When to Plant Ornamental Allium in Delaware

Growing Ornamental Allium in Delaware: Complete Guide

Ornamental Allium (Allium giganteum) is fall-planted — it goes in the ground a few weeks before the first fall frost and overwinters for blooms the following spring. Depending on your zone, Delaware gardeners plant between September 3, 2026 (Zone 7a) and September 20, 2026 (Zone 8a).

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 210 days to maturity, Ornamental Allium fits comfortably within Delaware's growing season in most zones. In the warmest parts of the state, a second planting later in the season may be possible.

Ornamental Allium requires full sun (6+ hours) and low to moderate 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.