When to plant Watermelon in Tropical Australia

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

Watermelon loves tropical heat, and you can sow it direct from February to November — the dry season is ideal, as fruit ripens best without constant rain. Seed germinates in 6 to 18 days in warm soil, and fruit is ready in anywhere from 70 to 120 days depending on the variety. Sow deep, around 15 to 20 mm, and give the sprawling vines room, with rows 150 to 180 cm apart.

Around Broome and Townsville, watermelon is a standout dry-season crop, thriving in the warmth and long sun that would stress leafy greens. The main task is drainage and space — plant into free-draining ground and time sowing so fruit sweetens through the drier months rather than the monsoon.

Sowing calendar — tropical zone

Green months are your sowing window: February to November.

Growing notes

Season timing is everything for tropical watermelon. Aim to have vines fruiting through the dry season, when lower humidity and reliable sun concentrate sugars and hold fungal disease at bay — a sowing from around April to July in the Mackay and Darwin districts sets fruit up to ripen in the driest, brightest part of the year. Fruit swelling during heavy monsoon rain tends to be watery, bland, or prone to splitting and rot.

Give watermelon full sun and deep, free-draining soil enriched with compost, on mounds if your ground stays wet. The vines are heavy feeders and drinkers while growing, so water generously early on, then ease back as fruit approaches ripeness to intensify the flavour. Powdery mildew and fungal leaf disease are the main threats in humid spells, so water at the base, keep foliage dry, and space vines widely for airflow.

A frequent frustration is flowers that never set fruit. Watermelon carries separate male and female flowers and relies on bees to move pollen between them, so poor set usually means few pollinators — if fruit is not forming, hand-pollinate in the early morning. Rest ripening fruit on a tile or board to keep it off damp soil and away from rot.

• Sow to ripen through the dry season
• Plant on mounds for drainage
• Space rows 150 to 180 cm for the sprawling vines
• Ease back on water as fruit ripens for sweetness
• Hand-pollinate if bees are scarce

Watermelon at a glance

Common questions

When should I plant watermelon in the tropics?

Sow across February to November, aiming for fruit to ripen through the dry season. An April to July sowing lets melons sweeten in the driest, sunniest months.

Can I grow watermelon in Broome?

Yes, Broome's hot, sunny dry season suits watermelon very well. Plant into free-draining soil and give the vines plenty of room to run.

Why are my watermelon flowers not setting fruit?

The plant has separate male and female flowers and needs bees to pollinate. If set is poor, hand-pollinate in the early morning by transferring pollen from a male flower to the females.

Keep exploring