How to grow Broccoli in New Zealand
Broccoli is one of the most rewarding brassicas: cut the big central head and the plant keeps sending up side shoots for weeks. It does best in cool weather, so the main crop is planted from late summer into autumn, but heat-tolerant varieties allow spring and summer crops too. Insect mesh against white butterfly is the key to clean heads.
📖 Our full guide: When to Plant Broccoli in NZ: How to Grow Broccoli by Region
At a glance
When to sow by region
| Region | When to sow | Regional note |
|---|---|---|
| Northland | August to October, January to April | |
| Auckland | August to October, January to April | |
| Waikato & Bay of Plenty | August to October, January to April | |
| Central North Island | August to October, January to April | |
| Wellington & Lower North Island | August to October, January to April | |
| Nelson & Marlborough | August to October, January to April | |
| Canterbury | August to November, January to April | Sow Aug to Nov and Jan to Apr. Cover early sowings with a cloche or frost cloth, as frosts run to mid October. Get the last sowing in by Apr so it sizes up before winter growth stops. |
| Otago & Southland | September to April | Sow Sep to Apr. Cover early sowings with a cloche or frost cloth, as frosts run to late October. Get the last sowing in by Apr so it sizes up before winter growth stops. |
| Central Otago | September to April | Sow Sep to Apr. Cover early sowings with a cloche or frost cloth, as frosts run to early November. Get the last sowing in by Apr so it sizes up before winter growth stops. |
Where to plant
Plant broccoli in full sun in fertile, well-drained soil enriched with compost. Broccoli and other brassicas are prone to clubroot, a soil-borne disease, so plant them in a different bed each year and do not return to the same bed for at least three years. Lime acid soils before planting.
- Northland, Auckland, Waikato and Bay of Plenty, the central North Island, Wellington, and Nelson and Marlborough: sow from January to April for autumn and winter crops, and from August to October for spring and early summer crops. Use a heat-tolerant variety for spring sowings.
- Canterbury: sow from August to November and January to April, covering early sowings with a cloche or frost cloth, as frosts run to mid October. Get the last sowing in by April.
- Otago and Southland and Central Otago: sow from September to April, covering early sowings, and get the last sowing in by April so plants size up before winter growth stops.
Choosing a variety
- Summer Green: a heat-tolerant, uniform heading broccoli for sowing from spring to late summer. Sow a few every fortnight.
- Winter Green: cold tolerant, with well-domed heads for autumn and winter. Sow from late summer to late autumn and do not overfeed with nitrogen.
- Sprouting broccoli such as Winter Rudolph: purple florets on tender stems, picked over 3 to 5 weeks.
- Tasty Stems: a sprouting type similar to broccolini; pinch out the central head when it is the size of a $2 coin for more shoots.
How to plant
- Sow seed about 6 mm deep in trays of seed raising mix, or direct.
- Keep moist; seedlings appear in 5 to 10 days.
- Transplant at about 4 to 6 weeks, 40 to 45 cm apart, into soil enriched with compost or blood and bone.
- Water in and cover the bed with fine insect mesh straight away to keep white butterflies and diamondback moths off.
- Mulch to keep the soil moist.
Watering and feeding
Water regularly so growth never checks, as stressed plants form small, early heads. Mulch to hold moisture.
Feed every couple of weeks with a liquid fertiliser for leafy vegetables while plants are growing. Avoid heavy nitrogen for winter varieties.
Pruning and care through the year
- Keep insect mesh on while white butterfly and diamondback moth are active, from spring to autumn.
- Stake tall plants in windy gardens.
- After harvest, pull out spent plants and rotate the next brassica crop to another bed.
Harvesting
Cut the central head while the buds are still tight and green, before any yellow flowers open, taking about 15 cm of stem. Removing it makes the plant send up smaller side shoots, ready to pick in a few weeks. Keep cutting these regularly.
Broccoli grows slowly in the cool months and can take 16 to 20 weeks from sowing in winter. It keeps up to five days unwrapped in the fridge crisper, and blanches and freezes well.
Growing in pots
One broccoli plant can grow in a pot at least 40 cm wide and deep, filled with quality potting mix. Keep it well watered and fed, and cover it with insect mesh. Sprouting varieties give more picking from one pot.
Using it
The heads, stems and tender leaves can all be eaten. Steam, stir-fry or roast the florets, peel and slice the stems, and use young leaves like kale.
Companion planting
Aromatic herbs and flowers around broccoli bring in beneficial insects.
Good companions
- Beetroot Fills the gaps between young broccoli plants without competing.
- Onion A slim crop that fits between broccoli rows.
- Celery Likes the same cool, moist, fertile conditions.
- Dill Its flowers attract parasitic wasps and hoverflies that prey on caterpillars and aphids.
- Rosemary A strongly scented herb traditionally planted near brassicas.
- Sage Another aromatic herb traditionally grown near brassicas.
- Chamomile Its flowers bring in beneficial insects.
- Nasturtium Draws aphids and some caterpillars away from the crop.
Keep apart
Avoid planting these close to broccoli.
- Tomato A summer crop that shades broccoli and wants different conditions.
- Strawberry Traditionally kept away from cabbage family crops.
- Climbing beans Traditionally kept away from brassicas, and they shade the bed.
Pests and diseases
Caterpillars are the main problem, and insect mesh is the best answer.
Pests to watch for
- White butterfly Green caterpillars and ragged holes in leaves, and caterpillars hidden in the heads.
- Diamondback moth Small green caterpillars that wriggle when touched, and leaves with small holes and windows.
- Aphids Grey, waxy colonies under leaves and in the heads, with distorted growth.
- Slugs Seedlings chewed and silvery slime trails.
- Snails Large, ragged holes in leaves after damp nights.
Diseases to watch for
- Clubroot Plants wilt on warm days and the roots are swollen and distorted. Rotate beds over at least three years and lime acid soil.
- Downy mildew Yellow patches on the upper leaf with grey fuzz underneath, mostly on seedlings in cool, damp weather.
Common questions
When should I plant broccoli in New Zealand?
The main crop is sown from January to April for autumn and winter heads. You can also sow from August to October for spring and early summer, using a heat-tolerant variety such as Summer Green.
Why is my broccoli flowering before it forms a head?
Stress, usually heat or dry soil, makes broccoli bolt or form small early heads. Keep it well watered and choose varieties for the season.
Will broccoli grow back after cutting?
Yes. After the main head is cut, the plant sends up smaller side shoots for several weeks. Keep cutting them regularly.
How do I keep caterpillars off broccoli?
Cover the plants with fine insect mesh from planting, so white butterflies and diamondback moths cannot lay eggs on them.
Why are my broccoli plants wilting on hot days?
Check the roots for swellings. That is clubroot, a soil-borne disease. Do not grow brassicas in that bed for at least three years.
How long does broccoli take to grow?
About 60 to 80 days from transplanting in warm weather. In winter it grows slowly and can take 16 to 20 weeks from sowing.
Sources we checked: Yates NZ: How to grow broccoli; Yates NZ: Common problems of broccoli; Kings Seeds: Broccoli Summer Green F1; Kings Seeds: Broccoli Winter Green F1; Kings Seeds: Broccoli Sprouting Winter Rudolph; Kings Seeds: Broccoli Tasty Stems F1.