When Is the Last Frost in Delaware?
The average last spring frost in Delaware falls between April 2 and April 11 for most ZIP codes, with a statewide median of April 7. At the average date a later frost is still a coin flip, so tender plants wait for the safer 90% date.
| City | Last frost | 90% safe after | First frost | Growing season |
|---|---|---|---|---|
| Wilmington | Apr 7 | Apr 24 | Nov 4 | 209 days |
| Dover | Apr 4 | Apr 17 | Nov 4 | 214 days |
| Newark | Apr 7 | Apr 21 | Nov 2 | 208 days |
| Middletown | Apr 7 | Apr 21 | Nov 1 | 209 days |
| Milford | Apr 11 | Apr 28 | Oct 30 | 200 days |
| Smyrna | Apr 4 | Apr 17 | Nov 4 | 214 days |
| Seaford | Apr 11 | Apr 28 | Oct 30 | 200 days |
| Georgetown | Apr 4 | Apr 16 | Nov 6 | 217 days |
| Millsboro | Apr 4 | Apr 16 | Nov 6 | 217 days |
| Elsmere | Apr 7 | Apr 24 | Nov 4 | 209 days |
| Fenwick Island | Apr 7 | Apr 23 | Nov 2 | 209 days |
Last and first frost: 50% (median) dates of the last spring and first fall 32 °F night. 90% safe after: only a 10% chance of a later spring frost. First frost dates in January fall in the following winter. Each city uses the NOAA station nearest the ZIP code closest to its center.
Across all 7 Delaware weather stations with frost records, median last frost dates run from March 29 at Lewes, DE to April 11 at Greenwood 2 NE, DE. Elevation, valleys that collect cold air and distance from large water bodies explain most of the spread, so a garden a few miles from a listed city can differ by a week or more. The ZIP code lookup above uses the same NOAA data as the frost date calculator for every US ZIP code.
When Is the First Frost in Delaware?
The average first fall frost in Delaware arrives between October 30 and November 10 for most ZIP codes, with a median of November 4. Tomatoes, peppers, basil and squash are damaged at 32 °F, so harvest or cover them before then.
Fall frost can come early: Wilmington has a 10% chance of frost before October 21, Dover has a 10% chance of frost before October 23 and Newark has a 10% chance of frost before October 19. Hardy crops such as kale, spinach and cabbage tolerate light frosts and keep producing after the first frost date.
When to Plant Tomatoes in Delaware?
Transplant tomatoes in Delaware 1 to 2 weeks after the local average last frost, once nights stay above about 50 °F: Apr 14 – Apr 21 in Wilmington, Apr 11 – Apr 18 in Dover and Apr 14 – Apr 21 in Newark. Start seeds indoors 6 to 8 weeks before the last frost.
| City | Start seeds indoors | Transplant outdoors | Lowest-risk transplant |
|---|---|---|---|
| Wilmington | Feb 10 – Feb 24 | Apr 14 – Apr 21 | after Apr 24 |
| Dover | Feb 7 – Feb 21 | Apr 11 – Apr 18 | after Apr 17 |
| Newark | Feb 10 – Feb 24 | Apr 14 – Apr 21 | after Apr 21 |
| Middletown | Feb 10 – Feb 24 | Apr 14 – Apr 21 | after Apr 21 |
| Milford | Feb 14 – Feb 28 | Apr 18 – Apr 25 | after Apr 28 |
| Smyrna | Feb 7 – Feb 21 | Apr 11 – Apr 18 | after Apr 17 |
| Seaford | Feb 14 – Feb 28 | Apr 18 – Apr 25 | after Apr 28 |
| Georgetown | Feb 7 – Feb 21 | Apr 11 – Apr 18 | after Apr 16 |
| Millsboro | Feb 7 – Feb 21 | Apr 11 – Apr 18 | after Apr 16 |
| Elsmere | Feb 10 – Feb 24 | Apr 14 – Apr 21 | after Apr 24 |
| Fenwick Island | Feb 10 – Feb 24 | Apr 14 – Apr 21 | after Apr 23 |
Indoors: 6–8 weeks before the average last frost. Outdoors: 1–2 weeks after it. Lowest-risk: after the date with only a 10% chance of a later frost. Rules of thumb; check the 10-day forecast and wait for soil near 60 °F.
Tomatoes stall below about 50 °F at night and are killed by frost, so a week or two of waiting after the average date costs little. The tomato plant care guide covers light, watering and feeding once plants are in the ground.
What Can You Plant in Wilmington and When?
