Kohlrabi/Kohl Rabi Seeds

How to Grow KohlRabi

The essential guide to growing kohl rabi from seed; with notes on germination, cultivation, harvest and even kitchen uses. One of the kookiest and grooviest looking vegies out there!!

Meet the Kohlrabies – Flavour & Kitchen Uses

• Green / White-skinned – crisp, juicy and mildly sweet; grate raw for slaws, slice for crudités or dice into stir-fries.
• Purple-skinned – same flavour as green but eye-catching colour that holds when lightly steamed; lovely roasted with herbs.
• Giant / Storage types (e.g. ‘Kossak’) – bred for late-season harvest; dense flesh ideal for soups, mash or slow braises and stores for months.
• Leaf use – young tops cook like kale or silverbeet; a bonus crop of tender greens.

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Seeds per Gram: ~250 – 300 seeds

Germinating Temperature: 16 – 27 °C (emergence in 7 – 10 days)

Feed Requirements:

• Moderate feeder.
• Work 5 cm of compost plus a balanced organic fertiliser into the bed before sowing.
• Half-way to harvest: apply a liquid seaweed or fish emulsion to keep stems swelling quickly.

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Growing Notes:

Climate & Timing

• Temperate & cool zones: sow late summer-autumn for spring harvest, or late winter-early spring for early summer harvest.
• Sub-tropics: sow autumn-winter only; avoid humid summer heat.
• Frost tolerance: mature plants handle –4 °C and taste sweeter after light frosts. Hot weather (>28 °C) slows growth and causes woody bulbs.

Sowing & Spacing

• Direct-sow 5 mm deep, spacing seeds 10 – 20 cm apart in rows 30 – 40 cm apart; thin to strongest plants once true leaves show.
• For transplants, start seed 4 – 6 weeks early; set out when seedlings have 6-8 leaves and nights stay above 8 °C.
  

Soil & Water

• Prefers fertile, well-drained loam, pH 6.5 – 7.5.
• Keep the top 5 cm of soil evenly moist.
• Mulch to conserve moisture and suppress weeds.

Care

• Net young plants to exclude cabbage white butterflies and pigeons.
• Remove lower yellowing leaves to improve airflow.
• Bulbs maturing in mid-summer become woody.

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Common Problems & Fixes:

• Woody or hollow bulbs: usually heat, drought or over-maturity – sow at the right time, water consistently and harvest young (5 – 7 cm for tender types).
• Bolting: triggered by cold shock in seedlings or prolonged heat; harden off transplants, maintain steady growth, choose bolt-resistant cultivars.
• Cabbage moth/caterpillars: exclude with insect mesh, hand-pick or spray dipel.
• Aphids: hose off, or apply insecticidal soap; encourage ladybirds.
• Slugs & snails: use beer traps or iron-based pellets, especially around seedlings.

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Harvesting:

• Harvest bulbs when 5 – 7 cm across for salad-grade tenderness, or up to 10 cm for cooking.
• Cut just below the swollen stem, leaving the fibrous taproot in the ground.
• Young leaves can be picked any time.

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Storage & Use:

• Trim leaves, then store bulbs in a perforated bag in the refrigerator for up to two weeks.
• For long keeping, blanch cubes and freeze, or pickle thin slices in a light vinegar brine.

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Give kohlrabi cool temps, steady moisture and rich soil, and this space-saving brassica will reward you with crunchy, apple-sweet stems and bonus greens through much of the year.