When & How to Plant Dahlias in Australia for a Summer Bloom

Dahlias are the showstoppers of the summer garden, and the Pompon variety — with its perfectly round, densely petalled blooms — is one of the most beloved. Growing dahlias from seed is easy when you time it right for the Australian climate.

When to Plant Dahlia Seeds in Australia

Dahlias are frost-sensitive, so timing is everything. Spring is your window.

• VIC, TAS, SA, ACT: Start seeds indoors in September, transplant after the last frost (October–November).
• NSW, QLD, WA: Sow directly outdoors from October once soil has warmed to at least 18°C.
• NT & tropical QLD: Dahlias can be grown in the dry season (April–August) to avoid the wet season humidity.

How to Sow Dahlia Seeds

1. Sow seeds 6mm deep in seed-raising mix.
2. Keep moist and warm (20–25°C) — germination takes 7–14 days.
3. Transplant seedlings outdoors once they have 2–3 sets of true leaves and all frost risk has passed.
4. Space plants 30–45cm apart in garden beds.

Soil, Sun & Staking

Dahlias need full sun (6+ hours), rich well-drained soil, and regular feeding with a low-nitrogen, high-potassium fertiliser once buds appear. Taller varieties benefit from staking — insert a stake at planting time to avoid disturbing roots later.

Pinching for More Blooms

Pinch out the growing tip when plants reach 30cm tall. This encourages bushy growth and more flowers — a simple trick that doubles your display.

Deadhead regularly to keep plants blooming right through summer and into autumn.

Plant your dahlia seeds this October with our Dahlia Pompon Mix Seeds – Dahlia x cultorum and enjoy a summer garden full of colour.