When to Plant Basil in Cairns, Tropical Guide
Soil temperature is modelled from Open-Meteo forecast (Cairns), not a live sensor.
What this month normally looks like in Tropical
In October the Tropical zone normally runs 34°C by day and 23°C overnight, with about 53 mm of rain over 5 or 6 wet days. Averages 1991 to 2026, 37 postcodes, SILO.
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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.
- Planting window
- All year
- Days to harvest
- 60 days
- Sun
- Full sun
- Water
- Regular
- Spacing
- 25 cm apart
- Soil pH
- 6.0–7.0
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.
Published · By GardenBuddy.au
Planting dates, current conditions and prices on this page update daily.
Photo: Wikimedia Commons
Planting Calendar for Tropical
- Jan S/T
- Feb S/T
- Mar S/T
- Apr S/T
- May S/T
- Jun S/T
- Jul S/T
- Aug S/T
- Sep S/T
- Oct S/T
- Nov S/T
- Dec 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.
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How to Grow Basil in Tropical Australia
- Soil
- Rich, well-drained soil with plenty of compost. Warm soil is critical.
- Salt
- Moderately sensitive. Copes with a little salt, but the harvest drops on salty bore water.
- 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.
- Good companions
- Tomato, Marigold, Capsicum, Lemongrass, Potato
- Keep away from
- Rosemary (different water needs), Rue, Sage, Thyme (different water needs)
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
Pests and problems for Basil in Tropical
- Aphids and Fungal Issues Moderate
- Fusarium Wilt Use disease-free seed. Rotate planting locations. Grow in containers with fresh potting mix each season. Watch
- Common Garden Snail Watch
- Slugs Watch
- Basil Downy Mildew Space plants for maximum airflow. Water at base only, never overhead. Morning watering so foliage dries quickly. Choose resistant varieties... Watch
- Fungal diseases Fungal diseases from humidity Watch
Organic prevention (Aphids): Avoid excess nitrogen. Companion plant with marigolds. Check plants regularly.
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.
Storing and preserving basil
How to keep it
- Pesto (freezing). Blend 2 cups basil, 1/2 cup olive oil, 1/3 cup pine nuts or macadamias, 2 cloves garlic, 1/2 cup parmesan. Freeze in ice cube trays, then transfer to bags. Omit cheese for longer storage. Add fresh when thawing. Keeps: 6-12 months frozen.
- Freezing in oil. Chop leaves finely, pack into ice cube trays, cover with olive oil. Freeze. Pop cubes into labelled bags. Drop directly into hot pans for cooking. Keeps: 6 months frozen.
- Drying. Hang small bunches upside down in dark, dry, well-ventilated area for 1-2 weeks. Or dehydrate at 35C for 4-6 hours. Note: dried basil loses significant flavour compared to fresh or frozen. Keeps: 12 months in airtight jar.
- Basil-infused vinegar. Pack clean basil leaves into sterilised bottle. Cover with warm white wine vinegar. Seal and store in dark place for 2-4 weeks. Strain and rebottle. Keeps: 12 months.
- Herb butter. Blend 250g softened butter with 1 cup finely chopped basil, pinch of salt. Roll in cling wrap into log shape. Refrigerate or freeze. Slice rounds as needed. Keeps: 2 weeks refrigerated, 3 months frozen.
What basil costs in the shops right now, retailer by retailer, updated daily.
What members get
- Soil and weather from your nearest station
- An email when it's time to sow
- Your own garden plan, including planning from a photo
- Price history and price alerts
- Pest risk alerts for your area
- Full salt and canning detail
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:
- Tropical (Cairns): all year
- Subtropical (Brisbane): Jan to Mar, Aug to Dec
- Warm Temperate (Sydney): Jan to Feb, Sep to Dec
- Cool Temperate (Melbourne): Jan, Sep to Dec
- Cold / Highland (Canberra): Jan, Oct to Dec
- Arid / Semi-Arid (Alice Springs): Jan to Feb, Aug to Dec
- Mediterranean (Perth): Jan to Feb, Aug to Dec
Can you grow basil all year round in Cairns?
Yes, every month is on the calendar for the Tropical zone, though not every month is equally easy. 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.
When should I plant Basil in Cairns?
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.
What soil temperature do Basil need?
Basil germinate best when soil temperature is between 18°C and 35°C.
How do I know when Basil are ready to harvest?
Begin harvesting when plants have 6+ sets of leaves. Harvest before or at first sign of flower buds for best flavour.
What are the best Basil varieties for Cairns?
Recommended varieties for the Tropical zone include: Thai basil (heat tolerant, slower to bolt), Holy basil (Tulsi), Lemon basil, African Blue basil (perennial in tropics).
What grows well with Basil?
Good companion plants for Basil include: Tomato, Marigold, Capsicum, Lemongrass, Potato.
Are basil salt tolerant?
Only a little. Basil are moderately sensitive to salt, so the harvest drops on salty bore water. Mix salty water with rainwater, and mulch the bed.
Which zone am I in?
Type your postcode into the box near the top of the page and it 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.