When to plant Catnip in Subtropical Australia
Subtropical zone — applies to Brisbane, Gold Coast, Sunshine Coast, Coffs Harbour, Lismore and similar areas. Growing elsewhere? Temperate · Cool · Tropical · Arid.
Raise catnip seedlings for transplanting through autumn and winter, sowing from April to September while subtropical nights are cool and the air is drier. Seed germinates in 7-21 days, so sow it 5 mm deep in trays and transplant once seedlings are established, spacing plants a generous 60 cm apart in rows 60 cm apart. Catnip is frost hardy and quick, reaching usable size in 80-100 days, which makes a cool-season crop very achievable in Brisbane and Lismore gardens. Grown in a sunny, free-draining spot, it forms an aromatic grey-green clump that both cats and beneficial insects adore.
Sowing calendar — subtropical zone
Green months are your sowing window: April to September.
Growing notes
Catnip is a hardy mint-family herb, and in the subtropics its main enemy is not cold but humidity and its own vigour. The most common failure is powdery mildew and root rot in the wet season, when the plant's dense foliage traps moisture. Grow it as a cool-season crop, give it full sun and free-draining soil, and keep the generous 60 cm spacing so air moves through the clump. If mildew appears, cut the plant back hard; it reshoots cleanly.
The other issue is, predictably, cats. A single roll from a neighbourhood cat can flatten a young seedling, so protect new transplants with a low wire cage until they are woody enough to withstand attention. Seed sown directly is also worth caging while it germinates.
Catnip can spread and self-seed enthusiastically in mild subtropical conditions, so deadhead the flower spikes if you want to keep it contained, or let a few go to feed bees and hoverflies. Pinch the tips regularly to keep growth bushy and to harvest leaves for drying. Cut back in late winter to refresh the clump. In frost-free gardens it usually persists as a short-lived perennial rather than needing replanting each year.
Catnip at a glance
| Sowing depth | 5 mm |
|---|---|
| Plant spacing | 60 cm |
| Row spacing | 60 cm |
| Germination | 7-21 days |
| Days to maturity | 80-100 days |
| Frost tolerance | Hardy |
| Method | Plant Seedlings |
Common questions
- When should I sow catnip in the subtropics?
- Sow from April to September, through autumn and winter when nights are cool and the air is drier. This avoids the humid summer, when catnip is prone to mildew and rot, and gives the quick 80-100 day crop ideal growing conditions.
- How do I stop cats destroying my catnip seedlings?
- Protect young transplants with a low wire cage until they are woody enough to withstand rolling. Cats are drawn to bruised foliage, so an unprotected seedling can be flattened overnight, while an established plant shrugs off the attention.
- Why does my catnip get white powdery mildew?
- Powdery mildew thrives in subtropical humidity, especially on crowded plants with poor airflow. Space plants 60 cm apart, grow them in full sun, and cut affected plants back hard, as catnip reshoots cleanly from a hard prune.
- Does catnip come back each year in Brisbane?
- In frost-free Brisbane gardens catnip usually persists as a short-lived perennial and self-seeds readily. Cut it back in late winter to refresh the clump, and deadhead flowers if you want to stop it spreading through the bed.
Track catnip in your garden — sow dates, harvest countdowns, reminders. Free.
Add to my garden