When to Plant Sunflower in Canberra, Cold / Highland Guide

Sow September to December. Right now in September you can sow.

Published · Last reviewed · By Garden Buddy
Growing advice is reviewed by hand. Planting dates, current conditions and prices on this page update daily.

This Sunflower guide is written for the Cold / Highland zone, which takes in Canberra, Cooma and Bright. Somewhere else? Your postcode picks the right one.

Not your zone? Cairns Brisbane Sydney Melbourne Alice Springs Perth

Also handy: will it frost this week? and what grows in shade.

Sunflower

Photo: Wikimedia Commons

Sunflowers are dual-purpose annual plants grown for edible seeds and ornamental beauty. They are among the easiest and most rewarding plants for Australian gardens, growing rapidly from seed and producing spectacular flower heads that attract pollinators. Important note: sunflowers exhibit allelopathy. They release chemicals through roots and decomposing plant matter that inhibit the growth of certain nearby plants.

Planting Calendar for Cold / Highland

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
- - - - - - - - S S/T/D S/T/D T

S = Seed Tray   T = Transplant   D = Direct Sow

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Current Growing Conditions

Soil temperature: 11.2°C (optimal range: 15–35°C) ✗ Outside optimal range

Modelled from Open-Meteo forecast (Canberra), not a live sensor.

How to Grow Sunflower in Cold / Highland Australia

When to Plant

Sow November-January only. Short window. Choose fast-maturing dwarf varieties for reliable results.

Soil
Tolerates a wide range but prefers well-drained loam. Will grow in poor soil but produces larger heads in enriched soil. Remarkably drought-tolerant once established due to deep taproot.
pH Range
6.0-7.5
Sunlight
Full sun, minimum 6 hours, ideally 8+. Sunflowers are heliotropic (young heads follow the sun) and need maximum light for best growth.
Spacing
45cm apart, 75cm between rows
Watering
Water well at planting and during early growth. Once established (30cm+), sunflowers are surprisingly drought-tolerant. Deep weekly watering during head development and seed fill improves yield. Reduc

Companion plants: Corn, Squash/Pumpkin, Cucumber, Zinnia, Cosmos

Avoid planting near: Potato (allelopathic inhibition), Pole beans (allelopathic inhibition), Most brassicas, Grasses (allelopathically suppressed)

Cold / Highland Growing Tips for Sunflower

Recommended Varieties

  • Sunspot (dwarf, faster maturing)
  • Teddy Bear (dwarf)
  • Music Box (dwarf mix)
  • Giant Russian (if season long enough)

Key Challenges

  • Short growing season may not allow full seed maturation for tall varieties
  • Late and early frosts limit window
  • Cool nights slow growth

Pro Tips

  • Dwarf varieties (Sunspot, Teddy Bear) mature faster and are more reliable
  • Start in pots under cover in October for transplanting in November
  • Cloches or row covers extend season slightly

Harvesting Sunflower

When ready: For EDIBLE SEEDS: back of head turns from green to yellow-brown, petals have dried and fallen, seeds are plump and hard, head droops downward. For ORNAMENTAL cut flowers: harvest when first ring of outer florets opens, before fully open.

How to harvest: For seeds: cut head with 30cm of stem. Hang upside down in dry, airy place inside a paper bag or with cloth underneath to catch falling seeds. Alternatively, rub seeds out of head by hand once dry (wear gloves, rough). For cut flowers: cut stems early morning, place in water immediately.

Common Sunflower Pests in Cold / Highland Zones

Aphids and Leaf Spots, risk: MODERATE (score: 45/100)

Organic prevention: Early planting so heads develop before peak moth activity (mid-late summer). Destroy infected heads after harvest. Clean up all crop residue.

View all pest alerts →

Where to next

Also worth sowing in the cold and highland zone this September: Sweet Corn, Beetroot, Chilli Peppers and Snow Peas.

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Common Questions About Sunflower

When do you plant sunflower in Australia?

It depends on your climate zone, not the calendar month alone. Planting months by zone:

Does sunflower grow all year round in Canberra?

No. In the Cold / Highland zone the planting months are Sep to Dec. Outside that window it either bolts, sulks or gets cut down by the weather.

Which zone am I in?

Type your postcode into the box under the heading and the page tells you, and links this crop in your own zone if it differs. Or look it up on the grow zone map. This page is the Cold / Highland zone, Canberra is its reference city.