Planting months by climate zone
The chart comes from the same data as the planting calendar. Tap a zone for its full calendar and the towns it covers.
| Zone | J | F | M | A | M | J | J | A | S | O | N | D | Sow or plant |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Tropical | yes | yes | yes | yes | yes | yes | yes | yes | yes | yes | yes | yes | All year |
| Subtropical | yes | yes | yes | yes | yes | yes | yes | yes | yes | Aug–Apr | |||
| Arid and semi-arid | yes | yes | yes | yes | Sep–Dec | ||||||||
| Temperate | yes | yes | Oct–Nov | ||||||||||
| Cool | No agreed months | ||||||||||||
| NZ warm north | yes | yes | yes | Oct–Dec | |||||||||
| NZ temperate | yes | yes | yes | Oct–Dec | |||||||||
| NZ cool south | Not suited |
plantnot recommendedthis month
The Diggers Club gives soil above 20 °C as the threshold, which is why temperate gardens only have October and November. Planted then, the crop has time to mature before autumn cools the soil again. No cool-zone guide gives planting months, so that row is left open. In New Zealand, Tui gives no planting months for Canterbury, Otago or Southland. Kūmara is a warm-zone crop there, and commercial growers such as Kaipara Kūmara farm the alluvial plains of the northern Kaipara.
Slips: buy them or grow your own
A slip is a shoot, 10–15 cm or longer, taken from a sprouting sweet potato. In New Zealand, kūmara shoots (tupu) are in garden centres around October. To grow your own:
- In water. Tui cuts a kūmara and stands it in water. Shoots appear in 1–2 weeks. Once they are 10–15 cm long, snap them off and stand them in water until they root.
- In a tray. Virginia Cooperative Extension's master gardeners halve a sweet potato lengthwise, lay it cut side down in a tray of moist mix, and keep it warm and under lights. The shoots are ready to slip off, with leaves and a few roots, after about 6 weeks.
- Timing. Count back from your planting month: start a tuber about 6 weeks before the soil will be warm enough. Commercial kūmara growers in the Kaipara bed their seed roots from July to September for planting from October to December.
Planting
- Warm soil. Wait for about 20 °C. Slips planted into cold soil stall, and frost kills them outright.
- Lay them sideways. Tui plants each slip in a J shape so it grows along the ground, about 30 cm apart in a staggered pattern. The calendar gives 30–50 cm between plants and 90–100 cm between rows.
- Room to run. The vines spread a long way. Virginia's master gardeners allow for vines reaching at least 1.2 m from each plant in every direction, so sweet potatoes suit the edge of a bed where they can sprawl. The plant spacing calculator turns the spacing into a plant count.
Harvest, curing and storage
Tui puts the crop at about 120–150 days from planting, and the calendar at 16–25 weeks. Harvest once the leaves start to yellow, and always before the first frost. The skins are thin and easily damaged, so lift the roots carefully with a fork and handle them gently.
Curing heals the skin and sweetens the roots. There are two ways to do it at home:
| Method | How | Source |
|---|---|---|
| Commercial standard | 29 °C and 85–90 % humidity for 3–5 days, then store at 13 °C | NC State Extension |
| Warm room at home | 24–27 °C for about 10 days, then store at 16–18 °C | Virginia master gardeners |
| New Zealand garden method | A couple of days in the sun on the bed, covered at night, then a cool, dry place | Tui |
The one rule every source agrees on is to keep them out of the fridge. NC State Extension notes that sweet potatoes suffer chilling injury below 10 °C. Commercial kūmara are stored in temperature- and humidity-controlled sheds through winter, spring and early summer. Kaipara Kūmara says they cure and sweeten naturally as they are stored.
Questions
When should I plant sweet potato in Sydney?
October and November, the temperate-zone window, once the soil is above about 20 °C. Start your own slips from a tuber in August or September so they are ready in time.
When do you plant kūmara in New Zealand?
From October, once the risk of frost has passed, through to December. Tui notes that shoots are in garden centres around October. Kūmara needs a long, warm summer, so it grows best in the north and centre of the North Island.
How long do sweet potatoes take to grow?
About 120–150 days from planting the slips, according to Tui, or four months for commercial kūmara in the Kaipara. Harvest when the leaves yellow and before the first frost.
Can I store sweet potatoes in the fridge?
No. Sweet potatoes are injured by temperatures below 10 °C, according to NC State Extension. Cure them warm after harvest, then keep them somewhere cool and dry, ideally around 13–18 °C.
Sources
- Tui, Kūmara growing guide – planting after frost, shoots in water, J-shape planting and spacing, 120–150 days, harvest and curing in the sun.
- NC State Extension, Postharvest handling of sweetpotatoes – curing at 29 °C and 85–90 % humidity, storage at 13 °C, chilling injury below 10 °C, delicate skin.
- Piedmont Master Gardeners (Virginia Cooperative Extension), How to grow your own sweet potato slips – slips from a halved tuber in about 6 weeks, spacing, vine spread, home curing.
- Kaipara Kūmara, Growing kūmara – northern Kaipara growing area, bedding July–September, transplanting October–December, four-month cycle, storage.
- Planting months by zone: the GardenMaths planting calendar, from the Diggers Club (soil above 20 °C), the NT Government, ABC Gardening Australia, Tui and others listed on each zone page.
Last reviewed 24 September 2026 · Report an error