When to plant Kohlrabi in Temperate Australia

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

Kohlrabi is one of the most forgiving brassicas for succession, and in the temperate zone you can sow direct across almost the whole year, from January through to December with only a short winter pause. Seed germinates fast in 6–12 days, so sow shallow at 6 mm and thin early. Space plants 10–20 cm apart with 30–40 cm between rows to let the swollen stems form cleanly above the soil. Maturity is quick at 55–70 days, which makes it ideal for filling gaps between slower crops. In temperate gardens around Melbourne, Adelaide and Perth, small regular sowings keep the crisp bulbs coming.

Sowing calendar — temperate zone

Green months are your sowing window: August to May.

Growing notes

Kohlrabi is a brassica grown for its swollen stem rather than a head or root, and its speed is its great advantage. Because it matures in as little as 55 days, it fits neatly between longer crops and rewards little-and-often sowing rather than one big planting that all matures at once.

Grow it in full sun in a fertile, moisture-retentive bed. Even, steady watering is the whole game: the classic failure is a woody, split or bitter bulb caused by inconsistent moisture and heat stress. If plants dry out and then get a heavy soak, the bulbs crack. The fix is consistent watering, a good mulch, and harvesting promptly at tennis-ball size rather than letting bulbs get oversized and tough. In a hot Perth or Adelaide summer, favour the milder shoulder seasons for the sweetest, most tender results.

As a brassica, kohlrabi can attract cabbage white butterfly, whose green caterpillars chew the leaves. Watch for the white butterflies from spring, and either pick caterpillars off by hand or cover young plants with fine mesh. Damage to leaves matters less here than in leaf brassicas, since you eat the stem, but heavy infestations still set plants back.

Harvest by slicing the bulb off at the base while it is still crisp and mild.

Kohlrabi at a glance

Common questions

Why is my kohlrabi woody and tough?

Woody, split or bitter bulbs come from inconsistent watering and heat stress, and from leaving bulbs to grow oversized. Water steadily, mulch well, and harvest promptly at tennis-ball size for tender, sweet stems.

How long does kohlrabi take to grow?

Kohlrabi is fast, maturing in just 55–70 days from sowing. That quick turnaround makes it perfect for succession sowing to fill gaps between slower vegetables.

Can I grow kohlrabi all year in Melbourne?

Almost. Melbourne's temperate climate allows sowing across most of the year with only a short winter pause. Small regular sowings give you a steady supply rather than a glut.

Do I eat the leaves or the bulb of kohlrabi?

You eat the swollen stem, which sits above the soil like a bulb, though the young leaves are also edible cooked. Slice the bulb off at the base while it is still crisp and mild.

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