How to grow Popcorn in New Zealand
Popcorn is a different type of corn from sweet corn, with hard-shelled kernels that burst when heated. It is grown the same way, in a sunny block of warm soil, but the cobs are left on the plant until they are completely dry. It needs a long, warm season, so sow it as soon as the soil warms in spring.
📖 Our full guide: How to Grow Popcorn in New Zealand
At a glance
When to sow by region
| Region | When to sow | Regional note |
|---|---|---|
| Northland | October and November | |
| Auckland | October and November | |
| Waikato & Bay of Plenty | October and November | |
| Central North Island | November | Sow in November so the cobs dry before the April frosts. |
| Wellington & Lower North Island | November and December | |
| Nelson & Marlborough | November and December | |
| Canterbury | November and December | |
| Otago & Southland | December | |
| Central Otago | December |
Not to be confused with: Sweet corn, which is picked young and juicy. Keep the two well apart, as they cross-pollinate and the sweet corn kernels turn starchy.
Where to plant
Choose a sunny, sheltered spot with rich, well-drained soil. Corn is wind pollinated, so plant it in a block of several short rows rather than one long row, which gives well-filled cobs. Popcorn and sweet corn cross-pollinate, so grow them well apart or sow them so they flower at different times.
- Northland, Auckland, Waikato and the Bay of Plenty: sow from October once the soil is warm.
- Central North Island: sow in November so the crop matures before the April frosts.
- Wellington, Nelson and Canterbury: sow in November and December.
- Otago, Southland and Central Otago: sow in December in the warmest spot, and expect a shorter season.
How to plant
- Wait until the soil is warm. Corn will not germinate reliably in cold soil, and a cold, wet spell soon after sowing causes gaps.
- Sow two seeds per hole, 2.5 cm deep and about 30 cm apart, in a block of short rows.
- Water in, then wait until the seedlings appear before watering again.
- Thin to the stronger seedling when they are about 15 cm tall.
- Mulch around the plants to hold moisture.
Watering and feeding
Corn needs plenty of water in hot, dry weather; a deep soak once a week is better than frequent sprinkles. Water steadily from tasselling to when the cobs fill, then ease off as the cobs dry on the plant. Feed with a nitrogen-rich fertiliser when the plants are knee high.
Pruning and care through the year
- Hill soil around the base of the stems as they grow, which helps them stand up to wind.
- Net or bag the cobs if birds start to peck at them.
- Leave the cobs on the plant to dry as long as the weather allows.
Harvesting
Pick when the husks are dry and papery and the kernels are hard and glossy, usually about four months after sowing. Peel back the husks and hang the cobs somewhere dry and airy for a few more weeks to finish drying. Test by popping a few kernels; when they pop well, rub the kernels off the cob and store them in an airtight jar.
Varieties
- Strawberry Popcorn
- Tom Thumb
Companion planting
Corn is the tall member of the traditional corn, beans and squash planting.
Good companions
- Beans Climbing beans use the stalks as support and fix nitrogen.
- Pumpkin Sprawls beneath, shading the soil and smothering weeds.
- Lettuce A quick crop for the gaps while the corn is young.
Keep apart
Avoid planting these close to popcorn.
- Tomato Both are hungry crops, and tomato fruitworm attacks both.
- Sweet Corn Cross-pollination makes sweet corn kernels starchy, so keep the two apart.
Pests and diseases
Corn earworm and birds are the main pests.
Pests to watch for
- Tomato fruitworm Caterpillars feeding in the tips of the cobs under the husk.
- Birds Husks torn open and kernels pecked from drying cobs.
Diseases to watch for
- Rust Small orange-brown pustules on the leaves in late summer.
- Smut Large grey, swollen galls on cobs and stems. Remove and bin them before they burst.
Common questions
Can I grow popcorn next to sweet corn?
It is best not to. They cross-pollinate, which makes the sweet corn kernels starchy and tough. Plant them well apart, or sow them a few weeks apart so they flower at different times.
When is popcorn ready to harvest?
When the husks are dry and papery and the kernels are hard, usually about four months after sowing. Finish drying the cobs indoors for a few weeks.
Why won't my popcorn pop?
It is usually too wet or too dry. Kernels need to be fully mature and dried to the right moisture. Dry the cobs for a few weeks, test a few, and store the kernels airtight.
Why are my cobs only partly filled?
Poor pollination. Corn is wind pollinated, so plant in a block of short rows rather than a single long row.
When should I sow popcorn?
Once the soil is warm, from October in the north and November or December further south. Choose your region at the top of the page.
Sources we checked: Kings Seeds: Corn Popcorn F1; Yates NZ: How to grow corn.