Planting Guides
When to Plant Lettuce in San Francisco: Complete Guide + Best Varieties for Zone 10a
San Francisco, California
USDA Zone 10a
Last Frost: Jan 15
Last updated: October 30, 2025
Learn when to plant lettuce in San Francisco with specific dates for Zone 10a. Compare 6 varieties and discover why the Bay Area's fog-cooled Mediterranean climate makes San Francisco the only major US city where lettuce grows year-round with zero summer gap.
— Image © PlantReference.org 2026
Quick Answer
Plant lettuce year-round in San Francisco. No summer gap exists in fog-belt neighborhoods. Sow every 10-14 days any month for continuous harvest.
TL;DR
Plant lettuce every month of the year in San Francisco. The Bay Area's fog-cooled Mediterranean climate creates the only major US city with zero summer gap—summer highs average just 65-72°F in fog-belt neighborhoods, well below the 80°F bolting threshold. The 334-day frost-free season and rare freezes make genuine 12-month production feasible without any season extension infrastructure. Lactuca sativa 'Buttercrunch' leads year-round, and even heat-sensitive Lactuca sativa var. capitata (Iceberg) produces through San Francisco's cool summer. The primary challenge isn't heat or cold—it's the fog-driven microclimate variation between neighborhoods.
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Frequently Asked Questions
When is the best time to plant lettuce in San Francisco?
Every month. San Francisco is the only major US city where lettuce can be planted year-round with zero summer gap in fog-belt neighborhoods (Sunset, Richmond, Outer Parkside). Succession sow every 10-14 days any month for continuous harvest. No seasonal planning required—lettuce is always in season. Warmer neighborhoods (Mission, Potrero Hill) may experience a brief 2-3 week warm period in September-October but this barely qualifies as a gap compared to the 6-12 week gaps other cities face.
What makes San Francisco unique for lettuce?
The fog. San Francisco's famous marine layer keeps summer temperatures at 60-72°F in western neighborhoods—cooler than most American cities' spring temperatures. This eliminates the bolting response that creates mandatory summer gaps everywhere else. San Francisco is the only major US city in Zone 10a where lettuce grows through summer, because every other Zone 10a city (Phoenix, Miami, LA) is far too hot. The fog completely inverts the normal Zone 10a growing calendar for cool-season crops.
How do San Francisco's microclimates affect lettuce?
Dramatically. The fog creates a 15-20°F temperature gradient across the city during summer. Fog-belt neighborhoods (Sunset, Richmond, Outer Parkside) average 60-65°F in July-August—perfect for year-round lettuce with zero interruption. Warm neighborhoods (Mission, Potrero Hill, Bernal Heights) regularly reach 80°F+ and experience brief September-October heat events that can trigger bolting. Understanding your specific neighborhood's fog exposure is the single most important factor in San Francisco lettuce planning.
Can I grow Iceberg lettuce in San Francisco?
Yes—San Francisco is arguably the only city in America where home gardeners can reliably grow Lactuca sativa var. capitata (Iceberg) through summer. The fog-cooled 65-72°F temperatures in western neighborhoods eliminate the tipburn and premature bolting that make Iceberg the most challenging lettuce type everywhere else. Plant Iceberg in fog-belt neighborhoods for the best results. Warmer eastern neighborhoods should time Iceberg for the traditional November-March cool season.
What's the main challenge for San Francisco lettuce?
Not heat—wind and sandy soil. San Francisco's afternoon ocean winds, especially in western neighborhoods, can damage delicate lettuce leaves and accelerate moisture loss. The city's sandy soils drain quickly but retain almost no nutrients, requiring heavier compost amendment (3-4 inches) and more frequent feeding (every 2-3 weeks) than most cities. Aphids are the primary pest in the dry climate, but downy mildew is virtually nonexistent—a genuine advantage over humid cities.
How does San Francisco compare to Seattle and Portland for lettuce?
All three are elite lettuce cities, but San Francisco is the only one with zero summer gap. Seattle has a 3-4 week gap, Portland 4-5 weeks—both still need cloches for winter rain protection. San Francisco needs neither shade cloth for summer nor cloches for winter, making it the lowest-maintenance lettuce city in America. The trade-off is San Francisco's sandy soil requiring heavier amendment and its wind exposure requiring protection in western neighborhoods. Seattle and Portland have superior natural soil and no wind issues but face slug pressure that San Francisco's dry climate completely avoids.
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Written By
D
David Kim
David is a software engineer who got into gardening after buying a fixer-upper in the Sunset District with a neglected backyard. San Francisco's microclimates fascinated him—he quickly learned that what grows three blocks away might not work in his fog belt yard. David now maintains a productive vegetable garden despite the marine layer, growing cool-season crops almost year-round and experimenting with season extension techniques. He volunteers at a local community garden and writes about urban food growing, microclimate gardening, and the particular challenges of Bay Area conditions. His approach is methodical—he keeps detailed notes and isn't afraid to share what didn't work.
