When to plant Watermelon in Temperate Australia

Temperate zone — applies to Sydney, Melbourne, Adelaide, Perth, Newcastle and similar areas. Growing elsewhere? Cool · Subtropical · Tropical · Arid.

Watermelon sowing in temperate Australia runs from August to December, with seed going direct into the ground 15–20 mm deep — but the calendar carries a caveat, because watermelon is frost tender and the last temperate frost typically lands mid-October. Early sowings need a genuinely warm, protected spot or a cover; from late October onwards, sow with confidence into warmed soil. Germination takes 6–18 days depending on soil temperature, and fruit is ready in 70–120 days depending on variety. Give the vines serious room — 60–80 cm between plants and 150–180 cm between rows — because they'll take it whether offered or not.

Sowing calendar — temperate zone

Green months are your sowing window: August to December.

Growing notes

Cold soil is watermelon's undoing in a temperate climate. Seed sown into chilly, damp ground rots before it germinates — the single most common failure — so treat the August and September end of the window as advanced play, viable only with cloches, a hot sheltered microclimate or pre-warmed beds. For most gardens, late October and November are prime; even a December sowing of a faster 70–90 day variety ripens comfortably before the first autumn frost arrives around May.

Pick the hottest spot you have. Full sun all day, wind protection, and soil mounded into low hills improve both warmth and drainage — work plenty of compost into each mound before sowing two or three seeds and thinning to the strongest.

Water deeply and regularly while vines are running and fruit is swelling, ideally at the base to keep foliage dry, then ease the water right off in the final couple of weeks — slightly drier finishing concentrates the sugars.

Knowing when to pick takes practice, since melons don't ripen further off the vine:

• The tendril nearest the fruit dries out and turns brown
• The patch where the melon rests on the ground turns from white to buttery yellow
• A ripe fruit sounds hollow when thumped
• The skin dulls, losing its glossy sheen

Watermelon at a glance

Common questions

When can I plant watermelon in Australia?

The temperate sowing window runs August to December, but hold off until after the last frost in mid-October unless you can protect seedlings. Late October and November sowings into warm soil are the most reliable.

How long does watermelon take to grow?

Seed germinates in 6–18 days depending on soil warmth, and fruit takes 70–120 days to ripen depending on the variety. Faster varieties suit later sowings.

Why didn't my watermelon seeds germinate?

Cold, wet soil is the usual reason — the seed rots before it can sprout. Wait until the soil has genuinely warmed, sow 15–20 mm deep into mounds, and germination is far more reliable.

How do I know when a watermelon is ripe?

Check that the tendril nearest the fruit has dried brown, the ground spot has turned yellow, and the melon sounds hollow when thumped. They don't ripen further after picking, so don't rush it.

Can you grow watermelon in Melbourne?

Yes — Melbourne sits in the temperate zone, so sow direct from late October to December once soil is warm, and choose a faster-maturing variety at the 70–90 day end to ripen fruit before autumn.

Keep exploring