Frost dates for 19805Wilmington, DE
The average last spring frost in Wilmington is April 7 and the average first fall frost is November 1, giving a typical growing season of about 209 days. Dates are based on NOAA 1991-2020 climate normals.
- Average last spring frost
- Apr 7
- Average first fall frost
- Nov 1
- Growing season
- 209 days
Safer after Apr 21 (1-in-10 risk)
Possible by Oct 19 (1-in-10 risk)
Last frost typically in 155 days
Frost risk by date
NOAA reports frost dates as probabilities. The middle date is the average (a 50% chance). For spring, the 10% date is a safer planting date: frost after it happens in about 1 year in 10. Light frost (36°F) can damage tender plants; a hard freeze (28°F) kills most annuals.
| Temperature | Last spring: 90% / 50% / 10% chance | First fall: 10% / 50% / 90% chance | Growing season (50%) | Years with at least one |
|---|---|---|---|---|
| Light frost (36°F) | Apr 7 · Apr 21 · May 7 | Oct 8 · Oct 22 · Nov 3 | 183 days | 100% |
| Frost / freeze (32°F) | Mar 26 · Apr 7 · Apr 21 | Oct 19 · Nov 1 · Nov 15 | 209 days | 100% |
| Hard freeze (28°F) | Mar 11 · Mar 27 · Apr 9 | Nov 1 · Nov 14 · Dec 1 | 234 days | 100% |
Planting calendar for Wilmington
Planting windows from the University of Maryland Extension calendar, shifted to your average frost dates. Use them as a starting point and adjust for seed packet instructions and local conditions.
| Crop | Task | Window |
|---|---|---|
| Tomatoes | Start seeds indoors | Mar 7 – May 13 |
| Tomatoes | Transplant outdoors | Apr 23 – Jul 12 |
| Peppers | Start seeds indoors | Mar 7 – Apr 7 |
| Peppers | Transplant outdoors | May 7 – Jun 7 |
| Eggplant | Start seeds indoors | Mar 24 – Apr 22 |
| Eggplant | Transplant outdoors | May 7 – Jun 7 |
| Cucumbers | Sow outdoors | May 7 – Jul 22 |
| Summer squash | Sow outdoors | Apr 23 – Jun 7 |
| Winter squash & pumpkins | Sow outdoors | May 7 – Jun 7 |
| Snap beans | Sow outdoors | Apr 23 – Aug 14 |
| Sweet corn | Sow outdoors | Apr 23 – Jul 12 |
| Watermelon & cantaloupe | Sow outdoors | May 7 – Jun 7 |
| Okra | Sow outdoors | Apr 30 – May 23 |
| Peas | Sow outdoors (spring) | Mar 7 – Apr 22 |
| Potatoes | Plant outdoors (spring) | Mar 7 – May 7 |
| Onions | Start seeds indoors (spring) | Jan 24 – Feb 20 |
| Onions | Transplant outdoors (spring) | Mar 24 – Apr 22 |
| Broccoli | Start seeds indoors (spring) | Feb 17 – Mar 23 |
| Broccoli | Transplant outdoors (spring) | Mar 24 – Apr 22 |
| Broccoli | Start seeds indoors (fall) | Jul 2 – Jul 12 |
| Broccoli | Transplant outdoors (fall) | Aug 1 – Aug 12 |
| Cabbage | Start seeds indoors (spring) | Feb 7 – Mar 7 |
| Cabbage | Transplant outdoors (spring) | Mar 7 – Apr 7 |
| Cabbage | Start seeds indoors (fall) | Jun 22 – Jul 22 |
| Cabbage | Transplant outdoors (fall) | Jul 22 – Aug 22 |
| Leaf lettuce | Sow outdoors (spring) | Mar 7 – May 23 |
| Leaf lettuce | Sow outdoors (fall) | Jul 22 – Sep 7 |
| Spinach | Sow outdoors (spring) | Feb 28 – Apr 13 |
| Spinach | Sow outdoors (fall) | Aug 8 – Sep 12 |
| Radishes | Sow outdoors (spring) | Mar 7 – Apr 27 |
| Radishes | Sow outdoors (fall) | Jul 22 – Sep 22 |
| Kale | Sow outdoors (spring) | Mar 24 – Apr 13 |
| Kale | Sow outdoors (fall) | Jul 15 – Aug 22 |
| Carrots | Sow outdoors (spring) | Apr 7 – May 23 |
| Carrots | Sow outdoors (fall) | Jun 22 – Aug 7 |
| Garlic | Plant outdoors (fall) | Oct 22 – Nov 22 |
Where these dates come from
ZIP code 19805 is matched to the NOAA station Wilmington New Castle Co Ap, DE, 8 km away, at 79 ft elevation (29 ft lower than the ZIP code's center). Nearby stations for comparison:
| Station | Elevation | Avg last frost | Avg first frost |
|---|---|---|---|
| Wilmington New Castle Co Ap, DE (used) | 79 ft | Apr 7 | Nov 1 |
| Wilmington Porter Rsch, DE | 270 ft | Apr 7 | Nov 4 |
| Marcus Hook, PA | 10 ft | Mar 30 | Nov 16 |
| Newark Ag Farm, DE | 106 ft | Apr 7 | Nov 2 |
Frost dates near Wilmington
- Wilmington, DE 19806 · last Apr 7, first Nov 4
- Montchanin, DE 19710 · last Apr 7, first Nov 4
- Rockland, DE 19732 · last Apr 7, first Nov 4
- Winterthur, DE 19735 · last Apr 7, first Nov 4
- New Castle, DE 19726 · last Apr 7, first Nov 1
- Hockessin, DE 19707 · last Apr 7, first Nov 4
- Deepwater, NJ 08023 · last Apr 7, first Nov 1
- Yorklyn, DE 19736 · last Apr 7, first Nov 4
Frequently asked questions
- When is the last frost in Wilmington, DE?
- For ZIP code 19805, the average last spring frost (32°F) is April 7, based on NOAA 1991-2020 climate normals for the Wilmington New Castle Co Ap, DE weather station. There is a 1-in-10 chance of a frost after April 21.
- When is the first frost in Wilmington, DE?
- The average first fall frost (32°F) is November 1. There is a 1-in-10 chance of frost by October 19, so tender plants are at risk from that point on.
- How long is the growing season in 19805?
- In half of years, the frost-free season (between the last and first 32°F frost) is at least 209 days long.
- Are these frost dates a forecast?
- No. They are 30-year averages and probabilities from NOAA weather station records. Use them to plan, then watch your local forecast before planting tender crops or leaving them uncovered.