When to Plant Onions in Delaware
In a typical Delaware location, start seeds indoors Jan 27 – Feb 10, then transplant outdoors Mar 10 – Mar 24. Across the state, the outdoor planting window starts as early as Mar 2 in Claymont and as late as Mar 22 in Hockessin.
Start seeds indoors 8-10 weeks before last frost (or use sets/transplants); set out 2-4 weeks before last frost, very cold-tolerant as seedlings.
Onions Planting Dates by City
| City | Start indoors | Transplant |
|---|---|---|
| Wilmington | Jan 27 – Feb 10 | Mar 10 – Mar 24 |
| Dover | Jan 24 – Feb 7 | Mar 7 – Mar 21 |
| Newark | Jan 27 – Feb 10 | Mar 10 – Mar 24 |
| Middletown | Jan 27 – Feb 10 | Mar 10 – Mar 24 |
| Bear | Jan 27 – Feb 10 | Mar 10 – Mar 24 |
| Brookside | Jan 27 – Feb 10 | Mar 10 – Mar 24 |
| Glasgow | Jan 27 – Feb 10 | Mar 10 – Mar 24 |
| Hockessin | Feb 8 – Feb 22 | Mar 22 – Apr 5 |
| Smyrna | Jan 24 – Feb 7 | Mar 7 – Mar 21 |
| Pike Creek Valley | Jan 27 – Feb 10 | Mar 10 – Mar 24 |
| Milford | Jan 31 – Feb 14 | Mar 14 – Mar 28 |
| Claymont | Jan 19 – Feb 2 | Mar 2 – Mar 16 |
| North Star | Jan 27 – Feb 10 | Mar 10 – Mar 24 |
| Pike Creek | Jan 27 – Feb 10 | Mar 10 – Mar 24 |
| Wilmington Manor | Jan 27 – Feb 10 | Mar 10 – Mar 24 |
| Seaford | Jan 31 – Feb 14 | Mar 14 – Mar 28 |
| Georgetown | Jan 24 – Feb 7 | Mar 7 – Mar 21 |
| Elsmere | Jan 27 – Feb 10 | Mar 10 – Mar 24 |
| Edgemoor | Jan 27 – Feb 10 | Mar 10 – Mar 24 |
| New Castle | Jan 27 – Feb 10 | Mar 10 – Mar 24 |
Showing the 20 most populous of 20 Delaware cities. Dates are estimates from each city's NOAA frost normals and university extension timing guidelines. See all Delaware cities.
Frequently Asked Questions
When should I plant onions in Delaware?
In a typical Delaware location, start seeds indoors Jan 27 – Feb 10, then transplant outdoors Mar 10 – Mar 24. Across the state, the outdoor planting window starts as early as Mar 2 in Claymont and as late as Mar 22 in Hockessin.
When is the last frost in Delaware?
The average last spring frost in Delaware ranges from March 30 in Claymont to April 19 in Hockessin, based on NOAA 1991–2020 climate normals.
How long do onions take to grow?
Onions typically take 90–120 days from planting to harvest. Start seeds indoors 8-10 weeks before last frost (or use sets/transplants); set out 2-4 weeks before last frost, very cold-tolerant as seedlings.
Other Crops in Delaware
- Tomatoes
- Peppers
- Eggplant
- Cucumbers
- Zucchini
- Winter Squash
- Pumpkins
- Watermelon
- Cantaloupe
- Corn
- Green Beans
- Peas
- Lettuce
- Spinach
- Kale
- Arugula
- Swiss Chard
- Broccoli
- Cauliflower
- Cabbage
- Brussels Sprouts
- Carrots
- Beets
- Radishes
- Turnips
- Garlic
- Potatoes
- Sweet Potatoes
- Asparagus
- Basil
- Cilantro
- Parsley
- Dill
- Oregano
- Thyme
- Sunflowers
- Zinnias
- Marigolds
- Cosmos
- Nasturtiums
- Dahlias
When to plant onions in other states