When to plant Marrow in Temperate Australia

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

Sow marrow direct from September to December, with a further window in January and February, dropping the large seed a deep 20–25 mm into warm, well-fed soil. This is a fast, frost-tender cucurbit for the warm half of the temperate year, germinating in 7–14 days and reaching harvest in about 70–100 days. Give it serious room, 60–90 cm between plants and 90–120 cm between rows, because a single marrow plant sprawls widely. Melbourne, Adelaide and Perth gardeners sow once frost has passed and enjoy a heavy crop of large, mild-fleshed fruit through late summer and autumn from just a plant or two.

Sowing calendar — temperate zone

Green months are your sowing window: September to February.

Growing notes

Marrow is essentially a courgette left to mature, and it grows the same way: fast, hungry and thirsty, on rich soil in full sun. Because it is frost tender, wait until spring frosts are gone before the main September to December sowings, or use the January and February window for a later crop. Sow the seed on its edge at 20–25 mm deep to reduce rotting.

The most common failure in temperate gardens is poor fruit set: flowers form and then drop or rot at the tip. This is usually a pollination problem, made worse by wet, cool weather or a lack of bees. Hand-pollinate on a dry morning by brushing a male flower into the open females, and set is quickly restored. Powdery mildew is the other reliable menace in a humid Sydney or Newcastle summer; water at the base, space plants at the full 60–90 cm for airflow, and remove badly affected leaves.

Feed generously, because marrows are heavy croppers. Dig in plenty of compost or aged manure before sowing and side-dress once fruit sets. Keep the soil evenly moist to avoid bitter, misshapen fruit, and mulch well to hold water through hot Adelaide and Perth spells. Pick some fruit small as courgettes and let others swell to full marrow size; regular picking keeps the plant productive.

Marrow at a glance

Common questions

When do I plant marrow in Perth?

Sow direct from September to December once frost has passed, with a later option in January and February. Warm soil is essential, so wait for settled spring weather before sowing the seed 20–25 mm deep.

Why are my marrow flowers falling off without fruiting?

This is usually poor pollination, common in cool, wet weather or when bees are scarce. Hand-pollinate on a dry morning by transferring pollen from a male flower to the open female flowers, and fruit set should improve quickly.

What's the difference between a marrow and a courgette?

They are the same type of plant; a marrow is simply a courgette allowed to grow large and mature. You can pick fruit young and small as courgettes, or leave them to swell to full marrow size for stuffing and baking.

How much space does a marrow plant need?

A lot. Allow 60–90 cm between plants and 90–120 cm between rows, because each plant sprawls widely. Crowding reduces airflow and encourages powdery mildew, so give them the room the spacing suggests.

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