Portland, OR Frost Dates
Average frost dates, USDA hardiness zone, and growing season length for Portland, Oregon.
Gardening in Portland
Portland's gardening culture is as earnest and committed as the city itself. This is a place where people keep backyard chickens, grow heirloom tomatoes they can name by cultivar, and get genuinely excited about cover crop rotations. The city's foodie reputation started in backyards before it ever reached restaurant kitchens.
The Willamette Valley's climate is Pacific Northwest perfection for cool-season crops — mild, moist, and moderate. Your kale, lettuce, and peas grow for months without bolting. The catch is summer: Portland does get genuinely hot (90°F+) for a few weeks, and the dry July-September period means irrigation is essential. The gardening joke in Portland is that anyone can grow lettuce, but growing a ripe tomato earns you a merit badge.
Timbers fans bring the same passion to their garden beds that they bring to Providence Park. Portland's community garden waiting lists are legendary — some neighborhoods have multi-year waits. The city's seed library movement, tool-sharing cooperatives, and plant swap events are peak Portland: collaborative, sustainable, and slightly competitive about who grew the weirdest heirloom variety.
What This Means for Portland Gardeners
The average last spring frost in Portland is around March 10, and the average first fall frost arrives around November 10. That gives you approximately 245 frost-free days to work with.
That's a generous season. You have time for full-size tomatoes, long-season peppers, and even watermelons without the anxiety of racing the frost. Start warm-season seeds indoors 6-8 weeks before your last frost to hit the ground running. Fall planting is your second opportunity — garlic, kale, lettuce, and broccoli all go in 8-10 weeks before your first frost for harvest into late autumn.
These dates are based on NOAA 30-year Climate Normal data for the Portland area. Your actual frost dates could shift 2-3 weeks in either direction in any given year. Learn more about our data sources.
What to Grow in Portland
Portland's 245-day growing season is generous — long enough for two full growing windows (spring and fall) with warm-season crops between them. You can grow the full range of vegetables, herbs, and flowers with proper timing. Focus on heat-tolerant varieties for midsummer and cool-season crops for extended fall harvests. Recommended starting points: tomatoes, peppers, beans, cucumbers, squash, garlic, kale, and sunflowers.
See the full Oregon planting guide for all 40 plants: Oregon Planting Calendar. Or enter your zip code for exact planting dates personalized to Portland.
More About Zone 8B
Portland is in USDA Hardiness Zone 8B, which means average annual extreme minimum temperatures between 15°F to 20°F. View the full Zone 8B planting guide.
See the complete planting calendar for Oregon: Oregon Planting Calendar.
Other Cities in Oregon
Frequently Asked Questions
These dates are based on NOAA's 30-year Climate Normal data for the Portland area. They represent historical averages, not predictions. In any given year, the actual last frost could be 2-3 weeks earlier or later. Microclimates within Portland (urban heat islands, hilltops, low-lying valleys) can also shift your local frost dates by a week or more.
Cool-season crops go in 3-4 weeks before your last frost (March 10). Warm-season crops wait until 2 weeks after. You have time for a fall round too — plant cool-season crops again in late summer for harvest into autumn. Enter your zip code for exact dates.