Zucchini is the most generous crop in a Zone 10 garden — famously too generous, since a single plant can produce more courgettes than a household can eat. It loves heat, it loves the long season, and in Zone 10 you can grow it in two seasons, spring and autumn, with a break in the hottest weeks when mildew takes hold.
The Zone 10 trick is to plant fewer than you think you need. One or two plants per household is usually plenty, and the rest of the bed can grow something else.
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 | 7–10 days |
| Days to maturity | 45–55 days |
| Sowing | both |
| Sun | full sun |
| Soil pH | 6.0–7.5 |
| Spacing | 36–48 inches |
| Water needs | moderate |
| Cold tolerance | tender |
When to plant zucchini in Zone 10
Plant zucchini in Zone 10 in two seasons: a spring planting from February through May, and an autumn planting from August through October. Seeds germinate in 7–10 days and fruit matures in 45–55 days, so a February sowing is picking by April, and an August sowing 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. Zucchini is tender and needs warm soil, so do not sow until nights are reliably mild. In the hottest weeks of midsummer, powdery mildew spreads fast and fruit setting can slow — the spring and autumn plantings usually out-yield a midsummer one.
Work back from the frost dates: the planting calendar hub and the April in Zone 10 month guide show what else is happening at planting time.
Starting zucchini in Zone 10
Direct-sow zucchini where it is to grow — it dislikes root disturbance — or start it indoors in large pots two to three weeks before planting out. Sow two seeds per station about an inch deep, in a small mound of compost-rich soil, and thin to the strongest seedling once they have a couple of true leaves. Space stations 36–48 inches apart, because a zucchini plant is a big, sprawling thing that will fill its space and more. If you start seed indoors, transplant very carefully, keeping the root ball intact, and harden plants off for a week first. Water seedlings in well and mulch immediately.
See also when to plant zucchini in Zone 8 for the same crop in a cooler zone.
Soil, spacing, sun and water
Zucchini needs full sun and rich, well-drained soil with a pH of 6.0–7.5. Dig in generous amounts of well-rotted compost before planting — zucchini are heavy feeders, and a hungry plant produces few fruit. Space plants 36–48 inches apart so air can move through the leaves; crowded plants stay damp and invite mildew. Water needs are moderate: water deeply at the base, keeping leaves as dry as possible, and water in the morning so foliage dries before night. In Zone 10 summer heat, a deep watering two or three times a week beats a daily sprinkle. Mulch thickly to hold moisture and keep roots cool. The plant spacing calculator can help you plan the bed before you plant.
Companion planting
Good companions for zucchini include marigolds, basil, onions and lettuce. Marigolds at the bed edge help deter pests, onions can be tucked between young plants before the vines take over, and lettuce fills the gaps early in the season. Cucumbers are another warm-season Zone 10 cucurbit with the same timing, and our guide to when to plant cucumbers in Zone 10 shows how the two can share the summer bed. Avoid planting zucchini near potatoes, which are said to inhibit each other, and keep it away from plants it will swamp — a zucchini will shade out a small neighbour in a few weeks. The companion planting finder can suggest combinations for your whole bed.
Pests and problems
The common pests and problems to watch for with zucchini are cucumber beetles, squash bugs, aphids and powdery mildew. Cucumber beetles chew seedlings and spread disease — cover young plants with insect mesh until they flower, then remove it so pollinators can reach the blooms. Squash bugs hide under leaves and at the base of stems; check leaf undersides regularly and hand-pick them. Aphids cluster on soft new growth; wash them off with a strong jet of water. Powdery mildew is the most common Zone 10 summer problem: give plants space, water at the base, and remove badly affected leaves.
Harvest and storage
Zucchini takes 45–55 days to maturity from sowing, so Zone 10 spring plants sown in February are picking by April, and autumn plants sown in August fruit from October onwards. Pick fruit when it is young, tender and about 6–8 inches long — cut the stem with scissors or a knife rather than pulling, which damages the plant. Pick in the morning, when the fruit is cool, and pick little and often, every day or two in peak season: regular picking keeps the plant producing, while a single overgrown fruit left on the vine will slow the whole plant down. Store zucchini in the fridge and use within a week; they do not freeze well raw, but they freeze well if blanched or cooked.
Frequently asked questions
When should I plant zucchini in Zone 10?
Plant in two seasons: spring (February–May) and autumn (August–October). Seeds germinate in 7–10 days and fruit matures in 45–55 days. Wait until nights are reliably mild — zucchini needs warm soil.
How many zucchini plants do I need?
One or two per household is usually plenty — a single plant can produce more courgettes than a family can eat. Plant two only if you love zucchini, and pick the fruit small and often.
Why is my zucchini rotting at the blossom end?
Usually poor pollination — the female flower was not pollinated, so the tiny fruit rots. Hand-pollinate by transferring pollen from a male flower to a female flower with a small brush, and make sure pollinators can reach the blooms.