The 3 planting zones in Portland, Maine are zone 5b, zone 6a, and zone 6b, according to latest 2023 USDA data. The 3 planting zones in Portland, Maine are listed below.
- Zone 5b: Zone 5b has minimum temperatures ranging from -26.1°C to -23.3°C (-15°F to -10°F) and includes the northwestern edge of Portland, bordering Westbrook and other inland areas. Zone 5b represents the coldest growing conditions in Portland, covering less densely populated outer regions.
- Zone 6a: Zone 6a has minimum temperatures ranging from -23.3°C to -20.6°C (-10°F to -5°F) and includes most of Portland’s neighborhoods such as the Arts District, Back Cove, Downtown, and Peaks Island.
- Zone 6b: Zone 6b has minimum temperatures ranging from -20.6°C to -17.8°C (-5°F to 0°F) and includes the southeastern coastal areas of Portland, particularly portions extending toward Scarborough and some coastal peninsulas.
Locate your Portland, Maine, USDA zone using our three tools given below, zipcode to planting zone search tool, interactive map, or planting zone table.
Portland (ME) Planting Zones by ZipCode
Enter your Portland (ME) 5 digit Zip-code to find its USDA Planting Zone.
Portland (ME) Planting Zones Map
Select or type your Portland (ME) in the search box below to find its USDA Growing Zone.
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Portland Area Planting Zone
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Portland (ME) Planting Zones Table
Below given table lists all the Portland (ME) locations with their USDA Hardiness Zones.
| Portland Location | Planting Zone |
|---|---|
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Portland (ME) Growing Zones
The 3 planting zones in Portland, Maine are zone 5b, zone 6a, and zone 6b.
Zone 5b
Zone 5b(-26.1°C to -23.3°C / -15°F to -10°F) includes the northwestern edge of Portland and represents the coldest growing conditions in Portland. This zone supports hardy perennials like Coneflowers (Echinacea purpurea), Delphiniums (Delphinium spp.), and Peonies (Paeonia lactiflora).
Zone 6a
Zone 6a (-23.3°C to -20.6°C / -10°F to -5°F) includes most of Portland’s neighborhoods and dominates Portland’s landscape. This zone is suitable for growing vegetables like Tomatoes (Solanum lycopersicum), Peppers (Capsicum annuum), and Basil (Ocimum basilicum).
Zone 6b
Zone 6b (-20.6°C to -17.8°C / -5°F to 0°F) includes the southeastern coastal areas of Portland, particularly portions extending toward Scarborough. Zone 6b here, benefits from ocean buffering effects, creating slightly milder winter conditions than the rest of Portland. This zone is ideal for growing ornamental plants like Clematis (Clematis spp.), Honeysuckle (Lonicera spp.), and Coneflowers (Echinacea purpurea).