Wilmington's average last frost of April 7 anchors its spring planting calendar: peas and spinach go in from February 24, broccoli and lettuce transplants from March 10, and tomatoes, peppers and squash after April 14.
| Crop | Start seeds indoors | Plant outdoors | Frost tolerance |
|---|---|---|---|
| Peas | — | Feb 24 – Mar 10direct sow, 4–6 weeks before last frost | hardy |
| Spinach | — | Feb 24 – Mar 17direct sow, 3–6 weeks before last frost | hardy |
| Radishes | — | Mar 3 – Mar 17direct sow, 3–5 weeks before last frost | hardy |
| Onions (sets) | — | Mar 10 – Mar 24plant, 2–4 weeks before last frost | hardy |
| Potatoes | — | Mar 10 – Mar 24plant, 2–4 weeks before last frost | half-hardy |
| Broccoli & cabbage | Feb 10 – Feb 24 | Mar 10 – Mar 24transplant, 2–4 weeks before last frost | hardy |
| Lettuce | Feb 24 – Mar 10 | Mar 10 – Mar 24transplant, 2–4 weeks before last frost | hardy |
| Beets | — | Mar 10 – Mar 24direct sow, 2–4 weeks before last frost | half-hardy |
| Carrots | — | Mar 17 – Mar 24direct sow, 2–3 weeks before last frost | half-hardy |
| Tomatoes | Feb 10 – Feb 24 | Apr 14 – Apr 21transplant, 1–2 weeks after last frost | tender |
| Basil | Feb 10 – Feb 24 | Apr 14 – Apr 28transplant, 1–3 weeks after last frost | tender |
| Peppers | Jan 27 – Feb 10 | Apr 21 – Apr 28transplant, 2–3 weeks after last frost | tender |
| Eggplant | Jan 27 – Feb 10 | Apr 21 – Apr 28transplant, 2–3 weeks after last frost | tender |
| Green beans | — | Apr 14 – Apr 28direct sow, 1–3 weeks after last frost | tender |
| Sweet corn | — | Apr 14 – Apr 28direct sow, 1–3 weeks after last frost | tender |
| Cucumbers | Mar 10 – Mar 17 | Apr 14 – Apr 28transplant, 1–3 weeks after last frost | tender |
| Squash & zucchini | Mar 10 – Mar 17 | Apr 14 – Apr 28transplant, 1–3 weeks after last frost | tender |
| Watermelon | Mar 10 – Mar 17 | Apr 21 – Apr 28transplant, 2–3 weeks after last frost | tender |
Dates for Wilmington (last frost Apr 7, NOAA station Wilmington Porter Rsch, DE, 4 miles from ZIP 19801). General rules of thumb; wait for soil near 50 °F for most seeds and 60 °F for beans, corn and squash.
How Long Is the Growing Season in Delaware?
The frost-free growing season in Delaware lasts about 200 to 222 days for most ZIP codes, with a median of 209 days. Among the listed cities, Milford has the shortest season at 200 days and Millsboro the longest at 217.
Season length decides which varieties ripen: compare it with the “days to maturity” on seed packets, counted from transplanting for tomatoes and peppers. NOAA stations in Delaware range from 200 days at Greenwood 2 NE, DE to 231 days at Lewes, DE. Planning beds before the season starts helps in short seasons — a plant spacing calculator for vegetable beds shows how many transplants fit.
What Hardiness Zones Are in Delaware?
Delaware spans USDA hardiness zones 7a to 8a, with zone 7b the most common. Zones describe winter cold and decide which perennials survive, while frost dates set when to plant annual vegetables and flowers.
The Delaware planting zone map with the zone of each city shows how the zones are spread across the state and which plants are hardy in all of them.
Frequently Asked Questions
- When is the last frost in Delaware?
- The average last spring frost in Delaware falls between April 2 and April 11 for most ZIP codes, with a statewide median of April 7. Among major cities it ranges from April 4 in Dover to April 11 in Seaford.
- When is the last frost in Wilmington, Delaware?
- Wilmington's average last spring frost is April 7, and by April 24 the chance of a later frost drops to 10%. Its first fall frost averages November 4, giving a 209-day growing season (NOAA station Wilmington Porter Rsch, DE).
- When should you plant tomatoes in Delaware?
- Transplant tomatoes in Delaware 1 to 2 weeks after the local average last frost, once nights stay above about 50 °F: Apr 14 – Apr 21 in Wilmington, Apr 11 – Apr 18 in Dover and Apr 14 – Apr 21 in Newark. Start seeds indoors 6 to 8 weeks before the last frost.
- When is the first frost in Delaware?
- The average first fall frost in Delaware arrives between October 30 and November 10 for most ZIP codes, with a median of November 4. Harvest tender crops such as tomatoes, peppers and basil before then or cover them on cold nights.
- How long is the growing season in Delaware?
- The frost-free growing season in Delaware lasts about 200 to 222 days for most ZIP codes, with a median of 209 days, from 200 days in Milford to 217 days in Millsboro.
Frost data: NOAA National Centers for Environmental Information, 1991–2020 U.S. Climate Normals (32 °F freeze dates by probability). ZIP code and city locations and populations: U.S. Census Bureau Gazetteer files and Vintage 2024 population estimates. Planting windows are general rules of thumb. PlantoScan is not affiliated with or endorsed by these agencies.