Tomatoes are the crop that makes a Zone 10 vegetable garden, and Zone 10 gives them one of the longest seasons in the country: with frost rare and average winter lows of 30 to 40°F, there is time for big indeterminate varieties to grow tall, for two plantings a year, and for slow varieties that would run out of season further north.
The Zone 10 challenge is not cold, it is heat. Tomatoes set fruit poorly when nights stay very hot, so the best crops come from the cooler months — a spring planting that fruits before the worst summer heat, and an autumn planting that fruits through winter.
Zone 10 at a glance
USDA Zone 10 covers the warmest parts of the United States, including southern Florida, southern coastal California, Hawaii and Puerto Rico. Winters are very mild, with average winter lows of 30 to 40°F, frost is rare, and the growing season runs nearly all year.
The average last spring frost is Jan 15–30 (frost rare) and the average first autumn frost is Dec 15–31 (frost rare) — USDA/NOAA averages, not exact dates, so check your local extension service before planting.
| Detail | Zone 10 guidance |
|---|---|
| Average winter low | 30 to 40°F |
| Average last spring frost | Jan 15–30 (frost rare) |
| Average first autumn frost | Dec 15–31 (frost rare) |
| Days to germination | 7–14 days |
| Days to maturity | 60–85 days |
| Sowing | start indoors |
| Sun | full sun |
| Soil pH | 6.0–6.8 |
| Spacing | 24–36 inches |
| Water needs | high |
| Cold tolerance | tender |
When to plant tomatoes in Zone 10
Plant tomatoes in Zone 10 in two seasons: a spring planting from February through April, and an autumn planting from August through September. Seeds germinate in 7–14 days and fruit matures in 60–85 days, so a February planting is cropping by April or May, and an August planting fruits from October onwards. The average last spring frost in Zone 10 is Jan 15–30, with frost rare, and the average first autumn frost is Dec 15–31, with frost rare — those are USDA zone averages, not exact dates for any one garden, so always check your local extension service for your own frost dates. In practice, frost is rare enough that the calendar matters more than the frost dates: the real limits are summer heat, which stops fruit setting, and the short days of midwinter, which slow growth.
Work back from the frost dates: the planting calendar hub and the February in Zone 10 month guide show what else is happening at planting time.
Starting tomatoes in Zone 10
Start tomatoes indoors from seed, six to eight weeks before you plan to plant out — sow in February for a spring planting, and in July for an autumn planting. Sow seed in warm conditions; germination takes 7–14 days. Grow seedlings in the strongest light you can give them, potting them on once or twice and burying the stem deeper each time, since tomatoes root all along the buried stem. Harden them off for a week, then transplant out once nights are reliably mild, spacing plants 24–36 inches apart. Put supports in at planting time — stakes, cages or string — before the roots spread, because a tomato that is staked late is a tomato that is damaged.
See also when to plant tomatoes in Zone 8 for the same crop in a cooler zone.
Soil, spacing, sun and water
Tomatoes need full sun and rich, well-drained soil with a pH of 6.0–6.8. Dig in well-rotted compost before planting — tomatoes are heavy feeders, and a hungry plant produces few fruit. Space plants 24–36 inches apart so air can move between them; crowded plants stay damp and invite disease. Water needs are high: water deeply and regularly, keeping the soil consistently moist, because uneven watering causes blossom-end rot and split fruit. Mulch thickly to hold moisture and keep roots cool, and water at the base in the morning so leaves dry before night. The plant spacing calculator can help you plan the bed before you plant.
Companion planting
Good companions for tomatoes include basil, marigolds, carrots, onions and parsley. Carrots and onions fill the gaps between young plants and are harvested before the tomatoes need the space. Bell peppers are another heat-loving Zone 10 crop that shares the same spring and autumn planting windows, and our guide to when to plant bell peppers in Zone 10 shows how the two can be timed together. The companion planting finder can suggest combinations for your whole bed.
Pests and problems
The common pests and problems to watch for with tomatoes are aphids, tomato hornworm, whiteflies, cutworms and blight. Aphids cluster on soft new growth; wash them off with a strong jet of water and encourage ladybirds. Tomato hornworms are big green caterpillars that strip leaves fast; hand-pick them, checking the undersides of leaves. Whiteflies flutter up in clouds when disturbed and feed on the undersides of leaves; yellow sticky traps and good air flow help. Cutworms chew through young stems at soil level overnight; a cardboard collar around each seedling stops them. Blight shows as dark spots on leaves and fruit in wet weather; water at the base, space plants well and remove affected leaves promptly.
Harvest and storage
Tomatoes take 60–85 days to maturity from transplanting, so Zone 10 spring plants set out in February start cropping in April or May, and autumn plants set out in August fruit from October onwards. Pick fruit when it is fully coloured but still firm, and pick in the morning when plants are cool. If a rare frost is forecast, pick green fruit before it arrives — green tomatoes will ripen indoors on a windowsill, or can be used for chutney.
Frequently asked questions
When should I plant tomatoes in Zone 10?
Plant in two seasons: spring (February–April) and autumn (August–September). Seeds germinate in 7–14 days and fruit matures in 60–85 days. Frost is rare in Zone 10, so the real limits are summer heat, which stops fruit setting, and short winter days.
Why are my tomatoes not setting fruit in summer?
Heat — tomatoes set fruit poorly when nights stay very hot. In Zone 10, the best crops come from spring and autumn plantings that fruit in the cooler months. Choose heat-tolerant varieties for summer, and keep plants well watered.
How far apart should I space tomatoes in Zone 10?
Space plants 24–36 inches apart, in full sun and soil with a pH of 6.0–6.8. Crowding slows growth and invites disease, which matters more in a long, humid season.
What pests affect tomatoes in Zone 10?
The most common are aphids, tomato hornworm, whiteflies, cutworms and blight. Inspect leaves regularly and act early; healthy, well-spaced plants resist pests better than stressed ones.