Plant tomatoes in California between late February and early April for spring harvest, or in mid-summer for fall crops — the exact date depends on your region and frost risk.

California's long growing season means you can plant tomatoes twice a year, but the timing shifts dramatically between the coast, inland valleys, and mountains. The key is soil temperature: tomato seeds and seedlings need soil at least 60°F, and they grow fastest when it stays between 70°F and 85°F. Planting too early into cold soil causes seeds to rot and seedlings to sit dormant. Planting too late into extreme heat stresses young plants and reduces fruit set.

Your frost date — the last spring freeze your area typically sees — is the hard important date. Tomatoes die at 32°F. If you plant seedlings before that date passes, a late frost will kill them. The USDA Hardiness Zone map and your local Cooperative Extension office both publish frost dates by county, and these dates vary by as much as eight weeks across the state.

Key Takeaways

  • Coastal California (San Francisco, San Diego, Los Angeles) has frost risk through April or May, so plant seedlings in late April or May rather than March.
  • Inland valleys (Sacramento, Fresno, Bakersfield) warm faster and have frost dates in mid-March to early April, allowing planting in late March or early April.
  • Mountain and foothill areas (Lake Tahoe, mountain counties) have frost dates in May or June, so wait until late May or June to plant outdoors.
  • A second planting in mid-July to early August produces a fall crop that matures before the first frost in October or November, depending on your location.
  • Start seeds indoors six to eight weeks before your target planting date, or buy seedlings from a nursery four to six weeks before you plan to set them in the ground.

Coastal Regions: San Francisco, Los Angeles, and San Diego

Coastal areas stay cool longer because of ocean influence, and frost can arrive as late as May. San Francisco's last frost date is typically around May 15. Los Angeles and San Diego are warmer but still see frost risk through late April. Soil in coastal gardens often stays below 60°F until late April, even when air temperatures climb.

Plant seedlings outdoors in late April or May in these regions. If you start seeds indoors, begin them in early March so seedlings are ready to transplant by late April. Buying nursery seedlings in late April and planting them when ready is often simpler than timing seed-starting at home. Coastal tomatoes also benefit from afternoon shade in summer, since the heat can be intense once it arrives.

Inland Valleys: Sacramento, Fresno, Bakersfield, and Modesto

Inland valleys warm much faster than the coast. Sacramento's last frost date is around April 15, Fresno's is around April 10, and Bakersfield's is around March 30. Soil in these areas reaches 60°F by late March and 70°F by mid-April. You can plant seedlings outdoors in late March or early April without frost risk.

Start seeds indoors in early February if you want to transplant seedlings in late March. Alternatively, direct-seed tomatoes into the ground in mid-April when soil is warm enough. These regions heat up quickly in May and June, so plant early-maturing varieties if you want a harvest before July heat stresses the plants. A fall crop planted in mid-July will mature in September and October before the first frost, which typically arrives in late October or early November.

Mountain and Foothill Areas: Lake Tahoe, Sierra Nevada, and Higher Elevations

Mountain regions have the shortest growing season and the latest frost dates. Areas above 3,000 feet elevation often see frost risk through May or even early June. Lake Tahoe's last frost date is around June 15. Soil in these areas warms slowly, and nighttime temperatures stay cool even in summer.

Wait until late May or June to plant seedlings outdoors. Start seeds indoors in March or April, or buy nursery seedlings in May and plant them when ready. Choose early-maturing varieties (60 to 70 days to harvest) so fruit has time to ripen before the first fall frost, which can arrive in September. A second planting is usually not practical in mountain areas because the fall frost comes too early for a second crop to mature.

Spring Planting: Seeds Versus Seedlings

You can start tomatoes from seed indoors or buy seedlings from a nursery. Seeds take longer but cost less and give you more variety choices. Seedlings are faster and reduce the risk of damping-off disease, which kills young seedlings in wet soil.

If you start seeds indoors, sow them six to eight weeks before your target transplant date. Use a seed-starting mix (not garden soil), keep it moist but not waterlogged, and provide 14 to 16 hours of light daily under grow lights or in a bright window. Seedlings are ready to transplant when they have two sets of true leaves and are 3 to 4 inches tall. Harden them off by placing them outdoors in shade for a few hours daily, gradually increasing sun exposure over a week, before planting them in the garden.

Nursery seedlings are usually ready to plant when ready. Choose stocky, dark-green plants with no flowers yet — flowering seedlings are stressed and often produce less fruit. Plant them deeper than they were in the pot; tomatoes will root along the buried stem and develop a stronger root system.

Summer Planting for Fall Harvest

A second tomato crop planted in mid-July to early August produces fruit in fall when temperatures cool and disease pressure drops. This timing works in inland valleys and coastal areas but is risky in mountains because the first frost arrives too soon.

Plant seedlings (not seeds) in mid-July to early August so they mature before the first frost. In Sacramento and Fresno, the first frost typically arrives in late October or early November, giving you 12 to 14 weeks for fruit to mature. In coastal areas, frost may arrive in November, extending the window slightly. Choose early-maturing varieties and remove flowers that appear after mid-September so the plant focuses energy on ripening existing fruit rather than setting new fruit that won't mature in time.

Soil Temperature and Frost Date Resources

Soil temperature matters more than air temperature. A soil thermometer costs $10 to $20 and takes the guesswork out of planting. Insert it 4 inches deep in the morning; wait until it reads 60°F consistently before planting seeds, and 65°F to 70°F for best seedling growth.

Your county's Cooperative Extension office publishes frost dates specific to your area and elevation. Search "[your county] California Cooperative Extension" online to find their website. The USDA Hardiness Zone map (planthardiness.ars.usda.gov) also shows frost dates by zip code. Local nurseries often have frost date information posted or can tell you the typical dates for your area.

Frequently Asked Questions

Can I plant tomatoes in winter in California?

Not outdoors in most of California. Winter soil is too cold for seeds to germinate or seedlings to grow. Coastal areas with very mild winters (San Diego, parts of Los Angeles) can plant in late January or February for a spring harvest, but frost risk remains high through April. Inland and mountain areas must wait until spring.

What happens if I plant tomatoes too early?

Seeds rot in cold soil. Seedlings sit dormant, turn purple, and grow slowly until soil warms. A late frost kills seedlings outright. Waiting two to three weeks for soil to warm produces faster growth and healthier plants than planting too early.

Is it too late to plant tomatoes in June?

In most of California, yes. Tomatoes planted in June face extreme heat in July and August, which reduces fruit set and stresses plants. In coastal areas and mountains, June planting can work if you choose heat-tolerant varieties and provide afternoon shade. For a fall crop, plant in mid-July instead.

Do I need to cover seedlings if frost is forecast after I plant?

Yes. Row covers, blankets, or even cardboard boxes trap heat and protect seedlings from frost. Cover plants in the late afternoon before frost arrives and remove covers the next morning once temperatures rise above 50°F. This buys you a week or two of frost protection if an unexpected late freeze occurs.

What's the difference between determinate and indeterminate tomatoes for California planting?

Determinate varieties mature all their fruit at once in 60 to 75 days, making them good for fall crops and canning. Indeterminate varieties produce fruit continuously until frost, making them better for spring planting and fresh eating. Both work in California; choose based on whether you want one big harvest or fruit all season.