When to plant Sweetpea in Cool Australia

Cool zone — applies to Hobart, Canberra, Ballarat, Orange, Armidale and similar areas. Growing elsewhere? Temperate · Subtropical · Tropical · Arid.

Sow sweet peas direct from January to April and again in September and October, planting the large seeds where the vines are to climb. Germination takes 7–21 days and the plants reach flowering in around 100 days, so an autumn sowing sets up strong roots for a spring show of scented blooms. Sow 10–20 mm deep, spacing seeds 5–10 cm apart along rows 30–45 cm apart against a tall support. Sweet peas are hardy and thrive on cool-season growth, making them a favourite for gardens in Ballarat, Orange and Canberra where the long cool spring extends the flowering.

Sowing calendar — cool zone

Green months are your sowing window: January to April and September to October.

Growing notes

Sweet peas are cool-climate flowers at heart, and an autumn sowing is the secret to the best display. Sown from January to April, seedlings build a deep root system through winter and burst into growth as spring warms, giving longer stems and more scent than a rushed spring sowing. Choose an open, sunny site with rich, well-limed soil, as sweet peas dislike acidity.

The most common failure is poor germination from hard seed coats and cold, wet ground. Some seed sits and rots rather than sprouting. Sowing 10–20 mm deep into a well-drained bed helps, and you can soak seed overnight or nick the coat to speed things along. Once up, pinch out the growing tip above the third pair of leaves to encourage strong side shoots.

A tall, sturdy support put in at sowing time is essential; these vines climb hard and flop badly without it. Late in the season, powdery mildew can grey the foliage as growth slows, so water at the base and keep airflow open with proper 30–45 cm row spacing. In frost-prone spots like Canberra, hardy plants take the cold, but pick flowers often, since the more you cut the longer sweet peas keep blooming.

Sweetpea at a glance

Common questions

when is the best time to sow sweet peas in cool climates

An autumn sowing from January to April gives the best results in cool zones, followed by a spring window in September and October. Autumn-sown plants build strong roots over winter and flower earlier and longer in spring. Both windows work, but autumn sowings are the show-stoppers.

why won't my sweet pea seeds germinate

Hard seed coats and cold, wet soil are the usual reasons seed sits and rots. Sow 10–20 mm deep into well-drained ground, and soak the seed overnight or gently nick the coat to help water in. Germination then takes 7–21 days.

should you pinch out sweet peas

Yes, pinch out the growing tip once plants have three pairs of leaves. This encourages strong side shoots and far more flowering stems. It is one of the simplest ways to improve the display.

do sweet peas need support in Ballarat

Yes, sweet peas are vigorous climbers and need a tall, sturdy support in any garden, including Ballarat. Put it in at sowing time, since the vines flop and tangle without it. A trellis, netting or teepee 1.5 m or more high works well.

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