Plant tomatoes in California between late February and mid-March in the south, and mid-April to early May in the north—but the exact date depends on your last frost date and which variety you're growing.

California's long growing season and mild winters mean you can plant tomatoes earlier than most of the country, but frost still kills seedlings and young plants. The state's frost dates vary dramatically: coastal and mountain areas stay cold longer, while inland valleys warm up fast. Knowing your specific location's last frost date is the single most useful piece of information you can have before you buy a single seed.

Tomatoes need soil that has warmed to at least 60°F, ideally 65°F or warmer. A soil thermometer costs about $10 and removes the guesswork. If you plant into cold soil, seeds rot and transplants sit dormant instead of growing. Waiting two or three weeks for the soil to warm up beats replanting in May.

Key Takeaways

  • Southern California (San Diego, Los Angeles, inland valleys) can plant tomatoes from late February through March; frost risk drops sharply after mid-March.
  • Northern California (Bay Area, Sacramento Valley, mountain regions) should wait until mid-April to early May, when soil has warmed and frost danger has passed.
  • Check your local last frost date through the National Weather Service or your county extension office—this date is more reliable than a calendar month.
  • Soil temperature matters more than air temperature; tomatoes need soil at least 60°F to germinate and 65°F to grow steadily.
  • Determinate varieties (bush types) mature faster and suit short-season areas; indeterminate varieties (vining types) need a longer frost-free window.

Southern California Planting Windows

If you live in San Diego County, Los Angeles County, inland Riverside or San Bernardino counties, or the Central Valley south of Fresno, your last frost date typically falls between mid-February and early March. This means you can plant tomato transplants (seedlings started indoors or bought from a nursery) in late February and expect them to survive. Direct seeding (planting seeds straight into the ground) is riskier because seeds need warmer soil; most gardeners in these areas start seeds indoors in January or buy transplants.

The advantage of planting early in southern California is that your tomatoes will produce fruit through the summer and into fall. A tomato planted in late February can start flowering by May and give you ripe fruit by July. If you wait until April, you'll still harvest, but the season compresses—your plants may stop producing when heat peaks in August or when fall rains arrive in September.

Frost can still occur in March in southern California, especially in inland valleys and at higher elevations. Check your county's specific last frost date before planting. San Diego's is around March 15; inland areas like Victorville or Big Bear are closer to April 15. A late frost in March can kill young plants, so keep frost cloth or row covers handy if you plant early.

Northern California and Mountain Region Timing

Northern California—including the Bay Area, Sacramento Valley, Redding area, and mountain counties—has a later planting window. Most of these regions have last frost dates between April 15 and May 15. Coastal areas like Humboldt County stay cool even longer, sometimes into late May. If you plant tomatoes before your last frost date, a spring freeze will kill them.

The trade-off is that northern California's cooler nights and longer fall season can actually extend your harvest. A tomato planted in mid-May can still produce fruit into October or even November if you're in a sheltered valley. Indeterminate varieties (the tall, vining types that produce all season) do especially well here because they have time to mature before the first fall frost.

Soil warming is slower in northern California. Even if the air temperature reaches 70°F in April, the soil may still be 50°F. Wait until soil reaches at least 60°F before planting seeds or transplants. This usually happens in mid-to-late April in the valley and mid-to-late May in mountain areas and coastal regions.

Finding Your Exact Last Frost Date

Your last frost date is the average date of the final frost in spring for your specific location. It is not the same as your county's date—a town 20 miles inland can have a frost date two weeks later than a coastal town in the same county. The National Weather Service maintains frost date data by zip code. Search "last frost date" plus your zip code, or visit the National Weather Service website for your region.

Your county's Cooperative Extension office also has this information and can tell you about local microclimates. If you live on a hillside, in a valley, or near water, your frost date may differ from your town's average. A phone call to the extension office takes five minutes and can save you from planting too early.

Once you know your last frost date, add 7 to 10 days as a safety margin. If your last frost date is April 15, plant tomatoes around April 22 to 25. This buffer accounts for the fact that frost dates are averages, not guarantees.

