How to grow Squash in New Zealand
Summer squash, such as the scalloped button or scallopini types, are quick, productive relatives of the zucchini that can be picked within six to seven weeks of planting. Sow them once the soil is warm, give them sun, rich soil and steady water, and pick them small and often. Long-keeping winter squash such as buttercup and butternut are grown like pumpkins.
📖 Our full guide: How to Grow Squash 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 and December | |
| 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: Pumpkin and zucchini. In New Zealand, buttercup and butternut squash are usually grown and stored like pumpkins, while summer squash and zucchini are picked young.
Where to plant
Grow squash in full sun in well-drained soil enriched with compost or blood and bone. Compact bush types suit raised beds, while vining types need room to sprawl or a trellis. Avoid beds where pumpkins, zucchini, cucumbers or melons grew last season.
- Northland, Auckland, Waikato and the Bay of Plenty: sow direct from October once the soil is warm.
- Central North Island, Wellington, Nelson and Canterbury: sow or plant in November and December.
- Otago, Southland and Central Otago: wait until December, or start seed indoors and plant out once frosts are over.
Choosing a variety
- Scallopini and button squash are flattened, scalloped summer squash, best picked small, and bush types suit small gardens.
- Mixed summer squash packets give a range of shapes and colours from the same sowing.
- For storing over winter, grow buttercup, butternut or Kumi Kumi, and treat them like pumpkins.
How to plant
- Make small mounds of enriched soil about 70 cm apart.
- Sow three or four seeds in each mound and water well.
- As the seedlings grow, thin to the two strongest plants in each mound.
- Mulch with pea straw to hold moisture and keep the fruit clean.
Watering and feeding
Water regularly, especially in hot or windy weather, and water the soil rather than the leaves. Water sitting on the foliage encourages powdery mildew. Uneven watering can also cause blossom end rot on the fruit.
Feed weekly with a liquid fertiliser such as fish and seaweed, or every few weeks with a vegetable food.
Pruning and care through the year
- Pick regularly. Leaving fruit to grow big slows the plant down, while frequent picking keeps flowers and fruit coming.
- If fruit starts to form and then shrivels, pollination is poor. Hand pollinate early in the morning by brushing a male flower onto the centre of a female flower, which has a tiny swollen fruit behind it.
- Remove leaves badly affected by mildew to keep air moving.
Harvesting
Harvest summer squash young, while the skin is still soft and the fruit is small. Cut them off with a short piece of stem. Check plants every couple of days in summer, as fruit grows quickly.
Growing in pots
Bush squash grow well in a pot at least 40 cm wide and deep in full sun. Sow three or four seeds, thin to the strongest plant, feed weekly and water often.
Companion planting
Squash share the traditional corn, beans and squash planting, and benefit from flowers that bring in bees.
Good companions
- Sweet Corn Tall and upright, so it shares the bed without competing for ground space.
- Beans Fix nitrogen and fit around squash in a three sisters bed.
- Borage Its flowers bring in bees, which squash needs for pollination.
- Nasturtium Draws aphids and brings in pollinators.
- Marigold Brings in hoverflies and bees.
Keep apart
Avoid planting these close to squash.
Pests and diseases
Powdery mildew is the main problem from mid summer. Good spacing, base watering and regular feeding keep plants cropping.
Pests to watch for
- Aphids Clusters of small insects under leaves; they spread viruses that mottle the leaves.
- Whitefly Tiny white insects fly up from the undersides of leaves.
- Slugs and snails (slugs and snails) Seedlings eaten off at soil level.
Diseases to watch for
- Powdery mildew White, powdery patches on the leaves, spreading in dry, warm weather.
- Downy mildew Yellow patches on top of leaves with grey growth underneath in humid weather.
- Blossom end rot The flower end of the fruit turns dark and soft, linked to uneven watering.
Common questions
How long until I can pick squash?
Summer squash are quick: you can be picking six to seven weeks after planting.
Why are my baby squash rotting and falling off?
Usually the flowers were not pollinated, often in cool or wet weather when bees are few. Hand pollinate early in the morning and grow flowers nearby to bring in bees.
When should I pick button squash?
Small and young, while the skin is still soft and shiny. The more often you pick, the more the plant produces.
Is buttercup a squash or a pumpkin?
Both names are used in New Zealand. Buttercup is a winter squash that is grown, cured and stored like a pumpkin.
Can I grow squash in a pot?
Yes, compact bush types grow well in a pot at least 40 cm wide and deep, in full sun with regular feeding and watering.
Sources we checked: Yates NZ: How to grow squash; Tui: Courgette growing guide; Kings Seeds: Squash Kumi Kumi.