How to grow Potato in New Zealand
Potatoes are a Kiwi staple and one of the most rewarding crops in the home garden, with new potatoes ready for Christmas from a September planting. Start with certified seed potatoes, mound soil up the stems as they grow, and keep an eye out for the tomato/potato psyllid, which has been the biggest change to potato growing in New Zealand since it arrived in 2006.
📖 Our full guide: When to Plant Potatoes in NZ: Growing Potatoes by Region
At a glance
When to sow by region
| Region | When to sow | Regional note |
|---|---|---|
| Northland | August to October | |
| Auckland | August to October | |
| Waikato & Bay of Plenty | August to October | |
| Central North Island | October and November | Frost burns the shoots. Plant from mid October and earth up if a late frost is forecast. |
| Wellington & Lower North Island | August to October | |
| Nelson & Marlborough | August to October | |
| Canterbury | September to January | Plant from Sep and earth up or cover the shoots, as frosts run to mid October. Keep planting through Nov to Jan with steady watering. |
| Otago & Southland | October to January | Plant from Oct and earth up or cover the shoots, as frosts run to late October. Cool summers let you keep planting through Nov to Jan. |
| Central Otago | October to January | Plant from Oct and earth up or cover the shoots, as frosts run into early November. Keep planting through Nov to Jan with steady watering. |
Not to be confused with: Sweet potato, which New Zealanders call kūmara. It belongs to a different plant family, is grown from rooted shoots rather than seed potatoes, and needs a much warmer, longer season.
Where to plant
Choose a sunny spot with loose, well-drained soil, and dig in compost or sheep pellets before planting. Potatoes are hungry but do not want a lot of nitrogen, which gives big leafy tops and fewer tubers.
Rotate your beds. Do not plant potatoes where potatoes or tomatoes grew last season, as they share soil-borne diseases. Clear away volunteer potatoes that come up from last year's missed tubers, because they carry disease and give the psyllid somewhere to breed over winter.
- Northland, Auckland and the Bay of Plenty: plant early varieties from late winter into spring, and keep successive plantings going into early summer. Watch closely for psyllids as the weather warms.
- Central North Island and inland districts: wait until mid October, as frost burns the young shoots. Mound soil over them if a late frost is forecast.
- Canterbury, Otago and Southland: plant from September or October, covering or mounding the shoots while frosts last, and keep planting through to January for a main crop to store over winter.
Choosing a variety
Always plant certified seed potatoes from a garden centre or seed supplier. They are checked for viruses and disease, and unlike supermarket potatoes they have not been treated to stop sprouting.
- Early varieties (about 90 to 100 days): Rocket is the fastest and suits containers; Swift, Cliff's Kidney and Jersey Benne are waxy boiling potatoes for the Christmas table. Early potatoes do not store well, so eat them fresh.
- Main crop varieties (about 130 to 140 days): Agria is a high-yielding all-rounder that stores well; Nadine, Red King and Ilam Hardy are other reliable choices.
- Late varieties such as Moonlight and Desiree take more than 140 days and give big crops for winter storage.
- Taewa, the Māori potatoes such as Urenika, Moemoe and Huakaroro, have been grown in New Zealand for more than 200 years and are still sold as seed for home gardens.
How to plant
- About a month before planting, lay the seed potatoes in trays in a light, airy spot out of direct sun until the sprouts are 2 to 4 cm long. This is called chitting.
- Dig a trench or holes 10 to 15 cm deep in well-prepared soil.
- Set the seed potatoes about 30 cm apart with the sprouts facing up, cover with soil and water in.
- As the shoots appear, draw soil, compost or straw up around them. Keep mounding until the mound is about 30 cm high. This protects the shoots from wind and frost and stops tubers turning green.
- For a long harvest, plant a few early varieties in spring and follow with main crop varieties through to late January.
Watering and feeding
Potatoes need steady moisture once the tubers start to form, which is roughly when the plants begin to flower. Water deeply each time you mound them and during dry spells, and ease off as the tops start to yellow and die back. Uneven watering gives knobbly or split tubers.
Feed with a potato or vegetable fertiliser that is higher in phosphorus and potassium than nitrogen. Apply it at planting and every three to four weeks while the plants are growing strongly.
Pruning and care through the year
- Keep mounding until the plants are about 30 cm tall. Any tuber that sees light turns green, and green potatoes are poisonous, so never eat them.
- Check the undersides of leaves weekly from late spring for psyllids: tiny cicada-like adults, flat scale-like nymphs and white sugary granules on the leaves.
- Fine insect mesh laid over hoops from planting keeps psyllids off. Trials in New Zealand found that fully covering the crop with mesh kept psyllids out, which sprays cannot fully do.
