When to plant Evening Primrose in Subtropical Australia

Subtropical zone — applies to Brisbane, Gold Coast, Sunshine Coast, Coffs Harbour, Lismore and similar areas. Growing elsewhere? Temperate · Cool · Tropical · Arid.

Raise evening primrose seedlings from April to September, sowing into trays or punnets and transplanting once they have a couple of true leaves. In subtropical gardens the cooler, drier months give the steadiest start, and the tiny seed needs only about 1 mm of cover. Germination is slow at 21–28 days, so keep the mix warm and lightly moist without letting it stay wet. This is a biennial that takes close to a full 12 months to flower, so plant it where it can stay put. Space plants 30 cm apart in rows 30–60 cm apart, in full sun.

Sowing calendar — subtropical zone

Green months are your sowing window: April to September.

Growing notes

Evening primrose is easy-going once established, but the subtropical wet is its main enemy. Around Brisbane and the Gold Coast, summer humidity and downpours cause crown rot and powdery mildew on crowded plants, which is why an autumn-to-spring sowing pays off — the rosette bulks up over the mild winter and flowers before the worst of the wet arrives.

Give it a raised bed or a slope so water drains away from the crown. Full sun keeps the foliage dry and the flower spikes strong; in shade the plant stretches and flops.

• Water at the base, not over the leaves, to reduce mildew.
• Mulch lightly, keeping it clear of the crown.
• Don't overfeed — rich nitrogen gives soft growth that rots.

The most common failure here is sowing too late and hitting summer rain before the plant has matured; seedlings drown or damp off. Stick to the cooler window and thin early so air moves freely between plants. Once flowering, it self-seeds readily, so pull unwanted volunteers while they are small.

Evening Primrose at a glance

Common questions

When should I plant evening primrose in Brisbane?

Sow from April through September, raising seedlings in the cooler, drier part of the year. This gives the biennial rosette time to establish over winter before flowering, and avoids starting plants into the summer wet when rot is most likely.

Why is my evening primrose not germinating?

The seed is naturally slow, taking 21–28 days, and it is very fine — sow no deeper than 1 mm. Cold, wet mix or being buried too deep are the usual causes of failure. Keep the surface warm and just moist and be patient.

Does evening primrose flower in its first year?

Usually not. It is a biennial that needs close to 365 days to reach flowering, forming a leafy rosette first and sending up flower spikes the following season. Plant it somewhere it can stay undisturbed for a full year.

How far apart should I space evening primrose?

Space plants about 30 cm apart, with rows 30–60 cm apart. In humid subtropical gardens the wider spacing helps air circulate and keeps powdery mildew down.

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