When to Plant Onion in South Carolina

Growing Onion in South Carolina: Complete Guide

Onion (Allium cepa) is a warm-season crop that needs a head start indoors before South Carolina's last frost. Depending on your zone, South Carolina gardeners start seeds indoors between December 16, 2026 (Zone 9b) and February 8, 2027 (Zone 7b), then move transplants outside once their zone's last frost has passed — the zone table above has your exact dates.

Because South Carolina stretches across 5 USDA hardiness zones (7b, 8a, 8b, 9a, 9b), 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 100 days to maturity, Onion needs the indoor head start that South Carolina's growing season requires. Starting indoors ensures you have strong transplants ready the moment outdoor conditions are right.

Onion requires full sun (6+ hours) and moderate moisture. Southeastern summers are hot and humid; mulch heavily to retain moisture and shade roots during peak 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 South Carolina.