How to grow Sunflower in Australia
Sunflowers (Helianthus annuus) are fast, cheerful summer annuals, from 40 cm dwarf types for pots to giants taller than a person. They are easy to grow from seed sown directly in warm soil, they feed bees and birds, and the big heads give edible seed at the end of the season.
📖 Our full guide: Growing Sunflowers From Seed in Australia: When to Plant
At a glance
When to sow by region
| Region | When to sow | Regional note |
|---|---|---|
| South East Queensland | September to March | |
| Northern Rivers NSW | September to March | |
| Sydney & Coastal NSW | September to February | Sow direct Sep to Feb once the soil warms. Frost tender. |
| Melbourne & Victoria | October to December | Frost-tender; sow Oct to Dec only (soil 15°C+). Dies in frost. Narrow window. |
| Adelaide & SA | September to December | Sow Sep to Dec direct. Sunflowers take the heat with deep watering; stake tall types against the wind. |
| Perth & WA | September to December | Sow Sep to Dec direct. Sunflowers take the heat with deep watering; stake tall types against the wind. |
| Tasmania | October to December | Sow Oct to Dec. Choose early varieties for the short summer. |
| Canberra & ACT | November and December | Sow direct Nov to Dec after the last frost in early November. Sowings after December rarely flower before autumn frost. |
| North Queensland | April to September | Sow Apr to Sep in the dry season. Wet season humidity brings fungal disease and storms flatten the tall stems, so have heads finished before the rain returns. |
| Darwin & Top End | April to August | Dry season Apr to Aug. Wet season storms flatten and rot stems. |
Not to be confused with: Sunflower Microgreens, which are seedlings of the same plant cut about ten days after sowing.
Where to plant
Sunflowers need full sun, at least six hours a day, and well-drained soil. They are not fussy about fertility, but moderate feeding gives bigger heads. Tall types are top heavy, so choose a spot sheltered from strong wind or be ready to stake them.
They are frost tender and need warm soil to germinate. Plant tall types on the south side of the garden so they do not shade other crops.
- South East Queensland and the Northern Rivers: sow from September to March.
- Sydney: sow from September to February once the soil warms.
- Adelaide and Perth: sow from September to December. Water deeply in heat and stake tall types against the wind.
- Melbourne and Hobart: sow from October to December. Choose quicker, earlier varieties in Hobart's short summer.
- Canberra: sow in November and December after the last frost. Later sowings rarely flower before autumn frost.
- North Queensland: sow from April to September in the dry season; Darwin from April to August. Wet season storms flatten the tall stems and humidity brings fungal disease.
Choosing a variety
- Giant single-stem types grow 2 to 3 m tall with one huge head, best for seed and for children's gardens.
- Medium branching types, around 1.5 m, give many smaller flowers over a longer period and are good for cutting.
- Dwarf types, around 40 cm, flower sooner, in about 8 to 10 weeks, and suit pots and windy spots.
How to plant
- Sow seed directly where the plants will grow, as sunflowers dislike root disturbance.
- Sow about 1 to 2 cm deep once the soil is warm and frost has passed.
- Space dwarf types about 30 cm apart and tall types 50 to 60 cm apart, or sow two seeds per spot and keep the stronger.
- Water in and keep the soil just moist until seedlings appear. Protect seedlings from snails and birds.
Watering and feeding
Water deeply but less often, at the base of the plant. Deep watering encourages deep roots that help tall plants stand up. Water more often in hot weather and once buds form.
Feed moderately, about every six weeks with a flower-promoting fertiliser once established. Too much nitrogen gives tall, leafy plants with smaller flowers.
Pruning and care through the year
- Stake tall varieties with a strong bamboo or timber stake, tied loosely with soft twine, before they get top heavy.
- On branching types, cut spent flowers to keep new ones coming.
- Cover seed heads with netting or a paper bag once the petals fall if you want the seed, as birds will strip them.
Cutting flowers and harvesting seed
For a vase, cut flowers early in the morning when they are just opening, and stand them in water straight away.
For seed, leave the head on the plant until the back of the head turns yellow to brown and the seeds are plump. Cut the head with a length of stem and hang it upside down in a dry, airy spot until the seeds loosen. Knock the head against a bucket and prise out the rest with your thumbs. Dry the seed fully before storing it in an airtight container in a cool, dry place.
Growing in pots
Dwarf sunflowers grow well in pots. A 30 cm pot fits about three dwarf plants. Use a quality potting mix, a sunny spot, and water regularly, as pots dry out fast in summer. Tall types are not suited to pots.
Using it
Roast the seeds or eat them raw once shelled, or leave whole heads out for birds in autumn. The flowers last about a week in a vase.
Saving seed
Save seed from your best open-pollinated plants (not hybrids), dry it well and store it in a labelled paper bag in a cool, dry place to sow next spring.
Companion planting
Sunflowers are tall, so use them as a sunny backdrop or a living trellis, and plant them where their shade will not fall on sun lovers.
Good companions
- Cucumber Can climb sturdy sunflower stalks and enjoys a little light shade in hot weather.
- Corn Another tall summer crop for the back of the bed with the same warm season.
- Tomato Sunflowers bring in bees and other beneficial insects to a summer bed.
Keep apart
Avoid planting these close to sunflower.
- Potato Often listed as a poor neighbour for sunflowers. Give each its own bed.
Pests and diseases
Sunflowers are easy, but snails on seedlings and birds on the ripening seed are the main problems.
Pests to watch for
- Snails Seedlings chewed off just after they come up.
- Birds Seed stripped from the ripening heads.
- Aphids Clusters on the stems and under leaves, often with ants.
- Caterpillars Chewed leaves and holes in the flower heads.
Diseases to watch for
- Powdery mildew White powder on the lower leaves late in the season.
- Downy mildew Pale, yellow patches on the leaves with white growth underneath in humid weather.
- Botrytis Grey, fuzzy mould rotting the back of the flower head in wet weather.
- Rust Small orange-brown pustules on the leaves.
Common questions
When should I plant sunflowers in Australia?
In spring and summer once the soil is warm: September to March in South East Queensland, September to February in Sydney, and October to December in Melbourne and Hobart. In the tropics, sow in the dry season. Pick your region at the top of the page for the months.
How long do sunflowers take to grow?
Dwarf types flower in about 8 to 10 weeks and tall types in about 12 weeks, sometimes longer for giants.
Can I grow sunflowers in pots?
Yes, dwarf types. A 30 cm pot holds about three plants. Tall types need the ground.
How do I harvest sunflower seeds?
Wait until the back of the head turns yellow to brown. Cover it against birds, then cut it and hang it upside down somewhere dry and airy. Knock the seeds out over a bucket and dry them fully before storing them airtight.
Why are my sunflowers falling over?
Tall types are top heavy, and wind or wet soil topples them. Stake them early, water deeply rather than often to grow deep roots, and plant them out of strong wind.
Should I transplant sunflower seedlings?
It is best to sow them directly, as they dislike root disturbance. If you raise them in pots, plant them out young, before the roots fill the pot.
Sources we checked: Yates: How to grow sunflowers; Gardening Australia: Harvesting sunflower seed.