| City | Population | Last spring frost | First fall frost | Growing season | Zone |
|---|---|---|---|---|---|
| Wilmington | 73,512 | Apr 7 | Nov 4 | 209 days | 7b |
| Dover | 40,592 | Apr 4 | Nov 4 | 214 days | 7b |
| Newark | 30,359 | Apr 7 | Nov 2 | 208 days | 7b |
| Middletown | 25,798 | Apr 7 | Nov 2 | 208 days | 7b |
| Milford | 14,723 | Apr 11 | Oct 30 | 200 days | 7b |
| Smyrna | 13,340 | Apr 4 | Nov 4 | 214 days | 7b |
| Seaford | 9,165 | Apr 11 | Oct 30 | 200 days | 7b |
| Georgetown | 8,291 | Apr 4 | Nov 6 | 217 days | 7b |
| Millsboro | 7,890 | Apr 4 | Nov 6 | 217 days | 7b |
| Elsmere | 6,196 | Apr 7 | Nov 4 | 209 days | 7b |
| New Castle | 5,726 | Apr 7 | Nov 1 | 209 days | 7b |