How to grow Basil in Australia
Basil is the classic summer herb: fast, fragrant and happiest in heat. It needs plenty of sun, rich soil and regular water, and it is killed by frost and sulks in cold, damp weather. Pinch it often and remove the flowers, and one plant will keep giving leaves for months.
📖 Our full guide: How to Grow Basil in Australia
At a glance
When to sow by region
| Region | When to sow | Regional note |
|---|---|---|
| South East Queensland | August to March | |
| Northern Rivers NSW | September to March | Very frost sensitive. Start later inland. |
| Sydney & Coastal NSW | September to March | Start indoors September; transplant outdoors October onward after frost risk passes and soil warms to 18°C+. |
| Melbourne & Victoria | October to December | Sow outdoors from October to December once nights stay above 10°C, usually from mid October. Cold soil and frost kill basil instantly, so do not sow in August or September. |
| Adelaide & SA | September to January | Sow Sep undercover or Oct to Dec direct after frost. A Jan sowing crops into autumn. Plants die at the first cold snap in May. |
| Perth & WA | August to December | Seed indoors August, plant out late September. Succession sow in bright shade Oct to Dec; a mid Dec sowing carries pesto into February. |
| Tasmania | November and December | Narrow window. Sow Nov to Dec in the warmest spot or a greenhouse. Cold nights below 10C stop it dead. Pot up before autumn. |
| Canberra & ACT | November and December | Frost kills basil. Sow Nov to Dec after the last frost in early November. The short warm window limits the season. |
| North Queensland | April to November | Plant Apr to Nov. Townsville nurseries start basil in April. Downy mildew hits hard in the monsoon months Dec to Mar, so rest the bed then. |
| Darwin & Top End | All year | Year round in Darwin. Thrives in heat and humidity. |
Where to plant
Grow basil in full sun in rich, well-drained soil with compost dug in, in the garden or a pot. It dislikes cold, damp conditions, so do not plant it out until nights are warm. Space plants well apart so air moves between them, which helps keep downy mildew away.
In the south basil is a spring to autumn plant that dies at the first cold snap. In the north it grows for much of the year.
- Melbourne, Canberra and Hobart: sow or plant from October or November to December, once nights stay above about 10°C. The season is short, so start with seedlings and grow it in the warmest spot.
- Sydney and Adelaide: start seed under cover in September and plant out from October; a January sowing crops into autumn.
- Perth: sow indoors in August and plant out from late September, with successive sowings to December.
- South East Queensland and the Northern Rivers: sow from late winter right through summer and into autumn.
- North Queensland: plant from April to November. Rest the bed in the monsoon months, when downy mildew hits hard. Darwin: grows year round.
Choosing a variety
- Sweet Genovese is the Italian basil for pesto and tomatoes.
- Thai basil (horapa) has an aniseed flavour and stands heat and humidity well.
- Greek basil forms a small, bushy plant with tiny leaves.
- Lemon basil and purple types such as Dark Opal add different flavours and colour.
How to plant
- Sow seed in punnets in warmth, very shallowly, about 3 mm deep or just pressed into the surface.
- Keep the mix just moist and warm; seedlings appear in one to two weeks.
- Plant out about 4 to 6 weeks later, once nights are warm, about 25 cm apart.
- Or skip the seed and buy a punnet of seedlings, which is easier in cool climates.
- Water in and mulch lightly.
Watering and feeding
Keep the soil evenly moist; basil wilts quickly in hot weather, especially in pots. Water at the base in the morning rather than in the evening and avoid wetting the leaves, as wet leaves overnight encourage disease.
Feed lightly every few weeks with a liquid fertiliser for steady leafy growth.
Pruning and care through the year
- Pinch out the growing tips regularly, just above a pair of leaves, to make the plant bushy.
- Pinch off flower buds as soon as they appear. Flowering reduces the flavour and the plant stops making new leaves.
- In cool climates, a sunny windowsill or a cover on cold nights can keep a potted plant going longer into autumn.
Harvesting
Start picking once plants are about 10 to 20 cm tall. Take a few shoot tips from each plant at a time, cutting above a pair of leaves, rather than stripping single leaves; the more you pick, the bushier it grows. When you need a lot, cut whole stems or pull a plant.
Basil blackens in the fridge. Keep picked stems in a glass of water on the bench, or make pesto and freeze it.
Growing in pots
Basil grows well in a pot at least 20 to 25 cm wide, which also lets you move it into the sun or under cover on cold nights. Use a quality potting mix, water often in hot weather, and feed every couple of weeks.
Companion planting
Basil is a natural partner for summer fruiting crops, which want the same sun, soil and water. Its flowers, if you let a plant bloom, bring in bees.
Good companions
- Tomato Likes the same sun and watering and fits between plants.
- Capsicum Another warm-season crop with the same needs.
- Oregano A sun-loving herb that grows happily alongside it.
Keep apart
Avoid planting these close to basil.
- Sage Prefers drier, leaner soil than basil, so they are hard to water together.
- Rue A strong-smelling herb traditionally kept away from basil.
Pests and diseases
Downy mildew is now the most serious basil problem in humid areas. Snails and caterpillars are the usual pests.
Pests to watch for
- Snails Holes chewed in leaves overnight and slime trails. Slugs do the same.
- Caterpillars Chewed leaves with droppings on the plant.
- Whitefly Tiny white insects that fly up from the undersides of leaves.
- Aphids Clusters of small insects on the shoot tips.
Diseases to watch for
- Downy mildew Blotchy yellowing on the upper leaf and grey to black fuzz underneath, spreading fast in humid weather. Remove affected plants, space plants widely and water in the morning.
- Fusarium wilt Plants wilt and stems brown even when the soil is moist. Remove them and plant basil elsewhere next time.
Common questions
Why is my basil going black or yellow?
Blotchy yellow leaves with grey or black fuzz underneath are a sign of basil downy mildew, which was first found in Queensland in 2017 and spreads in humid weather. Leaves that blacken after a cold night have been chilled. Basil also blackens in the fridge.
Should I remove basil flowers?
Yes, if you want leaves. Flowering reduces the flavour and stops the plant making new leaves. Pinch off flower buds as they appear.
How do I pick basil so it keeps growing?
Pick shoot tips just above a pair of leaves rather than single leaves from the bottom. Two new shoots grow from each cut, so the plant gets bushier the more you pick.
When should I plant basil?
Once nights are warm and frost has passed. In the south that is from October or November. In South East Queensland basil grows from late winter to autumn, and in the tropics it grows for much of the year. Pick your region at the top of the page for the months.
Is basil an annual or a perennial?
Sweet basil is an annual in most of Australia and dies with the first cold. Some types, such as Greek basil, are longer lived in warm areas.
How often should I water basil?
Keep the soil evenly moist. In summer that may mean every day for a pot and every two or three days in the garden. Water at the base in the morning so the leaves are dry by night.
Can I grow basil indoors over winter?
In cool climates you can keep a potted plant going on a sunny windowsill, but growth slows in short winter days. Many gardeners simply sow fresh basil each spring.
Sources we checked: Gardening Australia: Basil plant finder; ABC News: How to grow basil and keep it alive in colder climates; Queensland DAF: Basil downy mildew; RHS: How to grow basil.