When to plant Mustard in Temperate Australia

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

Sow mustard direct in almost any month of the year, from January right through to December, setting the seed about 6 mm deep in moist, fertile soil. This hardy, fast leafy brassica suits the temperate climate across all four seasons, germinating in 6–12 days and ready to use in a quick 30–60 days. Space plants 30–40 cm apart, with rows 40–60 cm apart, or grow them closer for cut-and-come-again leaves and green manure. Melbourne, Adelaide and Perth gardeners rely on mustard as a year-round standby, using it for peppery salad leaves, cooking greens, and as a quick soil-improving cover crop between other plantings.

Sowing calendar — temperate zone

Green months are your sowing window: January to December.

Growing notes

Mustard is about as easy and adaptable as leafy crops get, which is why its temperate sowing window runs right across the year. Its 6–12 day germination and 30–60 day turnaround make it perfect for filling gaps, and as a hardy plant it copes with both cool and warm spells better than most greens.

The main failure mode is bolting and heat-driven bitterness. In the peak of a hot Adelaide or Perth summer, mustard sown for leaf can run to flower quickly and the leaves turn fiercely hot and coarse. The fix is to lean summer sowings towards cooler, shadier spots, keep the water up, and harvest young; save the main leaf crops for the milder months either side of summer.

Mustard has a second, quieter role as a green manure. Sown thickly and dug in before it flowers, it adds organic matter and its residues have a mild biofumigant effect that can suppress some soil pests and diseases, useful in a bed being rested between crops. If you are growing it for leaf instead, honour the wider 30–40 cm spacing for full plants. Like other brassicas it can attract caterpillars and flea beetle, so netting keeps salad leaves clean in a Newcastle or Sydney spring. Water consistently, feed lightly, and pick outer leaves regularly to keep plants going.

Mustard at a glance

Common questions

Can I grow mustard all year round in Melbourne?

Yes, mustard is hardy and adaptable enough to sow in any month in a temperate climate. It germinates in 6–12 days and matures in 30–60 days, though the mildest crops come from the cooler months either side of summer.

Why is my mustard so bitter and hot?

Heat and bolting make mustard leaves fiercely peppery and coarse. Grow it in cooler months or a shadier spot in summer, keep the water up, and harvest the leaves while young for a milder flavour.

How do I use mustard as a green manure?

Sow it thickly, let it grow leafy, then dig it into the soil before it flowers. It adds organic matter and has a mild biofumigant effect that can help suppress some soil pests and diseases between crops.

Do I need to protect mustard from pests?

As a brassica it can attract caterpillars and flea beetle that hole the leaves. Lightweight exclusion netting over the bed keeps salad crops clean, especially through the warmer spring and summer months.

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