When to Plant Basil in Cairns, Tropical Guide

Sow year round in Cairns. That includes right now, in September.

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

This Basil guide is written for the Tropical zone, which takes in Cairns, Townsville and Darwin. Somewhere else? Your postcode picks the right one.

Not your zone? Brisbane Sydney Melbourne Canberra Alice Springs Perth

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

Basil

Photo: Wikimedia Commons

The king of summer herbs. Sweet basil (O. basilicum) is the standard culinary variety, but Thai basil (O. basilicum var. thyrsiflora), lemon basil (O. x citriodorum), and purple basil (O. basilicum 'Purpurascens') each bring distinct flavours. Extremely frost-sensitive. Even a light frost kills it dead. Thrives in warm conditions across most of Australia from spring through autumn.

Planting Calendar for Tropical

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

S = Seed Tray   T = Transplant   D = Direct Sow

You can sow basil in any month in Tropical, but the months are not equal. Summer heat brings faster bolting and heavier pest pressure, so pick a heat tolerant variety, sow little and often, and give afternoon shade from December through February.

Want a nudge when it is Basil sowing time in Cairns?

One email a week with what is worth planting in the Tropical zone right now, Basil 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: 21.4°C (optimal range: 18–35°C) ✓ Ready to plant

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

How to Grow Basil in Tropical Australia

When to Plant

Year-round in frost-free areas, but dry season (Apr-Sep) is easiest. Wet season brings extreme fungal pressure. Seed trays year-round, transplant year-round.

Soil
Rich, well-drained soil with plenty of compost. Warm soil is critical.
pH Range
6.0-7.0
Sunlight
Full sun (minimum 6 hours). More sun = more essential oils = more flavour.
Spacing
25cm apart, 40cm between rows
Watering
Regular, consistent watering. Basil wilts dramatically when dry but recovers quickly. Water at base, not overhead, to reduce fungal issues. Morning watering preferred.

Companion plants: Tomato, Capsicum, Chilli, Marigold

Avoid planting near: Rue, Sage, Common Thyme

Tropical Growing Tips for Basil

Recommended Varieties

  • Thai basil (heat tolerant, slower to bolt)
  • Holy basil (Tulsi)
  • Lemon basil
  • African Blue basil (perennial in tropics)

Key Challenges

  • Basil downy mildew in wet season
  • Bolting in extreme heat above 35C
  • Fungal diseases from humidity

Pro Tips

  • Thai basil outperforms sweet basil in tropical heat
  • Grow under partial shade in summer to reduce bolting
  • Succession sow every 3 weeks as plants bolt quickly

Harvesting Basil

When ready: Begin harvesting when plants have 6+ sets of leaves. Harvest before or at first sign of flower buds for best flavour.

How to harvest: Pinch or cut stems just above a leaf pair. This encourages two new shoots from that node. Never strip more than 1/3 of plant at once. Harvest in morning after dew dries when essential oil concentration peaks.

Common Basil Pests in Tropical Zones

Aphids and Fungal Issues, risk: LOW (score: 30/100)

Organic prevention: Avoid excess nitrogen. Companion plant with marigolds. Check plants regularly.

View all pest alerts →

Where to next

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

Also worth sowing in the tropical zone this September: Lemongrass, Ginger, Cucumber and Okra.

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Common Questions About Basil

When do you plant basil in Australia?

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

Does basil grow all year round in Cairns?

Yes, every month is on the calendar for the Tropical zone, though not every month is equally easy.

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 Tropical zone, Cairns is its reference city.