Planting Guides
When to Plant Kale in Portland: Complete Guide + Best Varieties for Zone 8b
Portland, Oregon
USDA Zone 8b
Last Frost: Mar 20
Last updated: October 30, 2025
Plant kale in Portland August-October for winter harvest, or March-May for summer crops. Zone 8b's mild climate allows year-round kale growing with proper timing.
— Image © PlantReference.org 2026
Quick Answer
Plant kale in Portland August 15-October 1 for winter harvest or March 15-May 1 for summer crops. Fall plantings taste sweeter after frost exposure.
TL;DR
Portland's Zone 8b climate is perfect for kale. Plant fall crops August 15-October 1 for winter harvest, or spring crops March 15-May 1 for summer production. The mild Pacific Northwest weather allows nearly year-round growing with varieties like Brassica oleracea 'Winterbor' and Brassica oleracea 'Lacinato' surviving winter outdoors. Fall plantings produce the sweetest kale after frost exposure.
Frequently Asked Questions
When is the best time to plant kale in Portland for maximum flavor?
Plant kale in Portland between August 15-September 15 for the best flavor. Fall-planted kale matures during cool autumn weather and benefits from our November frost, which converts starches to sugars and creates the sweetest, most tender leaves. These plants continue producing excellent harvests throughout Portland's mild winter, providing fresh kale from October through April. Spring plantings work but lack the flavor enhancement that frost provides.
Can I grow kale year-round in Portland's Zone 8b climate?
Yes, Portland's Zone 8b climate allows nearly year-round kale production with proper variety selection and timing. Plant cold-hardy varieties like Brassica oleracea 'Winterbor' or Brassica oleracea 'Lacinato' in fall for winter harvest, then follow with spring plantings of Brassica oleracea 'Red Russian' for summer harvest. Use succession planting every 2-3 weeks and provide summer shade during heat waves. Winter protection with lightweight row covers ensures continuous harvest even during Portland's coldest periods.
Which kale varieties handle Portland's wet winters best?
Brassica oleracea 'Winterbor' and Brassica oleracea 'Redbor' handle Portland's wet winters exceptionally well. These curly varieties shed water better than flat-leaved types, preventing fungal diseases common during our extended rainy periods. Brassica oleracea 'Lacinato' also performs well due to its upright growth habit and waxy leaf surface. Avoid Brassica oleracea 'Red Russian' for winter growing as its flat leaves collect moisture and are more susceptible to rot during Portland's wet season.
How do I prevent slug damage on my Portland kale plants?
Prevent slug damage through integrated management: Apply iron phosphate slug bait around plants at first planting and reapply after rain. Create barriers using copper tape around raised beds or diatomaceous earth rings around individual plants. Maintain clean cultivation by removing plant debris, fallen leaves, and weeds where slugs hide. Water in morning rather than evening to reduce nighttime moisture when slugs are most active. Install beer traps or overturned grapefruit halves as monitoring tools to track slug populations.
Should I use row covers for kale in Portland winters?
Row covers benefit Portland kale during extreme cold spells below 20°F (-6°C) but aren't necessary for normal winter weather. Portland's mild Zone 8b winters rarely damage established kale plants. Use lightweight row covers (0.5-1 oz fabric) during ice storms or when temperatures drop below 15°F (-9°C) for more than 24 hours. Remove covers during warm periods to prevent overheating and ensure good air circulation. Row covers are more important for pest protection during spring plantings to exclude cabbage root maggot flies.
When should I stop planting kale for winter harvest in Portland?
Stop planting kale for winter harvest by October 1 in Portland. Later plantings won't have sufficient time to develop before decreasing daylight and cool temperatures slow growth dramatically. Plants need at least 60-75 days to reach harvestable size, and October plantings may only produce baby leaves before winter dormancy begins. For continuous winter harvest, make your final planting by September 15 to ensure full-sized plants before the November 9 average first frost date.
How often should I water kale during Portland's dry summer months?
Water Portland kale 1-2 times weekly during summer months (July-September), applying 1-2 inches (2.5-5 cm) total per week. Check soil moisture 2-3 inches (5-7 cm) deep; water when soil feels dry at this depth. Use drip irrigation or soaker hoses to maintain consistent moisture without wetting leaves, which can promote fungal diseases. Mulch around plants with 2-3 inches (5-7 cm) of organic matter to retain moisture and reduce watering frequency. Increase watering during heat waves above 85°F (29°C) to prevent stress and bitterness.
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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.
