When To Plant Lettuce In Northern California

Knowing when to plant lettuce in Northern California is the single most important factor for a steady, year-round harvest. Our unique climate, with its mild coastal areas, hot valleys, and snowy mountains, creates a long planting window if you time it right.

You can grow lettuce for much of the year here. The key is working around our two main challenges: the intense summer heat that makes lettuce bitter and bolt (flower), and occasional winter frosts. With a simple seasonal schedule, you’ll always have crisp leaves ready for picking.

This calendar breaks down the best planting times for our major regions. Think of it as your gardening roadmap.

Coastal Areas (San Francisco, Monterey, Marin)

Your cool, fog-friendly weather is perfect for lettuce. You have the longest season.

Spring Planting: Start seeds indoors or outdoors from January to March. Transplant from February to April.
Summer Planting: Focus on heat-tolerant varieties (like ‘Summer Crisp’) in partial shade. Plant in June for a late summer crop.
Fall Planting: This is your prime season. Sow seeds directly from mid-August through October for harvests into winter.
Winter Planting: With mild frosts, you can grow cold-hardy types (like ‘Winter Density’) under row cover from November onward.

Inland Valleys (Sacramento, San Joaquin, Napa)

Your hot summers require precise timing to avoid bolting.

Spring Planting: This is your main season. Plant as soon as soil is workable in late January or February. Get transplants in the ground by mid-March at the latest.
Summer Planting: Generally too hot. Skip it unless using shade cloth and diligent watering.
Fall Planting: Your second best season. Start seeds indoors in late August, transplant in late September/October once temps cool. You can also direct seed in October.
Winter Planting: Light frosts are common. Use cold frames or plant hardy varieties in October for early spring harvests.

Mountain & Foothill Regions (Sierra Nevada)

Your short growing season means focusing on spring and fall, with protection.

Spring Planting: Plant 2-4 weeks after your last frost date, usually late May or June. Use season extenders like cold frames.
Fall Planting: Count back 6-8 weeks from your first expected fall frost. Sow seeds in mid-to-late summer for a quick crop before the snow.

Choosing Your Lettuce Types

Matching the variety to the season is half the battle.

Leaf Lettuce (Oakleaf, Lollo Rossa): Fastest growing, best for cut-and-come-again. Good for spring and fall.
Romaine/Cos: Tolerates heat better than most. Excellent for spring planting in valleys.
Butterhead (Bibb, Boston): Prefers cooler temps. Ideal for coastal gardens and fall planting everywhere.
Crisphead (Iceberg): Requires a long, cool season. Challenging in most of NorCal; best attempted on the coast in fall.

Step-by-Step Planting Guide

Follow these steps for success everytime you sow.

1. Preparing Your Soil

Lettuce needs loose, fertile, well-draining soil. Work in 2-3 inches of compost before planting. The soil pH should be between 6.0 and 7.0. Raised beds are ideal for controlling soil quality and drainage.

2. Sowing Seeds Directly

Rake the soil smooth and create shallow rows about 1/4 inch deep.
Sow seeds sparingly, about 1 inch apart.
Cover lightly with soil and water gently with a fine spray.
Keep the soil consistently moist until seeds sprout, which takes 7-10 days.

3. Transplanting Seedlings

Harden off home-grown or store-bought seedlings for 3-5 days.
Plant them on a cloudy afternoon or in the evening.
Space plants according to variety: 6-8 inches for leaf, 10-12 inches for romaine and butterhead.
Water them in thoroughly right after planting.

4. Ongoing Care Tips

Watering: Water deeply and regularly, especially as heads form. Avoid wetting the leaves in evening to prevent disease. Mulch helps retain moisture.
Fertilizing: Use a balanced, gentle fertilizer (like fish emulsion) 2 weeks after transplanting or when direct-sown plants have 4 true leaves.
Thinning: If you direct seeded, thin seedlings to the proper spacing. The thinnings are your first tiny harvest!

Mastering the Heat: Summer Strategies

Even in hot areas, you can try for summer lettuce with these tricks.

Provide afternoon shade using a 30-40% shade cloth or plant on the east side of taller plants.
Switch to bolt-resistant varieties like ‘Jericho’ Romaine or ‘Sierra’ Batavian.
Water in the early morning to ensure plants are hydrated for the day.
Harvest leaves young and small, as they are more tender and less likely to be bitter.

Extending the Season into Winter

With a little protection, lettuce can survive cold snaps.

Use floating row covers, cold frames, or even simple cloches (like cut plastic bottles).
Choose proven winter varieties: ‘Arctic King’, ‘Rouge d’Hiver’, ‘Winter Density’.
Plant in a south-facing spot to maximize winter sun exposure.
Growth slows dramatically in winter, but leaves can still be harvested as needed.

Harvesting for Continuous Crops

How you harvest determines how long the plant produces.

Cut-and-Come-Again: For leaf lettuce, cut leaves 1-2 inches above the crown with scissors. The plant will regrow for 2-3 more harvests.
Whole Head: For head-forming types, cut the entire plant at the soil line once it feels firm.
Outer Leaves: For romaine and butterhead, you can carefully remove outer leaves as needed, allowing the center to continue growing.

Common Problems & Solutions

Stay ahead of these typical issues.

Bolting: Caused by heat and long days. Harvest early, provide shade, and switch to summer varieties.
Slugs & Snails: They love tender lettuce. Use organic bait, copper tape, or hand-pick at night.
Aphids: Blast them off with a strong spray of water or use insecticidal soap.
Tipburn: Brown edges on leaves from uneven watering or calcium deficiency. Keep soil evenly moist and add compost.

FAQs: Lettuce Planting in NorCal

What month is best to plant lettuce in Northern California?

For most inland areas, February-March (spring) and September-October (fall) are the prime months. On the coast, you can plant almost every month except the peak of winter.

Can you grow lettuce in Northern California year-round?

In coastal microclimates, yes, with the right variety and minor frost protection. Inland and in the mountains, you can have two long productive seasons (spring and fall) that nearly span the year.

How late can you plant lettuce in California?

For a fall crop that matures before hard frosts, aim to get seeds in the ground by mid-October for valleys, and late October or early November for coastal areas. Winter planting under cover can happen even later.

Does lettuce need full sun in our climate?

In spring and fall, yes, aim for 6 hours of sun. During our intense summer heat, lettuce benefits from partial afternoon shade to prevent bolting and bitterness.

By aligning your planting dates with NorCal’s unique seasons and choosing appropiate varieties, you can enjoy homegrown lettuce for much of the year. It’s all about timing and a little bit of local know-how. Keep notes on what works in your specific garden, and you’ll refine your schedule for perfect harvests every season.