When to plant Marrow in Subtropical Australia

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

Sow marrow direct from August to February, placing the large seed 20–25 mm deep into warm, fertile, well-drained soil. This frost-tender cucurbit thrives in subtropical warmth around Brisbane and the Sunshine Coast, so the main season runs from late winter through summer once the soil has warmed. Seed germinates fast in 7–14 days and plants sprawl quickly, so give them room: space 60–90 cm apart with rows 90–120 cm apart. Marrows are ready in 70–100 days, cropping heavily once they start. Water deeply and feed well, because these are hungry, thirsty plants that reward rich ground with a steady flush of long, mild-flavoured fruit.

Sowing calendar — subtropical zone

Green months are your sowing window: August to February.

Growing notes

Marrows are essentially mature zucchini and grow with the same vigour, which in the subtropics means fast growth but high pest and disease pressure. Give each plant a full, sunny bed enriched with compost, keep water up in dry spells, and they will romp away. The trouble usually comes from humidity and the pests it favours.

Powdery mildew is the near-certain failure mode here, coating leaves with white powder in humid Gold Coast and Lismore summers and cutting yields short. Space plants at the full 60–90 cm for airflow, water at the base in the morning rather than over the leaves, and remove the worst-affected lower leaves as they appear.

The second common problem is poor fruit set, where tiny marrows yellow and rot at the tip. This is failed pollination, common in wet weather when few bees are flying. Hand-pollinate in the morning by brushing pollen from a male flower into the females, which have a small fruit behind the bloom. Watch for chewing damage from cucumber beetles and the 28-spotted ladybird, and for stem borer at the base. Harvest young and often to keep plants productive.

Marrow at a glance

Common questions

when to plant marrow in Brisbane

Sow direct from August to February, once the soil has warmed. The frost-tender plants love subtropical heat, so late winter through summer is the main season, with the fastest growth in the warmer months.

why are my marrows rotting on the plant

Small fruit that yellow and rot at the tip are usually poorly pollinated, which is common in the wet when few bees are about. Hand-pollinate in the morning by transferring pollen from a male flower to the female blooms that have a tiny fruit behind them.

how do you stop powdery mildew on marrows

Powdery mildew is almost inevitable in humid subtropical summers. Slow it by spacing plants for airflow, watering at the base in the morning rather than over the leaves, and removing badly affected lower leaves as they appear.

how much space does a marrow plant need

A lot. Space plants 60–90 cm apart with rows 90–120 cm apart, because they sprawl vigorously and need airflow to fend off disease in the humid subtropics.

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