When to plant Bean (Bush) in Tropical Australia

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

Bush beans sow direct in every month of the year in the tropical zone and are arguably the easiest legume from Darwin to Townsville. Seed goes in 20–30 mm deep, germinates in a brisk 7–15 days, and pods arrive 50–80 days later — quick enough to fit several crops into a single dry season. Frost tenderness is irrelevant here; the real divide is wet versus dry, and while beans will grow through the monsoon, rust and bean fly make the dry season the low-stress choice. Sow a short row every three or four weeks rather than one glut.

Sowing calendar — tropical zone

Green months are your sowing window: January to December.

Growing notes

Dry-season bush beans (May to October) are close to foolproof: steady warmth, low disease pressure and a quick turnaround. Wet-season sowings still crop, but you are managing two enemies. The first is fungal — bean rust and pod rots thrive in monsoon humidity, so space plants at the full 7–15 cm in rows 40–60 cm, orient rows to catch the breeze, water at soil level in the morning and never handle plants while foliage is wet, which spreads spores. The second is bean fly, a genuine tropical pest whose larvae tunnel seedling stems until plants wilt and snap at ground level; it is worst in warm, humid weather. Hilling soil up around stems encourages roots above the damage, and sowing more thickly than you need lets you afford casualties.

Beans fix their own nitrogen, so skip nitrogen-rich fertiliser — overfed plants make leaves instead of pods. A well-drained bed with compost and a little potash is enough. The commonest failure in Darwin and Townsville gardens is flower drop without pod set during the extreme heat and humidity of the build-up (October to December); either wait it out, as plants usually reset when conditions ease, or time sowings so flowering avoids the steamiest weeks. Pick pods young and often — twice a week — because leaving pods to fatten shuts production down.

Bean (Bush) at a glance

Companion planting

Grows well with

Marigold: Deters Mexican bean beetle

Carrot: Beans fix nitrogen; carrots benefit from improved soil

Marigold: Deters Mexican bean beetle

Keep away from

Garlic: Alliums stunt legume growth by inhibiting nitrogen-fixing bacteria

Onion: Alliums inhibit nitrogen-fixing bacteria essential to beans

Shallots: Alliums inhibit bean growth

Common questions

When do you plant bush beans in the tropics?

Any month of the year, though May to October sowings are the easiest. Sow a short row every three or four weeks for a continuous supply.

Why are my bean seedlings wilting and snapping at the base?

That is bean fly, whose larvae tunnel through seedling stems. Hill soil up around the stems to encourage new roots and sow extra seed to cover losses.

Do bush beans grow in the Darwin wet season?

Yes, but expect rust and bean fly pressure. Give plants full spacing, water at soil level in the morning and avoid touching wet foliage.

Why do my beans flower but set no pods?

Extreme heat and humidity, typical of the build-up months, cause flower drop. Plants usually set again when conditions ease, or you can time sowings to flower in milder weather.

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