Frost dates for 19897Wilmington, 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 19897 is matched to the NOAA station Wilmington New Castle Co Ap, DE, 12 km away, at 79 ft elevation (69 ft higher 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 |
| Newark Ag Farm, DE | 106 ft | Apr 7 | Nov 2 |
| Wilmington Porter Rsch, DE | 270 ft | Apr 7 | Nov 4 |
| Marcus Hook, PA | 10 ft | Mar 30 | Nov 16 |
Frost dates near Wilmington
- Newark, DE 19712 · last Apr 7, first Nov 1
- New Castle, DE 19721 · last Apr 7, first Nov 1
- Wilmington, DE 19850 · last Apr 7, first Nov 1
- Delaware City, DE 19706 · last Apr 7, first Nov 1
- Saint Georges, DE 19733 · last Apr 7, first Nov 1
- Port Penn, DE 19731 · last Apr 7, first Nov 1
- Kirkwood, DE 19708 · last Apr 7, first Nov 2
- Bear, DE 19701 · last Apr 7, first Nov 1
Frequently asked questions
- When is the last frost in Wilmington, DE?
- For ZIP code 19897, 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 19897?
- 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.