When to plant Brussels Sprouts in Tropical Australia

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

Brussels sprouts can be sown direct from February to April in tropical Australia, but be clear-eyed: this is the most marginal brassica for the zone. The early window is pure arithmetic — at 80–140 days to maturity, a February or March sowing has sprouts forming through June and July, the only months cool enough to firm them. Seed goes just 6 mm deep and seedlings appear within a fortnight, then plants need generous room at 50–75 cm apart in rows 90 cm apart. Coastal growers in Townsville or Mackay should treat the crop as an experiment; on the Atherton Tablelands it becomes a genuine one.

Sowing calendar — tropical zone

Green months are your sowing window: February to April.

Growing notes

Everything about tropical Brussels sprouts is about buying cool nights. Sow in February or March even though the wet is still running — into a mounded, free-draining bed, with a shadecloth tent handy to shield seedlings from a late monsoon downpour. An April sowing looks easier but pushes maturity into September's warmth, and warm-finished plants produce "blown" sprouts: loose, leafy rosettes instead of tight buttons. That is the classic failure here, and there is no rescue once it starts — harvest whatever formed early while it is small and firm, and eat the leafy top like a loose cabbage.

Cabbage white butterfly pressure is relentless in the tropics because the population never gets a cold-season knockdown. Cover the bed with fine exclusion netting from sowing day and keep the edges sealed; weekly egg checks are the backup, not the plan.

• Feed fortnightly with a nitrogen-rich liquid feed until sprouts begin forming, then stop
• Firm soil around stems and hill lightly — top-heavy plants lean in gusty dry-season winds
• Strip the lower leaves as sprouts develop to improve airflow
• Water deeply twice a week rather than a daily splash

Pick from the bottom of the stalk upward as each sprout reaches golf-ball size, and finish the harvest before the build-up arrives.

Brussels Sprouts at a glance

Companion planting

Grows well with

Nasturtiums: Trap crop for cabbage white butterfly

Sage: Reduces diamondback moth pressure

Sage: UMN Extension research: reduces diamondback moth pressure

Common questions

When should I sow Brussels sprouts in tropical Australia?

Sow direct from February to April, and earlier is better. February–March sowings mature through the coolest months of June and July, which sprouts need to form tight heads.

Why are my Brussels sprouts loose and leafy instead of firm?

They matured in warm weather — sprouts "blow" open when night temperatures are too high. Sow earlier in the window so plants finish in mid-winter, and harvest sprouts small.

Can I grow Brussels sprouts in Mackay?

You can try — sow in February or March and treat it as an experiment, since coastal warmth often blows the sprouts open. Elevated districts inland do noticeably better.

Do Brussels sprouts need frost to taste good?

No. Frost sweetens them in cold climates, but the real requirement is cool nights during maturity — which is why timing the crop into June and July matters in the tropics.

How do I stop caterpillars eating my Brussels sprouts?

Cabbage white butterfly is the main culprit and it is active year-round in the tropics. Fine exclusion netting fitted from sowing day, sealed at the edges, is the most reliable control.

Keep exploring