When to plant Squash in Subtropical Australia

Subtropical zone — applies to Brisbane, Gold Coast, Sunshine Coast, Coffs Harbour, Lismore and similar areas. Growing elsewhere? Temperate · Cool · Tropical · Arid.

Sow squash direct once the soil is warm, from August to March, avoiding the coldest weeks. Drop two or three seeds per station 15–25 mm deep and thin to the strongest, spacing plants 60–100 cm apart in rows 90–100 cm apart, as these are hungry, sprawling plants. Seed germinates fast in warm soil, in 6–18 days, and quick varieties crop from 50 days, with others up to 90. In Brisbane and the Gold Coast, the spring and late-summer sowings dodge the worst of the wet season, when mildew and fruit rot are at their most punishing.

Sowing calendar — subtropical zone

Green months are your sowing window: August to March.

Growing notes

Squash grows vigorously in subtropical warmth, but the humid summer brings the two failures that trouble every grower from Brisbane to Coffs Harbour: powdery mildew and poor fruit set. Mildew coats the leaves in white bloom and shuts down the plant, while wet, still mornings limit the bee activity needed to pollinate the flowers, so young fruit yellows and rots at the tip.

Tackle mildew with airflow and dry foliage: honour the wide spacing, water at the base early in the day, and remove the oldest affected leaves. If bees are scarce during the wet, hand-pollinate by brushing a male flower into the open female flowers in the morning.

Nasturtiums make a useful companion here, deterring squash bugs and drawing aphids away as a trap crop, so let them sprawl at the edge of the patch.

A few more subtropical pointers:

• Feed richly; squash is a heavy feeder and rewards compost-rich beds.
• Harvest young and often, as leaving fruit to mature slows further production.
• Mulch to keep fruit off wet soil and reduce rot during rainy spells.

Stagger sowings a few weeks apart so a single mildew wave does not wipe out your whole supply at once.

Squash at a glance

Companion planting

Grows well with

Nasturtiums: Deters squash bugs; trap crop for aphids

Common questions

why is my squash covered in white powder?

That is powdery mildew, which thrives in the humid subtropical summer. Improve airflow by honouring the 60–100 cm spacing, water at the base early in the day, and strip off the worst-affected old leaves. Staggered sowings also limit the damage.

why are my squash fruit rotting before they grow?

Poor pollination. During wet, still subtropical mornings bees are less active, so female flowers go unfertilised and the tiny fruit yellows and rots. Hand-pollinate by brushing a male flower into the female flowers early in the day.

when can I sow squash in Brisbane?

Sow from August to March, favouring spring and late summer to sidestep the wettest weeks. Warm soil brings fast germination in 6–18 days, and quick varieties can crop in as little as 50 days.

do nasturtiums really help squash?

Yes. Nasturtiums help deter squash bugs and act as a trap crop that draws aphids away from your squash. Let them sprawl around the edge of the patch where they will not shade the main plants.

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