How to Grow Watermelon in Australia
Ripeness testing, variety picks, and planting calendars for every region
Watermelon is the ultimate summer crop. Nothing beats cracking open a sun-warmed melon you grew yourself. They need space, heat, and patience, but the growing itself is straightforward. If you can grow pumpkins, you can grow watermelons.
This guide covers the best varieties for Australian conditions, how to tell when a melon is actually ripe, pollination tips, and regional planting times.
When to Plant in Your Region
Sugar Baby
Compact variety producing round, dark-green melons weighing 3 to 5 kg. Sweet red flesh. The best choice for smaller gardens and cooler regions because it matures faster (10 to 12 weeks) than large varieties.
Crimson Sweet
Classic large watermelon with striped skin and deep red, sweet flesh. Fruit weigh 8 to 12 kg. Needs a long, hot season. Best in subtropical and tropical regions or warm-temperate areas with long summers.
Moon and Stars
Stunning heirloom with dark green skin splashed with yellow spots. Sweet, flavourful flesh. A heritage variety worth growing for its beauty alone. Medium-sized fruit around 6 to 8 kg.
Yellow Baby
Small, round melons with bright yellow flesh and a delicate, honey-sweet flavour. A surprise at the table. Compact vines suit smaller gardens. Matures in 10 to 12 weeks.
Charleston Grey
Large, elongated watermelon with pale grey-green skin. Thick rind resists cracking. Excellent for hot climates. Fruit can weigh 10 to 15 kg in good conditions. One of the best varieties for tropical regions.
Ripeness Testing
Knowing when a watermelon is ripe is the trickiest part. Once picked, they do not ripen further. Here are the reliable tests:
- Ground spot: The patch where the melon rests on the ground should be creamy yellow, not white or pale green
- Tendril test: The curly tendril nearest the fruit stem dries out and turns brown when the melon is ripe
- Thump test: A ripe melon sounds hollow when tapped. An unripe one sounds dull and solid
- Skin texture: The skin loses its shine and becomes slightly dull when ripe
Pollination
Watermelons have separate male and female flowers on the same vine. Male flowers appear first. Female flowers have a tiny melon shape behind the petals. Bees do most of the pollination work.
If fruit is not setting, pollination may be poor. Hand-pollinate in the morning by picking a male flower, removing the petals, and rubbing the pollen onto the centre of a female flower. Each female flower is only receptive for one day.
Growing Method
- Prepare a mound. Watermelons need excellent drainage. Build mounds of compost-enriched soil about 30 cm high and 1 metre across. Space mounds 2 to 3 metres apart.
- Sow 2 to 3 seeds per mound. Plant seeds 2 cm deep. Thin to the strongest seedling once they have 2 true leaves.
- Mulch heavily. Black plastic mulch or thick straw keeps soil warm, retains moisture, and keeps fruit clean.
- Water deeply but infrequently. Deep watering encourages deep roots. Reduce watering as fruit approaches maturity to concentrate sugars and prevent splitting.
- Feed with potassium-rich fertiliser once fruit begins to swell. Avoid high nitrogen which produces vines at the expense of fruit.
Common Problems
Splitting
Fruit cracks open, usually after heavy rain or overwatering when the melon is nearly ripe. Reduce watering in the last 2 weeks before harvest.
Powdery mildew
White coating on leaves late in the season. Spray with milk solution (1 part milk to 9 parts water). Good air circulation helps prevent it.
Fruit fly
A serious pest in tropical and subtropical regions. Use fruit fly netting or traps. Monitor from the moment fruit begins to ripen.
Track Your Watermelon Growing
Add watermelon to your garden in the Planting Season app and get reminders for sowing, feeding, and ripeness checks.
Open the App →Frequently Asked Questions
When should I plant watermelon in Australia?
Watermelons need warm soil (above 22 degrees) to germinate. In most regions, plant from October to December. Tropical regions can plant from September to February. Sugar Baby and Yellow Baby mature fastest in shorter growing seasons.
How long do watermelons take to grow?
Small varieties like Sugar Baby take 10 to 12 weeks. Large varieties like Crimson Sweet and Charleston Grey take 14 to 16 weeks. The fruit needs consistent warmth throughout the growing period.
How do I know when a watermelon is ripe?
Check four things: the ground spot should be creamy yellow, the nearest tendril should be brown and dry, the melon should sound hollow when tapped, and the skin should lose its shine. Use all four tests together for the most reliable result.
How much space do watermelons need?
Watermelon vines spread 2 to 3 metres in each direction. Space mounds 2 to 3 metres apart. Small varieties like Sugar Baby need slightly less room. Vertical growing is possible but requires strong support for the heavy fruit.
See also: Watermelon in the Plant Library