- Pull out and bag any plant with yellowing, curled tops and a pink tinge to the leaf edges, which are the signs of psyllid yellows.
Harvesting
Dig early varieties for new potatoes when the flowers are fully open, about three months after planting. Some early varieties, including Rocket, Swift and Nadine, have few or no flowers, so feel gently under the plant for tubers. You can take a few at a time and leave the rest growing.
Lift main crop and late varieties once the tops have yellowed and died back. If the skin rubs off easily with your thumb, the potatoes will not keep, so eat those first. Dry the rest off on a dry day and store them in a cool, dark, airy place, away from light. Dig up every tuber you can find so none are left to sprout next season.
Growing in pots
Potatoes grow well in large pots, planter bags and old buckets with drainage holes. Half fill with potting or vegetable mix, set one or two seed potatoes on top and cover with 10 to 15 cm of mix. Keep topping up the mix as the shoots grow, and water regularly, as containers dry out quickly. Early varieties such as Rocket and Swift suit containers best.
Companion planting
Potato companions are mostly about using space and bringing in helpful insects. Keeping potatoes away from their close relatives matters more, because they share late blight and the psyllid.
Good companions
- Beans Bush beans fit between rows and do not compete much for food.
- Sweet Corn Tall and shallow rooted, so it can share a bed edge without shading the potatoes much.
- Nasturtium Edges the bed and draws aphids away from crops.
- Marigold Flowers bring in hoverflies, whose larvae eat aphids.
Keep apart
Avoid planting these close to potato.
- Tomato Same family. Tomatoes share late blight and the tomato/potato psyllid, so keep them in a different bed and do not follow one with the other.
- Capsicum Another member of the potato family that hosts the psyllid and shares diseases.
- Eggplant Same family, same pests and diseases.
- Pumpkin A sprawling vine that smothers potato plants and competes for space and water.
- Cucumber Competes for space and water, and is usually grown in a separate summer bed.
Pests and diseases
The tomato/potato psyllid is the most serious potato pest in New Zealand. Late blight is the main disease in warm, wet weather. Rotation, certified seed and clearing volunteer plants help with both.
Pests to watch for
- Tomato/potato psyllid Tiny jumping insects and flat yellow-green nymphs under the leaves, with white sugary granules. Plants yellow at the tips, leaves curl with a pink edge, and tubers stay small and show dark stripes when cooked (zebra chip).
- Aphids Clusters of small green or pink insects on shoots and under leaves. They spread potato viruses.
Diseases to watch for
- Late blight Dark, greasy patches on leaves and stems that spread fast in warm, humid weather, often with white growth under the leaf. Cut off and bin the tops. The tubers can usually still be eaten, but will not store. Early varieties are less often hit than main crops.
- Early blight Brown spots with target-like rings on older leaves, usually later in the season.
Common questions
When do I plant potatoes for Christmas in New Zealand?
Plant an early variety such as Rocket or Swift in September. They take about 90 days, so a September planting is ready by Christmas. Jersey Benne takes a couple of weeks longer, so get it in early in September.
Can I plant potatoes from the supermarket?
It is better not to. Supermarket potatoes are not certified free of virus and disease, and they are often treated to stop them sprouting. Certified seed potatoes give a cleaner, bigger crop.
What is chitting?
Chitting means sprouting seed potatoes before you plant them. Lay them out in trays in a light, airy place out of direct sun for about a month, until the shoots are 2 to 4 cm long.
How do I protect potatoes from psyllid?
Cover the plants with fine insect mesh on hoops from planting, check the undersides of the leaves often, remove volunteer potatoes over winter, and pull out and bag any plants with psyllid yellows.
Why are my potatoes green?
The tubers have been exposed to light. Green potatoes contain a toxin, so cut away green parts or throw them out. Keep mounding soil over the plants as they grow, and store potatoes in the dark.
What are the dark stripes inside my potatoes?
That is zebra chip, caused by a bacterium spread by the tomato/potato psyllid. The stripes darken when the potatoes are fried, and infected tubers go mushy when boiled. Control the psyllid next season with mesh covers and good hygiene.
Can I grow potatoes in a bag or pot?
Yes. Use a large planter bag or pot with drainage, half fill it with mix, plant one or two seed potatoes and keep topping up the mix as the shoots grow. Early varieties suit containers best.
Sources we checked: Tui: Top potato tips; Yates NZ: How to grow potatoes; Kings Plant Barn: Our guide to potato varieties; Plant & Food Research: Controlling the tomato/potato psyllid in the home garden; Merfield: Tomato potato psyllid management with mesh crop covers (2012).