Santa Rosa, CA Frost Dates
Average frost dates, USDA hardiness zone, and growing season length for Santa Rosa, California.
Gardening in Santa Rosa
Sonoma County's seat sits in wine country, where the same climate that grows world-class Pinot Noir grows world-class vegetables, herbs, and fruit.
Zone 9a with Sonoma Valley warmth. Your 259-day growing season benefits from the valley's heat accumulation. Morning fog burns off to warm afternoons — the classic Sonoma pattern that grapes and garden plants both love.
Sonoma County's farm-to-table culture isn't marketing — it's the foundation of the local economy. Home gardeners benefit from the same knowledge base that supports commercial wine grape, apple, and specialty crop production.
What This Means for Santa Rosa Gardeners
The average last spring frost in Santa Rosa is around March 1, and the average first fall frost arrives around November 15. That gives you approximately 259 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 Santa Rosa 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 Santa Rosa
Santa Rosa's 259-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 California planting guide for all 40 plants: California Planting Calendar. Or enter your zip code for exact planting dates personalized to Santa Rosa.
More About Zone 9A
Santa Rosa is in USDA Hardiness Zone 9A, which means average annual extreme minimum temperatures between 20°F to 25°F. View the full Zone 9A planting guide.
See the complete planting calendar for California: California Planting Calendar.
Other Cities in California
Frequently Asked Questions
These dates are based on NOAA's 30-year Climate Normal data for the Santa Rosa 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 Santa Rosa (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 1). 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.