How to grow Zucchini in New Zealand

Where to plant

Courgettes want a hot, sunny spot with at least six hours of sun, sheltered from strong wind, in moist but free-draining soil. Dig in compost a week or two before planting and mound the soil slightly for drainage. They spread wide, so give them room, and rotate them with other crops each season.

• Northland, Auckland, Waikato and the Bay of Plenty: plant from late October once the soil has warmed. Seed can be started indoors from September.
• Central North Island, Wellington, Nelson and Canterbury: wait until November, when frosts are usually past, and keep planting into December.
• Otago, Southland and Central Otago: plant in December, or start seed indoors and plant out once frosts are over.

Choosing a variety

• Green: Blackjack and Black Beauty are classic dark green courgettes that crop heavily; Black Coral is an early hybrid.
• Yellow: Gold Rush has bright golden fruit with a mild, sweet flavour.
• Striped and ribbed: Cocozelle and Costata Romanesco are Italian heirlooms with rich, nutty flavour.
• Climbing types such as Tromboncino or Rampicante grow up supports and save ground space.
• Compact bush varieties are best for pots.

How to plant

1. To get ahead, sow seed indoors in warmth from September, and transplant when seedlings are about 5 cm tall with a few leaves, after hardening them off for a week or so.
2. Outdoors, sow three or four seeds into a mound of moist soil and thin to the strongest plant, or plant seedlings 80 cm to 1 m apart.
3. Plant in the early morning or late afternoon and water well before and after planting.
4. Mulch around the plants to hold moisture and keep the fruit clean.

Watering and feeding

Courgettes grow fast and need a steady water supply. Keep the soil evenly moist without letting it dry out completely, but avoid waterlogging. Uneven watering causes odd-shaped fruit and blossom end rot. Water the soil, not the leaves.

Courgettes are not heavy feeders if the soil was well prepared. Feed lightly once fruit starts to form, or use a liquid seaweed feed every week to ten days. Too much fertiliser gives big leaves and few courgettes.

Pruning and care through the year

• Courgettes have separate male and female flowers. If fruit shrivels without growing, pollination is poor: hand pollinate early in the morning by brushing a male flower onto a female one, which has a tiny fruit behind it.
• Grow marigolds, borage or calendula nearby to bring in bees.
• Remove older leaves at the base to improve air flow, and remove leaves badly hit by powdery mildew.
• Keep the bed weed free.

Harvesting

Pick courgettes young and tender, before they turn into marrows. In warm weather a fruit can be ready two or three days after flowering, so check plants every few days. Regular picking keeps the plants producing right through the season.

The male flowers can be picked for stuffing and frying. Grate and freeze any surplus, squeezing out the moisture first.

Growing in pots

Choose a compact variety and a pot or trough at least 40 cm wide and deep, filled with vegetable or potting mix. Place it in full sun out of strong wind, water often and feed lightly but regularly.