When to Plant Watermelon in Perth, Mediterranean Guide

Sow August to December. Right now in October you can sow.

Planting window
Plant once the soil is warm, from late September in Perth and October in Adelaide. The long hot summers suit melons well.
Days to harvest
about 12 weeks
Sunlight
Full sun (minimum 8 hours). More heat and sun = sweeter fruit.
Water needs
Deep regular watering during vine growth and fruit development. CRITICAL: reduce watering...
Spacing
150cm apart, 250cm between rows
Soil pH
6.0-7.0
Shop price
$3.49/kg average

Published · Last reviewed · By GardenBuddy.au
Growing advice is reviewed by hand. Planting dates, current conditions and prices on this page update daily.

This Watermelon guide is written for the Mediterranean zone, which takes in Perth, Adelaide and Bunbury. Somewhere else? Your postcode picks the right one.

Not your zone? Cairns Brisbane Sydney Melbourne Canberra Alice Springs

Also handy: will it frost this week? and what grows in shade.

Watermelon

Photo: Wikimedia Commons

Watermelon is a warm-season vine crop native to Africa, requiring long hot summers and ample space. Australia's arid interior and northern regions produce some of the sweetest watermelons in the world. Home-grown watermelon in warm zones is deeply rewarding. Requires substantial space (each vine can spread 3-4m), consistent warmth, and patience (80-100+ days to maturity).

See what grows now in your own postcode

Planting Calendar for Mediterranean

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
- - - - - - - S S/T/D S/T/D T/D T/D

S = Seed Tray   T = Transplant   D = Direct Sow

Want a nudge when it is Watermelon sowing time in Perth?

One email a week with what is worth planting in the Mediterranean zone right now, Watermelon included, plus which veg has jumped in price at the supermarket. Free, and you can stop it in one click.

Current Growing Conditions

Soil temperature: 15.6°C (optimal range: 21–35°C) ✗ Outside optimal range

Modelled from Open-Meteo forecast (Perth), not a live sensor.

What this month normally looks like

In October the Mediterranean zone normally runs 22°C by day and 10°C overnight, with about 38 mm of rain over 6 or 7 wet days. The coldest October night on record across the zone was -0.2°C, so a late frost is not out of the question. Averages 1991 to 2026, 19 postcodes, SILO.

How to Grow Watermelon in Mediterranean Australia

When to Plant

Plant once the soil is warm, from late September in Perth and October in Adelaide. The long hot summers suit melons well.

Soil
Sandy loam to loam, well-drained, enriched with compost. Sandy soils warm fastest. Watermelons tolerate slightly sandier conditions than most cucurbits.
pH Range
6.0-7.0
Sunlight
Full sun (minimum 8 hours). More heat and sun = sweeter fruit.
Spacing
150cm apart, 250cm between rows
Watering
Deep regular watering during vine growth and fruit development. CRITICAL: reduce watering 2 weeks before harvest to concentrate sugars. Excess water at maturity dilutes sweetness and causes splitting.

Companion plants: Corn, Sunflower, Nasturtium, Radish (trap crop for flea beetles)

Avoid planting near: Potato, Other Citrullus if seed saving

Grow before, grow after

Watermelon belongs with the cucurbits, the fruiting crops turn of a four turn bed rotation.

Grow before it
Leafy greens and brassicas (Lettuce, Silverbeet, Broccoli)
Grow after it
Roots and alliums (Carrot, Beetroot, Onion)

Give the bed 3 turns before cucurbits go back in. Pumpkin, cucumber and zucchini want a bed with fresh compost dug through.

Mediterranean Growing Tips for Watermelon

Recommended Varieties

  • Crimson Sweet
  • Sugar Baby
  • Moon and Stars
  • Jubilee

Key Challenges

  • Dry summer needs irrigation
  • Cool spring start

Pro Tips

  • Good watermelon zone with warm dry summers
  • Drip irrigate, reduce at maturity
  • Black plastic mulch for earlier planting

Harvesting Watermelon

When ready: Multiple indicators needed: 1) Tendril nearest fruit turns brown and dry, 2) Ground spot (where fruit sits) turns from white to creamy yellow, 3) Skin resists thumbnail scratch (hard rind), 4) Dull thud when tapped (not hollow ring). Use ALL indicators together. No single one is reliable alone.

How to harvest: Cut stem cleanly with sharp knife. Do not pull or twist. Handle carefully.

Worth growing?

A 2.4 m × 1.2 m bed fits 1 plant, about $14 worth at today’s Aldi prices, checked today.

That is roughly 4 kg at $3.49 a kilo.

Draw your watermelon bed → No account needed.

Common Watermelon Pests in Mediterranean Zones

Fungal Infections, risk: LOW (score: 36/100)

In the pest library for watermelon:

Two-spotted Spider Mite, high severity Root-knot Nematode, high severity Powdery Mildew, high severity Downy Mildew, high severity Fusarium Wilt, high severity Mosaic Viruses (CMV, ToMV, ZYMV), high severity Pumpkin Beetle, moderate severity

View all pest alerts →

Where to next

What watermelon costs in the shops right now, retailer by retailer, updated daily.

Also worth sowing in the mediterranean zone this October: Lemongrass, Dwarf Beans (Bush), Eggplant (Aubergine) and Parsnip.

The pest most likely to find your watermelon: Fusarium Wilt.

Supermarket Price

Current average retail: $3.49/kg (12-month range: $3.49–$3.99)

Grow your own and save on grocery bills.

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Common Questions About Watermelon

When do you plant watermelon in Australia?

It depends on your climate zone, not the calendar month alone. Planting months by zone:

Does watermelon grow all year round in Perth?

No. In the Mediterranean zone the planting months are Aug to Dec. Outside that window it either bolts, sulks or gets cut down by the weather.

Which zone am I in?

Type your postcode into the box under the heading and the page tells you, and links this crop in your own zone if it differs. Or look it up on the grow zone map. This page is the Mediterranean zone, Perth is its reference city.