California · zones 7a–10b
When to plant tomatoes in California.
Sow or transplant between Jan 21 to Mar 23 in a typical year, keyed to California's median last frost around Jan 14. Dates below are state medians; your ZIP code shifts them by days to weeks.
The 2026 windows
Tomatoes dates for a typical California season.
1 · Start indoors
Dec 10 to Feb 9
About 6 weeks before set-out. Warm spot, real light.
2 · Set out
Jan 21 to Mar 23
Keyed to the ~Jan 14 last frost. Sow 0.25" deep, 24" apart.
Harvest
~73 days later
~12 lb per plant over ~8 weeks.
California spans more than one climate: Zone 10 is the most common zone, but the state runs 7a to 10b. That's why the planner works from your ZIP code's frost dates, not your zone: mountain and coastal gardens in the same state can be three weeks apart.
California growing notes
Tomatoes split California's map into two problems.
Fog belt cool vs valley heat: opposite failures
Coastal California, from the Bay Area down through the fog-prone stretches near the water, keeps summer nights in the 50s, and tomato pollen turns sluggish below about 55 degrees, which shows up as flowers that yellow and drop without ever setting fruit. Inland, the Central Valley runs the opposite failure: fruit set stalls once daytime highs climb past 85 degrees and nighttime lows will not drop back under 70, and a plant can flower for weeks in July with almost nothing to show for it because the pollen itself has stopped functioning in that heat.
Match variety to the failure you are fighting. Early Girl, developed for cool, foggy growing conditions, sets fruit reliably in coastal gardens where other varieties stall. Celebrity and other heat-set types hold production through Central Valley summers better than beefsteak types bred for milder climates, because they keep flowering through short heat spikes instead of dropping the whole cluster. Either way, a plant that stops setting fruit for a week or two during a heat spike or a cool spell is not dead; it usually resumes once temperatures move back into the 55 to 85 degree range where pollen behaves normally.
Staking against coastal humidity, not just wind
Coastal fog keeps foliage damp well into the morning, and that lingering moisture is what early blight and other leaf fungi need to establish. Stake or cage every plant so the lower leaves stay off the ground, and strip the bottom foot of foliage once the plant is established; airflow through the lower canopy dries leaves an hour or two faster than a sprawling, unstaked plant.
Water at the base rather than overhead, especially in coastal gardens where the fog itself already keeps foliage wetter than inland gardens ever see. A soaker hose or drip line under the mulch keeps water off the leaves entirely and is the single change that cuts blight pressure the most in a foggy garden. Prune out any lower leaf that already shows the dark, target-ringed spots of early blight as soon as you spot it, since those spots are where the fungus sporulates and spreads upward through the plant.
Deep, infrequent watering for valley heat
Central Valley gardeners do better watering deeply and less often than the coast requires. Once plants are established, water to wet the soil 8 to 10 inches down, then let the top few inches dry before watering again; that pattern pushes roots down where soil temperature swings less, and plants handle a 100-degree afternoon far better on a deep root system than a shallow, frequently watered one.
Mulch 3 to 4 inches deep around Central Valley plants to slow evaporation from the fast-draining, often sandy soils common across the valley floor. Blossom end rot, the black leathery patch on the fruit bottom, shows up fastest in valley gardens that swing between bone dry and soaked; steady moisture through a thick mulch layer prevents more of it than any calcium spray applied after the fact.
In California: watch for
The pests that find tomatoes here.
With about 334 frost-free days, tomato, slicing spends longer in the ground here than in most of the country, which widens the window in which tomato hornworm can find it. Scout weekly from midseason and act on the first signs.
Big green caterpillars strip leaves and leave black droppings.
Organic fix: Handpick at dusk; spray Bt on the young ones.
Clusters on new growth, sticky leaves, curling tips.
Organic fix: Blast with water, then insecticidal soap or neem.
Dark spots with concentric rings, starting on the lowest, oldest leaves.
Organic fix: Remove affected leaves, mulch to stop soil splash, space for airflow.
Greasy, water-soaked blotches in cool, wet spells. No rings, and not bottom-up.
Organic fix: Pull infected plants fast, keep leaves dry, use neem as a preventive.
Septoria leaf spot
Many small tan spots with dark brown edges, low leaves first, no rings inside.
Organic fix: Strip the lowest leaves, mulch against soil splash, stake for airflow.
Your season math: California gives tomatoes about 334 frost-free days, and it needs roughly 73 days to a first harvest. It's a one-planting crop, so time that single sowing well.
Planting tomatoes in California: questions
When should I plant tomatoes in California?+
In a typical California year, sow tomatoes or set out transplants between Jan 21 to Mar 23, keyed to the state's median last frost around Jan 14. Your exact dates shift with your ZIP code and microclimate.
When do I start tomatoes seeds indoors in California?+
Start seeds inside about 6 weeks before set-out: roughly Dec 10 to Feb 9 for a typical California season.
What USDA zone is California?+
California spans zones 7a–10b, mostly zone 10. But frost dates, not zones, set planting time. The free planner uses your ZIP code's actual frost dates.
How many tomatoes plants do I need?+
Depends who you're feeding. The crop page has exact counts per household size, or the free planner does the math for your family in about 60 seconds.