How to Grow Zucchini in New Zealand

Updated June 2026

Zucchini (the same plant the British and French call courgette) is one of the most productive crops you can grow. Sow direct from October once frost has passed in the warm north, or raise seedlings inside in cooler regions. One or two plants is usually plenty. Pick young and often to keep them producing, and water at the base to keep powdery mildew at bay.

What it looks like as it grows

Position and soil

Zucchini wants full sun and rich, well-fed soil. It is a hungry, thirsty plant. Dig in plenty of compost and aged manure before planting so the bed holds moisture and feeds the plant through a long season. Good drainage matters too, so a raised mound or bed suits it well.

When to plant zucchini in New Zealand

Timing matters here, where the warm north and the cooler south are weeks apart. Zucchini needs warm soil of around 18 degrees Celsius, so wait until frost has passed. Sow or plant in these months for your region:

Sowing and planting

Build a planting mound or hill by mixing compost and aged manure into the soil. Mounds drain well and warm faster in spring. Sow 2 to 3 seeds per mound, around 2 cm deep, and thin to the single strongest seedling once they have a couple of true leaves. Seeds germinate in about 7 days, and plants are ready to harvest in roughly 60 days. In cooler regions, raise seedlings inside 3 to 4 weeks before your last frost and transplant once the weather settles.

Spacing

Give each plant room. Space bush varieties 80 to 100 cm apart, roughly one square metre per plant. They grow into large, sprawling plants, and good spacing keeps air moving through the leaves, which is your first defence against powdery mildew. Climbing types such as Tromboncino can be trained up a trellis to save ground space.

Watering and feeding

Zucchini are heavy feeders and need consistent water. Water deeply at the base of the plant, never over the leaves, and keep the soil evenly moist rather than swinging between dry and soaked. Mulch around the base to hold moisture. Feed every two to three weeks with a balanced liquid fertiliser once flowering starts to keep the fruit coming.

Pollination

Zucchini produce separate male and female flowers on the same plant. Male flowers appear first on thin, straight stems. Female flowers have a small swelling, the baby courgette, behind the petals. Bees move pollen from male to female. If a female flower is not pollinated, the small fruit behind it yellows, shrivels at the blossom end, and drops off. This poor fruit set is the most common complaint and is often mistaken for disease.

To hand pollinate, pick a male flower, peel back the petals, and dab the pollen-covered stamen onto the stigma in the centre of a female flower. Do it in the morning when the flowers are freshly open.

Best zucchini varieties for NZ

Companion planting

Grow zucchini near nasturtium, corn, beans, and marigold. Flowers nearby draw in the bees that pollinate your fruit.

Pests and problems

Powdery mildew

White powder over the leaves is almost guaranteed by late summer. Water at the base, improve airflow with good spacing, and remove the worst leaves. A weekly spray of one part milk to nine parts water can slow it. See our powdery mildew guide.

Fruit rotting at the tip

Tiny fruit that rots and drops at the blossom end is poor pollination, common in cool or wet spells. Hand pollinate with a male flower, or wait for the bees in better weather.

28-spotted ladybird and aphids

The 28-spotted ladybird and its larvae skeletonise leaves into a lacy look; pick them off by hand. Aphids and whitefly cluster on soft growth; hose them off and encourage predators. See our NZ pest and disease guide for organic control.

Harvesting

Pick zucchini young at 15 to 20 cm for the best flavour, and check plants every two days during peak production. Fruit grows fast and can double in size overnight. Leave it too long and you get a marrow: watery, tough-skinned, and full of seeds, which also slows down new fruit. Cut the stem cleanly with a sharp knife rather than pulling.