When to plant Rosemary in Temperate Australia

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

September to November is the window for starting rosemary in temperate Australia — raise seedlings in pots or punnets, then transplant once they are well established. Be warned that this is a slow project: seed sown 3 mm deep takes 14–28 days to germinate, often erratically, and a plant needs around 365 days to reach maturity. What you get in return is a hardy, frost-proof perennial shrub that lives for many years. Plan for its adult size from the beginning — a mature bush wants around 150 cm of space — and choose a sunny, sharply drained position it can hold permanently.

Sowing calendar — temperate zone

Green months are your sowing window: September to November.

Growing notes

Rosemary's hardiness makes the temperate frost calendar almost irrelevant to an established plant — frosts from May to mid-October leave a mature bush untouched. Young seedlings are the vulnerable stage, which is exactly why the September-to-November sowing window works: seedlings raised in spring get a full growing season to toughen up before facing their first winter. Transplant them once they have a robust root system, not before.

Germination from seed is the trade for patience. Sow 3 mm deep, keep punnets warm and just moist, and expect a straggling emergence over 14–28 days with a strike rate that can be modest. Pot on the strongest seedlings and hold the rest in reserve. From sowing to a genuinely productive shrub is about a year, so treat the first season as an investment.

In the ground, rosemary wants what its Mediterranean origins suggest: full sun, lean soil and excellent drainage. Far more temperate-zone rosemary dies of wet feet than of cold — heavy, waterlogged winter soil rots the roots quietly and the plant browns off in spring. On clay, plant into a raised mound or grow in a large pot. Space at the full 150 cm; a cramped rosemary in humid airflow is a magnet for fungal trouble. Once established, water rarely and prune lightly after flowering to keep the bush dense.

Rosemary at a glance

Companion planting

Grows well with

Carrot: Volatile oils deter carrot fly

Broccoli: Deters cabbage white butterfly with volatile oils

Garlic: Both deter pests; garlic deters aphids, rosemary carrot fly

Common questions

When should I plant rosemary in temperate Australia?

Sow seed in punnets from September to November and transplant once seedlings are well rooted. Spring-raised plants get a full season of growth before their first winter.

How long does rosemary take to grow?

It is slow: seed takes 14–28 days to germinate and around 365 days to reach a mature, productive size. Many gardeners buy an established plant or strike cuttings to skip the wait.

Why did my rosemary suddenly die?

Poor drainage is the usual killer — waterlogged winter soil rots the roots, and the plant browns off later. Plant in full sun with sharp drainage, raise the bed on clay soils, and avoid overwatering.

Does rosemary survive frost?

Yes, established rosemary is hardy and handles temperate Australian frosts without protection. Only young seedlings need shelter through their first cold snaps.

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