What Planting Zones Are in Delaware?
Delaware spans USDA hardiness zones 7a to 8a, where the average coldest winter night ranges from 0 °F to 15 °F (−17.8 °C to −9.4 °C). Zone 7b covers the most ZIP codes, 95%, and zone 7b together cover 95% of the state.
Bars show each zone's share of the 93 Delaware ZIP codes in the official 2023 USDA ZIP code table; select a zone for its temperatures and hardy plants.
What Hardiness Zone Are Delaware Cities In?
Wilmington is in zone 7b, Dover is in zone 7b, Newark is in zone 7b and Middletown is in zone 7b. The table lists the zone, winter low and average frost dates for 11 Delaware cities, using the ZIP code nearest each city center.
| City | ZIP | Zone | Winter low | Last frost | First frost |
|---|---|---|---|---|---|
| Wilmington | 19801 | 7b | 5 °F to 10 °F | Apr 7 | Nov 4 |
| Dover | 19901 | 7b | 5 °F to 10 °F | Apr 4 | Nov 4 |
| Newark | 19717 | 7b | 5 °F to 10 °F | Apr 7 | Nov 2 |
| Middletown | 19730 | 7b | 5 °F to 10 °F | Apr 7 | Nov 1 |
| Milford | 19963 | 7b | 5 °F to 10 °F | Apr 11 | Oct 30 |
| Smyrna | 19977 | 7b | 5 °F to 10 °F | Apr 4 | Nov 4 |
| Seaford | 19973 | 7b | 5 °F to 10 °F | Apr 11 | Oct 30 |
| Georgetown | 19947 | 7b | 5 °F to 10 °F | Apr 4 | Nov 6 |
| Millsboro | 19966 | 7b | 5 °F to 10 °F | Apr 4 | Nov 6 |
| Elsmere | 19805 | 7b | 5 °F to 10 °F | Apr 7 | Nov 4 |
| Fenwick Island | 19944 | 8a | 10 °F to 15 °F | Apr 7 | Nov 2 |
Zone: 2023 USDA ZIP code table for the ZIP code nearest each city's Census center point. Frost dates: 50% (median) dates from the nearest NOAA station, 1991–2020 normals. Cities: the largest Delaware places by 2024 Census population estimates, spread across the state, plus the largest place in each common zone. Large cities can span two half zones.
Which Parts of Delaware Are in Each Zone?
Zone 7b, the coldest Delaware zone with towns, covers 95% of ZIP codes around Wilmington, Dover and Newark. Zone 8a, the warmest, covers 4% around Rehoboth Beach and Bethany Beach. The table lists the largest places in every zone.
| Zone | Avg. coldest night | Share of ZIPs | Largest places in this zone |
|---|---|---|---|
| Zone 7a | 0 °F to 5 °F | 1% (1) | Rural ZIP codes only |
| Zone 7b | 5 °F to 10 °F | 95% (88) | Wilmington, Dover, Newark, Middletown |
| Zone 8a | 10 °F to 15 °F | 4% (4) | Rehoboth Beach, Bethany Beach |
Places: incorporated places with 1,000+ residents, assigned the zone of the ZIP code nearest their Census center point.
What Do the Hardiness Zones Mean for Delaware Gardeners?
A Delaware gardener in zone 8a sees winter lows about 10 °F milder than one in zone 7a, so a shrub or perennial that thrives in one part of the state can die in another. Choose plants rated to your own ZIP code's zone or colder.
Hardiness zones follow latitude, elevation and large bodies of water rather than state lines. Higher ground and inland valleys that trap cold air usually sit in colder half zones, while cities, coasts and large lakes moderate winter lows. Within Delaware, a plant labelled “zones 7–8” survives winter in at least 95% of ZIP codes, but plants at the edge of their range benefit from mulch and a sheltered spot. Enter a ZIP code in the USDA hardiness zone finder by ZIP code to check your exact half zone before buying perennials.
A zone describes winter cold only. Summer heat, humidity, rainfall and soil decide whether a cold-hardy plant thrives, and planting dates for vegetables follow frost dates, not zones: two Delaware towns in the same zone can have last frosts weeks apart.
What Plants Grow Well Across Delaware?
248 plants in PlantoScan's catalogue are hardy in every zone from 7b to 7b, the zones that cover 95% of Delaware ZIP codes. Popular examples include hydrangea, peony and daisy.
Hydrangea
Hydrangea macrophylla
Zone 5 – 9
AI generated
Peony
Paeonia lactiflora
Zone 3 – 8
AI generated
- DaisyBellis perennisPlantoScan
Daisy
Bellis perennis
Zone 4a – 8b
Chrysanthemum
Chrysanthemum morifolium
Zone 5a – 9b
PlantoscanAI generated
Poppy
Papaver somniferum
Zone 3a – 9b
AI generated
Carnation
Dianthus caryophyllus
Zone 5a – 9b
AI generated
Daffodil
Narcissus poeticus
Zone 3 – 8
AI generated
Azalea
Azalea indica
Zone 6a – 9b
AI generated
Arugula
Eruca sativa
Zone 5a – 10b
AI generated
Hardiness ranges come from PlantoScan's plant database; gardeners in Delaware's colder or warmer edge zones should check each plant's full range.
When Is the Last Frost in Delaware?
Across most Delaware ZIP codes, the average last spring frost falls between April 2 and April 11, from April 4 in Dover to April 11 in Seaford. Tender vegetables such as tomatoes go out 1 to 2 weeks after the local date.
The last and first frost dates for Delaware cities include the safer 90% planting date, the fall frost date, growing season length and a tomato planting table for each city.
Frequently Asked Questions
- What planting zone is Delaware?
- Delaware spans USDA hardiness zones 7a to 8a on the 2023 USDA Plant Hardiness Zone Map. Zone 7b is the most common, covering 95% of the state's 93 ZIP codes, and zone 7b together cover 95%.
- What hardiness zone is Wilmington, Delaware?
- Wilmington is in USDA hardiness zone 7b (ZIP 19801), where the average coldest winter night reaches 5 °F to 10 °F. Its average last spring frost is April 7 and its first fall frost November 4.
- What hardiness zone is Dover, Delaware?
- Dover is in USDA hardiness zone 7b (ZIP 19901), where the average coldest winter night reaches 5 °F to 10 °F. Its average last spring frost is April 4 and its first fall frost November 4.
- What hardiness zone is Newark, Delaware?
- Newark is in USDA hardiness zone 7b (ZIP 19717), where the average coldest winter night reaches 5 °F to 10 °F. Its average last spring frost is April 7 and its first fall frost November 2.
- What is the coldest hardiness zone in Delaware?
- Zone 7a (0 °F to 5 °F) is the coldest zone in Delaware, found in 1 ZIP code. The warmest is zone 8a (10 °F to 15 °F), around Rehoboth Beach and Bethany Beach.
Zones: 2023 USDA Plant Hardiness Zone Map ZIP code table, USDA Agricultural Research Service and the PRISM Climate Group, Oregon State University, used without changes. Frost dates: NOAA National Centers for Environmental Information, 1991–2020 U.S. Climate Normals. City locations and populations: U.S. Census Bureau Gazetteer files and Vintage 2024 population estimates. PlantoScan is not affiliated with or endorsed by these agencies.