When to Plant Sunflower in New Hampshire

Growing Sunflower in New Hampshire: Complete Guide

Sunflower (Helianthus annuus) is a crop that grows best when sown directly in the garden. Depending on your zone, the right time to direct sow in New Hampshire falls between April 22, 2027 (Zone 6b) and May 22, 2027 (Zone 4a), once soil temperatures are consistently warm enough for germination.

Because New Hampshire stretches across 6 USDA hardiness zones (4a, 4b, 5a, 5b, 6a, 6b), planting windows can shift by as much as six to eight weeks from one end of the state to the other. Gardeners in the warmer southern zones can start earlier, while those in cooler northern zones should wait until the zone table above shows their last frost has passed.

With 80 days to maturity, Sunflower fits comfortably within New Hampshire's growing season in most zones. In the warmest parts of the state, a second planting later in the season may be possible.

Sunflower requires full sun (6-8 hours) and low-moderate (1 inch/week) moisture. In the Northeast, cool summers and moderate humidity can slow warm-season crops, so choose a sheltered, south-facing spot to maximise heat.

For the most precise planting dates tailored to your exact location, enter your ZIP code on our planting calendar or use the zone table above to find the schedule for your area of New Hampshire.