When to plant Broccoli in Tropical Australia

Tropical zone — applies to Darwin, Cairns, Townsville, Broome, Mackay and similar areas. Growing elsewhere? Temperate · Cool · Subtropical · Arid.

Broccoli is a dry-season crop in the tropics: sow direct from April to July, 6 mm deep, once the monsoon has properly finished. Gardeners in Darwin and Mackay treat it as their 'winter' vegetable, using the mild, dry months to grow what southern states plant in autumn. Germination runs 15–25 days and heads take anywhere from 60 to 120 days, so an April or May sowing gives the longest run of cool weather. Pick a quick, heat-tolerant variety and be ready for caterpillars from day one — brassicas here draw the cabbage white butterfly all season.

Sowing calendar — tropical zone

Green months are your sowing window: April to July.

Growing notes

Broccoli belongs entirely to the dry season here. A wet-season attempt collapses under heat stress, root rot and a caterpillar population running at full speed, so hold seed back until April. Within the April–July window, earlier is stronger: with 60–120 days to maturity, an April or May sowing lets heads form through the coolest weeks of June and July, while a late-July sowing risks the plant trying to head up as October heat builds — the classic trigger for 'buttoning', where stressed plants throw tiny premature heads. Once it happens there is no reversing it; pull the plant and sow earlier next year.

Give plants a firm, compost-rich bed with good drainage, spaced 35–45 cm apart in rows 40–60 cm apart, and never let them dry out — dry-season irrigation is non-negotiable for even growth. Mulch heavily to keep roots cool. Cabbage white butterflies stay active around Darwin gardens even in July, so drape fine exclusion netting over hoops from the day you sow and keep it sealed at the edges; it is far more effective than spraying after the eggs are laid. After cutting the central head, leave plants in the ground — most varieties keep producing side shoots for weeks afterwards.

Broccoli at a glance

Companion planting

Grows well with

Marigold: Deters cabbage moth and aphids

Nasturtiums: Trap crop for cabbage white butterfly caterpillars

Marigold: Deters cabbage moth; attracts parasitic wasps

Keep away from

Tomatoes: Brassicas and tomatoes compete for same nutrients; inhibit each other

Tomatoes: Brassicas inhibit tomato growth; compete for nutrients

Strawberries: Brassicas inhibit strawberry growth

Common questions

When do you plant broccoli in the tropics?

Sow direct from April to July. April and May sowings are best, as they give heads the longest stretch of cool dry-season weather to mature in.

Why is my broccoli producing tiny heads?

That is buttoning, caused by heat or water stress. Sow early in the window, mulch well and keep watering absolutely even to prevent it.

Can I grow broccoli in Darwin?

Yes, as a dry-season crop. Sow between April and July, choose a heat-tolerant variety and net against cabbage white butterfly from sowing.

How long does broccoli take to grow?

Expect 60–120 days from sowing to harvest depending on variety, with germination alone taking 15–25 days.

How do I stop caterpillars eating my broccoli?

Fine exclusion netting over hoops, installed at sowing and sealed at the edges, is the most reliable defence against cabbage white butterfly in the tropics.

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