How to grow Cosmos in Australia
Sow cosmos in full sun in light, free-draining soil that is not too rich, since fertile ground produces leaves at the expense of flowers. Water while young, then they handle dry conditions well.
At a glance
- Difficulty: Beginner
- Sun: Full sun
- Water: 3 litres a week, watered every 3 days
- Spacing: 30 cm
- Time to harvest: 60 days
- Time to germinate: 7 days
- Soil pH: 6 to 7
- Frost tolerance: Frost tender
When to sow by region
| Region | When to sow | Regional note |
|---|---|---|
| South East Queensland | September to February | |
| Northern Rivers NSW | September to February | |
| Sydney & Coastal NSW | September to February | |
| Melbourne & Victoria | October to December | Frost tender. Sow Oct to Dec after frost in lean soil. Self seeds, and seedlings appear once frosts finish. |
| Adelaide & SA | September to December | Sow Sep to Dec direct. Flowers through summer on little water; rich soil gives leaf and few flowers. |
| Perth & WA | September to December | Sow Sep to Dec direct. Flowers through summer on little water; rich soil gives leaf and few flowers. |
| Tasmania | October to December | Sow Oct to Dec after frost. Flowers until the first autumn frost. |
| Canberra & ACT | November and December | Frost tender. Sow Nov to Dec after the last frost in early November. Self seeds; seedlings emerge once frosts finish. |
| North Queensland | April to October | Dry season Apr to Oct. Wet season storms flatten the tall stems and the plants rot. |
| Darwin & Top End | April to October | Dry season Apr to Oct. Wet season storms flatten the tall stems and the plants rot. |
Varieties
- Sensation Mix
- Cosmic Orange (Sulphureus)
- Double Click Mix
Companion planting
Good companions
Harvest and storage
Harvest tip
Cut stems when buds are showing colour and barely open for the longest vase life. Frequent cutting and deadheading keeps the plant blooming prolifically.
Storage
Cut flowers last 5 to 7 days in a vase. Harvest when buds just open. Save seed from dried heads.