Data compiled from public agricultural sources. Always verify with your local extension office for micro-climate adjustments.