Hawaii · zones 12a–12a
When to plant zucchini in Hawaii.
Sow between Jan 8 to Apr 23 in a typical year, keyed to Hawaii's median last frost around Jan 1. A second, fall sowing fits Sep 16 to Oct 5. Dates below are state medians; your ZIP code shifts them by days to weeks.
The 2026 windows
Zucchini dates for a typical Hawaii season.
Direct sow
Jan 8 to Apr 23
Keyed to the ~Jan 1 last frost. Sow 1" deep, 24" apart.
Fall round
Sep 16 to Oct 5
Counted back from the ~Dec 31 first frost.
Harvest
~50 days later
~8 lb per plant over ~5 weeks.
Hawaii spans more than one climate: Zone 12 is the most common zone, but the state runs 12a to 12a. 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.
Hawaii growing notes
Zucchini here turns over fast enough for eleven rounds a year, but melon fly alone can erase a round's numbers before either of the other two problems gets a chance.
Eleven rounds changes what a bad planting costs
At just 50 days from seed to first squash, zucchini turns over fast enough to fit as many as 11 staggered sowings into a year with no true close-out date. Give each planting real room, a full 24 inches between plants and about an inch of soil over the seed, since this crop's leaves spread wide enough to close a canopy fast, and a stand packed any tighter traps humidity right at the crown. Two or three plants running at a time, each one good for something in the range of 8 pounds before it is pulled and replaced, covers most households without ever piling up a glut.
That turnover changes the math on a struggling planting more than any yield number does. Once nothing forces a break in growing, a stand that is losing ground to a pest or a disease buildup is rarely worth nursing along; pulling it and reseeding a few weeks later usually gets squash back into the kitchen faster than fighting to save a plant that is already behind, a trade that would not make sense on a crop planted just once a year.
Losses of 30 to 100 percent make melon fly worth checking for on every visit
Melon fly is the reason a zucchini planting can fail even when everything else about it looks healthy. Eggs go in 2 to 4 mm deep in the fruit tissue, and the maggots that hatch feed from inside the fruit while it still looks fine from the outside. By the time the sting mark on the skin dimples inward and starts seeping, then dries into a small brown patch of hardened resin, real damage has already been done, and an unprotected planting can lose anywhere from 30 to 100 percent of its fruit this way.
Two habits do most of the work against it, and neither one is a spray. Slip a paper bag over each young fruit a few days after it sets so the female never gets a chance to reach bare skin. Anything that drops on its own, or already shows that dried resin patch, should go straight into a hole in the ground rather than onto a compost heap; burying is what keeps the next generation of flies from digging their way back out. Melon fly stays active right through the year here, so folding both habits into every one of the eleven rounds matters more than treating either as a single fix.
Elevation decides whether mildew or the beetles get there first
Powdery mildew and cucumber beetles split fairly evenly as the other two problems worth watching, and which one shows up first tends to follow the land. A zucchini plant's own leaves shade its crown solidly by the time it is fruiting hard, and a garden set higher up, where morning cloud and cooler air hang on longer before burning off, gives that shaded pocket even more time to stay damp. That is where powdery mildew's pale, dusty film tends to show up earliest, usually low on the plant, on the oldest leaves closest to the center.
Closer to the coast, where onshore breeze keeps air moving through the garden most of the day, leaves dry out faster and mildew is generally the smaller worry of the two. Cucumber beetles do better in that same warm, breezy air instead, and are easiest to catch early at the base of a young seedling, where a small plant has the least leaf area to spare. A planting site with some airflow around it, or simply thinning a stand that has grown too thick, does more for this crop than anything reached for after symptoms already show.
In Hawaii: watch for
The pests that find zucchini here.
With about 364 frost-free days, squash, summer spends longer in the ground here than in most of the country, which widens the window in which melon fly can find it. Scout weekly from midseason and act on the first signs.
Melon fly
Small punctures on young fruit that weep and darken to a resinous spot, then maggots inside and the fruit rotting or going misshapen.
Organic fix: Bag each fruit in paper a few days after it sets, and bury every fallen or infested fruit deep rather than composting it.
Yellow striped or spotted beetles chewing leaves and blossoms.
Organic fix: Row cover until the first female flowers open, then hand-pick.
White powder coating the leaves late in the season.
Organic fix: Space for airflow, water the soil rather than the leaves, use resistant varieties.
Your season math: Hawaii gives zucchini about 364 frost-free days, and it needs roughly 50 days to a first harvest. That fits about 11 re-sown rounds across the season, so you can keep it coming instead of picking once.
Planting zucchini in Hawaii: questions
When should I plant zucchini in Hawaii?+
In a typical Hawaii year, sow zucchini between Jan 8 to Apr 23, keyed to the state's median last frost around Jan 1. There's also a fall window: Sep 16 to Oct 5. Your exact dates shift with your ZIP code and microclimate.
What USDA zone is Hawaii?+
Hawaii spans zones 12a–12a, mostly zone 12. But frost dates, not zones, set planting time. The free planner uses your ZIP code's actual frost dates.
How many zucchini 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.