When to Plant Rosemary in Delaware

Growing Rosemary in Delaware: Complete Guide

Rosemary (Salvia rosmarinus) is a warm-season crop that needs a head start indoors before Delaware's last frost. Most Delaware gardeners begin seeds indoors around Sunday, January 25, 2026 and move transplants outside around Sunday, April 19, 2026, after the risk of frost has passed.

Because Delaware stretches across 3 USDA hardiness zones (7a, 7b, 8a), planting windows can shift by as much as two to four 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 120 days to maturity, Rosemary needs the indoor head start that Delaware's growing season requires. Starting indoors ensures you have strong transplants ready the moment outdoor conditions are right.

Rosemary requires full sun (6+ hours) and low (drought tolerant) moisture. Mid-Atlantic summers bring heat and humidity — ensure good air circulation and watch for fungal issues like powdery mildew.

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 Delaware.