Soil Temperature and Germination

Tomato seeds germinate best in soil between 70°F and 80°F, but they will germinate slowly in soil as cool as 60°F. Below 60°F, seeds often rot before they sprout. If you're direct seeding (planting seeds outdoors), wait until soil is at least 65°F. If you're planting transplants (seedlings), soil at 60°F is acceptable because the plant is already past the germination stage.

A soil thermometer is the most reliable way to check. Push it 4 inches into the soil in the morning, wait 5 minutes, and read the temperature. Do this for a few days in a row to get an average. If soil is still cold, wait another week and check again. Planting into cold soil is one of the most common reasons tomato plants sit stunted for weeks before finally growing.

In southern California, soil usually reaches 65°F by late February or early March. In northern California, this happens in mid-to-late April. Coastal areas and higher elevations take longer. If you're impatient, you can warm the soil by laying black plastic over the bed for a week or two before planting—the sun will heat the soil underneath.

Determinate vs. Indeterminate Varieties and Timing

Determinate tomatoes (bush types like Roma, San Marzano, and most paste varieties) grow to a fixed size, flower all at once, and produce most of their fruit in a short window—usually 4 to 6 weeks. They mature faster than indeterminate varieties and are better for short-season areas or if you want to harvest and preserve all at once. In northern California, determinate varieties are often the safer choice because they finish before fall frost arrives.

Indeterminate tomatoes (vining types like Brandywine, Cherokee Purple, and most heirloom slicers) grow continuously, flower and set fruit all season, and keep producing until frost kills them. They need a longer frost-free window—ideally at least 150 to 180 days. In southern California, indeterminate varieties thrive because the growing season is long. In northern California, they work too, but you need to plant early enough that they have time to mature before October or November frost.

If you're in a short-season area (northern mountains, coastal regions), choose determinate or early-maturing indeterminate varieties. If you're in southern California or a warm inland valley, you can grow any variety you want.

Spring vs. Fall Planting in California

California's mild winters mean you can also plant tomatoes in late summer for a fall and early-winter harvest. This second planting window opens around July 15 to August 15, depending on your region. Fall-planted tomatoes grow through the cooler months and produce fruit from October through December or even January in southern California.

Fall planting works best in southern California and warm inland valleys. In northern California, fall-planted tomatoes may not have enough time to mature before winter frost arrives. If you want to try fall planting, choose early-maturing varieties and plant by mid-August at the latest.

The advantage of fall planting is that you avoid the intense summer heat, which can cause blossom-end rot and reduce fruit set. Tomatoes actually prefer temperatures between 65°F and 75°F; when it hits 90°F or above, pollen becomes sterile and flowers drop without setting fruit. A fall crop often produces better-quality fruit than a summer crop in hot inland areas.

Frequently Asked Questions

Can I plant tomatoes in January in California?

Only in the warmest parts of southern California (coastal San Diego, parts of Los Angeles County) where frost is rare after early January. Inland and northern areas will see frost kill young plants. Check your specific last frost date before planting in winter.

What if I plant tomatoes too early and frost kills them?

If frost damages seedlings, they often recover if the damage is light (wilted leaves, not blackened stems). Cut off the damaged growth and let the plant regrow. If the stem is blackened or mushy, the plant is dead and should be removed and replanted.

Is it better to start seeds indoors or buy transplants?

Both work. Starting seeds indoors (6 to 8 weeks before your planting date) gives you more variety choices and costs less. Buying transplants is faster and removes the guesswork about when to start seeds. In California, most home gardeners buy transplants because the growing season is long enough that you don't lose much by planting later.

How do I know if my soil is warm enough?

Use a soil thermometer. Push it 4 inches deep in the morning, wait 5 minutes, and read the temperature. Tomatoes need soil at least 60°F for transplants and 65°F for seeds. If soil is cold, wait a week and check again.

Can I plant tomatoes in a container on a different schedule?

Container soil warms faster than ground soil because it's exposed to sun on all sides. You can plant tomatoes in containers about two weeks earlier than in the ground. Use a large pot (at least 5 gallons) and fill it with potting mix, not garden soil.