When to plant Rosemary in Subtropical Australia

Subtropical zone — applies to Brisbane, Gold Coast, Sunshine Coast, Coffs Harbour, Lismore and similar areas. Growing elsewhere? Temperate · Cool · Tropical · Arid.

Rosemary's seed window in the subtropics is short — sow in September or October, raising seedlings for transplant rather than sowing direct. Be realistic about the method: germination is slow and erratic at 14–28 days, and a seed-raised plant needs about 365 days to reach harvestable size, which is why most Brisbane gardeners start from a cutting or a nursery plant instead. However it arrives, give rosemary the sunniest, best-drained position in the garden and a generous 150 cm of space to grow into. It is hardy, and the mild winter is its favourite season here — summer humidity is the real threat.

Sowing calendar — subtropical zone

Green months are your sowing window: September to October.

Growing notes

Everything difficult about subtropical rosemary happens between December and February. This is a Mediterranean shrub adapted to dry heat, and weeks of storm rain on humid, heavy soil bring on root rot and sudden branch dieback — the classic pattern is a plant that sailed through winter turning grey and collapsing in late summer. Drainage is the whole defence: plant on a mound or in a raised bed, in lean sandy soil without added compost, and keep organic mulch well away from the stem. In pots, use a gritty mix and stand them where roof runoff cannot drown them.

Winter and the shoulder seasons repay the trouble. From autumn through spring rosemary grows densely, flowers, and needs almost nothing — established plants want no fertiliser and only occasional deep water, and the light frosts of the Lismore hinterland do not bother a hardy shrub like this. Trim lightly after flowering to keep it compact, but never cut back into bare wood, which rarely reshoots.

Treat rosemary here as reliable but not permanent. Even well-managed coastal plants can be lost to one exceptionally wet summer, so strike a few cuttings each autumn — they root far faster than the slow, year-long seed route — and there is always a replacement coming on.

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 sow rosemary in the subtropics?

Sow in September or October, raising seedlings for transplant. Germination takes 14–28 days and seed-raised plants need about a year to reach harvest size, so cuttings or nursery plants are the faster route.

Why did my rosemary suddenly die in summer?

Almost always wet-season root rot — weeks of storm rain on poorly drained soil kill the roots, and the bush greys off and collapses. Replant on a mound or in a raised bed with lean, fast-draining soil.

How long does rosemary take to grow from seed?

About a year to a harvestable plant, after a slow 14–28 day germination. Cuttings struck in autumn are much quicker.

Does rosemary grow well in Brisbane?

Yes, provided drainage is excellent. It thrives through the mild, dry winter; the humid December–February wet is the danger period, so mounded beds, pots and gritty soil are worth the effort.

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