🧅When to Plant Onion (2026)

Is Onion right for your USDA zone?

Onion is a cool-season crop, which means it thrives in the mild temperatures of spring and fall. Gardeners in zones 3a through 7b get the longest onion season — you can plant in early spring and again in late summer for a fall harvest. In warmer zones (8a-10b), grow onion as a winter crop from October through February when temperatures are coolest.

Onion needs about 100 days from transplant to harvest, so any zone with at least 114frost-free days can grow it successfully. Check your zone's specific dates in the table below.