Portland, Maine: freeze dates & growing season
Three different things get called “Portland” here, so this page is explicit about all three: the metro label (Portland), the anchor geography (Census ZCTA 04101, a downtown ZIP-code area), and the climate record (the NOAA station below). Windows are calculated from the station — not from your street address.
Climate basis: NOAA station Portland INTL Jetport, ME (USW00014764), 2 mi (4 km) from the ZCTA 04101 centroid, elevation 45 ft, on the 1991–2020 climate normals.Last spring freezeApril 261-in-10 after May 7
First fall freezeOctober 151-in-10 before Oct 2
Frost-free season≈ 170 daysmedian at 32°F
Hard freeze, 28°Apr 14 – Oct 27kills even hardy greens
USDA zone6a-10 to -5°F winter low — not frost timing
The year
- indoors under lights
- in the garden
- frost-free season
- 1-in-10 years still freeze to May 7
What that means in practice
- Tomatoes: plant May 3 – May 17
- Peas: plant March 15 – March 29
- Garlic: plant cloves October 22 – October 29
All 79 crops in Portland
- Arugula
- Asparagus
- Basil
- Beets
- Bok choy
- Borage
- Broccoli
- Brussels sprouts
- Bulb Fennel
- Cabbage
- Calendula
- Carrots
- Cauliflower
- Celeriac
- Celery
- Celosia
- Swiss chard
- Chinese Cabbage (Napa)
- Chives
- Cilantro
- Collards
- Cosmos
- Cucumbers
- Dill
- Eggplant
- Endive and Escarole
- Garden Cress
- Garlic
- Green beans
- Hairy Vetch
- Horseradish
- Kale
- Kohlrabi
- Lavender
- Leeks
- Lemon Balm
- Lettuce
- Lima Bean
- Marigold
- Melons & cantaloupe
- Morning glory
- Mustard greens
- Nasturtium
- Okra
- Onions
- Parsley
- Parsnips
- Peanut
- Peas
- Peppers
- Potatoes
- Pumpkins
- Radicchio
- Radishes
- Rhubarb
- Rosemary
- Rutabaga
- Sage
- Salsify
- Scallions (Green Onions)
- Snapdragon
- Southern Pea
- Spinach
- Strawberries
- Summer Savory
- Summer squash & zucchini
- Sunflower
- Sweet Alyssum
- Sweet corn
- Sweet Marjoram
- Sweet potatoes
- Tarragon
- Thyme
- Tomatoes
- Turnips
- Watermelon
- Winter Rye
- Winter squash
- Zinnia
These windows describe typical years (1991–2020 climate normals), not this year's forecast. Freezes happen outside them — especially in frost pockets, valleys, and urban edges. Watch the forecast before committing tender plants.
Check a specific ZIP instead
Metro climates vary — elevation, water, and urban heat shift freeze dates by days to weeks. Look up your exact ZIP:
Nearby reviewed metros
Manchester, NH · Boston, MA · Providence, RI · Burlington, VT · Hartford, CT