Planting Guides
When to Plant Tomatoes in Portland: Complete Guide + Best Varieties for Zone 8b
Portland, Oregon
USDA Zone 8b
Last Frost: Mar 20
Last updated: December 4, 2025
Learn when to plant tomatoes in Portland with specific dates for Zone 8b. Compare 6 varieties & discover which grow best in Oregon's maritime climate.
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Quick Answer
Start tomato seeds indoors February 15-22 in Portland. Transplant outdoors April 2-9 after March 19 last frost for Zone 8b success.
TL;DR
Plant tomato seeds indoors February 15-22 in Portland for optimal Zone 8b success. Transplant outdoors April 2-9 after last frost risk passes on March 19. 'Stupice' and 'Early Girl' excel in Portland's cool maritime climate, while 'Cherokee Purple' thrives in the long 235-day growing season.
Frequently Asked Questions
When exactly should I start tomato seeds indoors in Portland?
Start tomato seeds indoors between February 15-22 for optimal Portland timing. This provides 6-8 weeks for strong seedling development before the April 2-9 transplant window. Portland's cool February indoor temperatures often require heating mats to maintain the 75-80°F (24-27°C) soil temperature needed for reliable germination.
What tomato varieties grow best in Portland's Zone 8b climate?
Solanum lycopersicum 'Stupice' and Solanum lycopersicum 'Early Girl' perform exceptionally well in Portland's maritime climate. Both varieties set fruit at cool temperatures (45-50°F nights) that persist through May in Portland. Solanum lycopersicum 'Cherokee Purple' thrives in Portland's moderate summers and long 235-day growing season, while Solanum lycopersicum 'Sungold' provides continuous cherry tomato production.
How do I protect tomatoes from Portland's late spring frosts?
Use Wall O Water season extenders or floating row covers for individual plant protection during cool April nights. Portland's March 19 average last frost can extend into early April in some years. Season extenders provide 10-15°F temperature protection, allowing safe April 2-9 transplanting even when overnight temperatures drop to 35-40°F.
When can I safely transplant tomatoes outside in Portland?
Transplant tomatoes April 2-9 in Portland, approximately two weeks after the March 19 average last frost date. Soil temperatures should consistently reach 55°F (13°C) before transplanting. Portland's variable spring weather makes waiting until early April safer than risking late March transplanting, even though statistical frost risk has passed.
What's the biggest challenge growing tomatoes in Portland?
Late blight disease poses the greatest threat to Portland tomatoes, thriving in our cool, moist spring and fall conditions. Prevent late blight with proper plant spacing, soil-level watering, and preventive copper fungicide applications during extended cool, wet periods. Choose resistant varieties like Solanum lycopersicum 'Early Girl' and remove infected plant material immediately.
How long is Portland's tomato growing season?
Portland enjoys a 235-day frost-free growing season from March 19 to November 9, providing excellent opportunities for both early and late-maturing varieties. This extended season allows heat-sensitive heirlooms like Solanum lycopersicum 'Brandywine' to reach full maturity while providing multiple harvests from early varieties throughout the season.
Should I grow tomatoes in containers or raised beds in Portland?
Raised beds work best in Portland due to our heavy clay soil and wet winter/spring conditions. Raised beds provide the drainage tomatoes need while warming faster in spring than ground-level plantings. If using containers, choose at least 20-gallon (76 L) sizes for indeterminate varieties and install drip irrigation to prevent the water stress that causes blossom end rot.
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Dr. Sarah Green
Sarah earned her doctorate in plant biology and spent time working in botanical garden education before transitioning to freelance writing and consulting. Now based in Portland, Oregon, she teaches plant identification workshops at local community centers and maintains a modest collection of over 60 houseplants in her small apartment. Sarah specializes in helping beginners understand plant science without the jargon—her approach focuses on practical observation over theory. She's killed her fair share of fiddle leaf figs and finally cracked the code on keeping them alive.
