When to plant zucchini / summer squash in Hawaii
Hawaii is essentially frost-free (USDA zones 9b, 10a, 10b, 11a, 11b, 12a, 12b, 13a), so zucchini / summer squash timing there is set by heat and daylength rather than frost. As a warm-season crop, the main risk is mid-summer heat — spring and late-summer plantings usually do best.
Hawaii covers a wide range of climates, so your exact frost dates may differ from the state average by two weeks or more. For dates tuned to your town, use the calendar generator.
When to plant zucchini / summer squash in Hawaii: the short answer
For a spring planting, sow Feb 3 – Feb 22, with seeds started indoors Jan 4 – Jan 18. Wait until the soil is at least 60°F and frost is over.
Your area is essentially frost-free, so planting dates are set by heat and daylength rather than frost. Treat the ranges below as broad season guides.
Warm-season crop: in a frost-free area the main risk is mid-summer heat; spring and late-summer plantings usually do best.
Windows are ~1–2 week bands around each date. Frost dates are a statewide average from NOAA/NCEI normals; your town may differ by two weeks or more. Calendar year 2026.
How to grow zucchini / summer squash in Hawaii, step by step
- Start seeds indoors (Jan 4 – Jan 18). Sow seeds 1 inch deep in seed-starting mix under bright light. They take 5-10 days to sprout, fastest in soil around 85°F. Harden seedlings off for a week before they go outside.
- Prepare the bed. It needs at least six to eight hours of direct sun a day and loose soil at least 14 inches deep, with a pH between 5.5 and 7.5. Dig in compost before planting.
- Sow outdoors (Feb 3 – Feb 22). Space plants about 30 inches apart in rows 42 inches apart, sowing seed 1 inch deep. It is killed by frost, so nothing goes outside until the danger has passed.
- Water and feed. Give it steady, even moisture, about an inch of water a week from rain or the hose.
- Watch for pests and problems. Pests: squash vine borer, squash bug, striped cucumber beetle, aphids. Diseases and disorders: powdery mildew, bacterial wilt, blossom-end rot (calcium disorder).
- Harvest (from about Mar 25 – Apr 9). Zucchini / Summer Squash takes 45-60 days to reach harvest. One or two plants feed a household. A second sowing in early-mid summer dodges the first vine borer generation.
Figures come from our crop data; dates use Hawaii’s average frost dates. More in the full zucchini / summer squash growing guide.