When to plant Impatiens in Temperate Australia

Temperate zone — applies to Sydney, Melbourne, Adelaide, Perth, Newcastle and similar areas. Growing elsewhere? Cool · Subtropical · Tropical · Arid.

Raise impatiens as seedlings and transplant once the weather warms, sowing across the shoulder months from February to May and again from August to October. Because it is frost tender, hold plants under cover until frost danger has passed before setting them out. Seed germinates in 14–21 days and needs warmth and light, so barely cover it at 5 mm. Space transplants 30–40 cm apart with 20–30 cm between rows, and expect flowering in around 80–100 days. In temperate gardens around Sydney and Melbourne, impatiens shines in the shady, moist beds where most bedding flowers struggle.

Sowing calendar — temperate zone

Green months are your sowing window: February to May and August to October.

Growing notes

Impatiens earns its keep by flowering generously in shade, which makes it invaluable for the difficult spots under trees or along a south-facing wall. In a temperate climate the key constraints are frost at one end of the season and dryness at the other.

Start seed in warmth and do not bury it: the seed needs light to germinate, so press it onto the surface and cover only lightly to 5 mm. Keep trays humid and around room temperature until the fine seedlings appear. Harden plants off gradually and only plant out once nights are reliably mild, since a late frost around Melbourne will flatten them overnight.

The usual failure is wilting and flower drop in a hot, dry spell. Impatiens has thin, water-hungry stems and collapses fast when the soil dries, especially in a Sydney heatwave. The fix is a moisture-retentive, compost-rich bed, a good mulch, and consistent watering; plants recover from a mild wilt but repeated stress ruins the display.

Watch too for downy mildew, which has troubled the older bedding impatiens badly. If you have lost plants to sudden collapse and yellowing before, choose mildew-resistant New Guinea types or the newer bred lines. Pinch young plants once to encourage a bushier, better-flowering habit.

Impatiens at a glance

Common questions

Can impatiens grow in full shade?

Yes, impatiens is one of the best flowering plants for shade and will bloom happily where most bedding plants sulk. Morning sun with afternoon shade is ideal, and deep shade under trees still produces a reasonable display.

When can I plant impatiens out in Melbourne?

Wait until frost danger has passed, generally from mid-spring, since impatiens is frost tender and a late Melbourne frost will kill young plants overnight. Harden seedlings off first, then set them out when nights are reliably mild.

Why do my impatiens keep wilting?

Impatiens has water-hungry stems and collapses quickly when the soil dries, particularly in a heatwave. Improve the bed with compost, add mulch, and water consistently; plants recover from mild wilting but repeated stress spoils flowering.

How do I stop impatiens getting downy mildew?

Older bedding impatiens are prone to downy mildew, which causes sudden collapse and yellowing. Choose mildew-resistant New Guinea types or newer bred lines, and give plants good airflow rather than crowding them.

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