Hawaii · zones 12a–12a
When to plant sweet potatoes in Hawaii.
Sow or transplant between Feb 7 to Mar 24 in a typical year, keyed to Hawaii's median last frost around Jan 1. Dates below are state medians; your ZIP code shifts them by days to weeks.
The 2026 windows
Sweet Potatoes dates for a typical Hawaii season.
1 · Start indoors
Dec 27 to Feb 10
About 6 weeks before set-out. Warm spot, real light.
2 · Set out
Feb 7 to Mar 24
Keyed to the ~Jan 1 last frost. Sow 3" deep, 14" apart.
Harvest
~110 days later
~2.5 lb per plant over ~1 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
Sweet potato is 'uala here, a plant Polynesian voyagers carried across the Pacific long before it was a garden vegetable, and the one crop in this set that finds Hawaii's warmth a real advantage rather than an obstacle.
A crop that arrived by canoe, and never really left
Long before sweet potato was a line on a planting calendar, it was 'uala, one of the food plants Polynesian voyagers carried here, alongside taro and banana, when they first settled these islands. The plant did not originate in the Pacific; it traces to the Americas, reaching Hawaii on those same canoes. Once established, 'uala became a staple alongside taro, but the two asked different things of the land: taro wants a steady supply of fresh water, traditionally grown in flooded pondfields, while 'uala tolerated drier, rockier ground a pondfield could never use. That difference let farming communities feed themselves on land taro could not reach.
That same tolerance for dry, marginal ground is what makes 'uala the strongest performer on this calendar. Nearly every other crop here works around something lowland Hawaii cannot fully supply, like a bulb onion waiting on daylight that barely changes. Sweet potato asks for none of that; it vines out and builds roots in steady warmth because steady warmth is what it evolved for, and a gardener growing it here works with the climate for once.
One long planting, not the relay some crops here run
Sweet potato goes in as a transplant, but not a seedling grown from true seed; it is a slip, a rooted shoot cut from a mature root, set about 14 inches apart and 3 inches deep, with a harvest around 110 days out and a solid return, about 2.5 pounds per plant. Only the earlier window is marked open, and just a single round scheduled, closer to how this calendar treats a sprawling vine like watermelon than a fast row crop. The vines need room to run, and the bed stays committed to this one planting for most of its life.
How a slip goes into the ground affects how much comes back out. Setting it at a shallow angle, with two or three leaf nodes buried rather than just the base, gives each buried node a chance to root and swell into a tuber of its own. It also pays to go light on rich, high-nitrogen feeding once vines are established; a plant pushed hard on nitrogen spends that energy on leaves rather than the roots underneath.
The weevil that ruins a root without eating much of it
Sweetpotato weevil is the pest worth building the season around. It is slender and ant-like rather than round like most weevils, easy to mistake for a large ant. Adults chew small holes in leaves and vines, but the larvae do the real damage, tunneling inside the root, and the root's own defense against that tunneling produces a bitter, off-smelling compound that spreads through the flesh well beyond the tunnel; a root can be ruined by a weevil that damaged only a small part of it. The adult needs exposed root or a crack in dry soil to lay eggs, so keeping soil mounded high over the root zone, and watering evenly enough that the ground never cracks open, does more than anything sprayed on after the fact.
Wireworms and white grubs, the larvae of click beetles and scarab beetles, tunnel small round holes into roots from the outside, and turn up worse in a bed only recently converted from lawn. Aphids cluster on the soft new growth at the vine tips, and a hard spray from the hose knocks a light colony back before it spreads. Black rot turns up as dark, sunken lesions on the root itself rather than the leaves, and it can ride in on an infected slip before the plant is ever in the ground, so starting from slips that look clean and firm beats any treatment applied later; a root can already taste bitter from it even when the outside still looks fine.
In Hawaii: watch for
The pests that find sweet potatoes here.
With about 364 frost-free days, sweet potato spends longer in the ground here than in most of the country, which widens the window in which sweetpotato weevil can find it. Scout weekly from midseason and act on the first signs.
Sweetpotato weevil
Narrow tunnels through roots, and a bitter taste that survives cooking.
Organic fix: Plant certified slips, rotate the bed, and destroy any vine with a wilting runner.
Chinese rose beetle
Leaves chewed to lace between the veins, with no insect in sight by day.
Organic fix: Go out after dark with a jar of soapy water and pick them off, or hang a dim light over a soapy tray to trap them.
Wireworms & white grubs
Shallow holes and grooves chewed into the roots, found only at digging time.
Organic fix: Avoid planting into ground that was in sod last year; rotate away from grassy beds.
Clusters on the tender growing tips of new vines.
Organic fix: Hose them off in the morning, or use insecticidal soap.
Black rot
Dry, firm dark patches on the roots, usually found at harvest or in storage, with a sweet fruity smell.
Organic fix: Start from clean slips cut well above the soil line, never save roots from a bad crop, and rotate 3 years.
Your season math: Hawaii gives sweet potatoes about 364 frost-free days, and it needs roughly 110 days to a first harvest. It's a one-planting crop, so time that single sowing well.
Planting sweet potatoes in Hawaii: questions
When should I plant sweet potatoes in Hawaii?+
In a typical Hawaii year, sow sweet potatoes or set out transplants between Feb 7 to Mar 24, keyed to the state's median last frost around Jan 1. Your exact dates shift with your ZIP code and microclimate.
When do I start sweet potatoes seeds indoors in Hawaii?+
Start seeds inside about 6 weeks before set-out: roughly Dec 27 to Feb 10 for a typical Hawaii season.
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 sweet potatoes 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.