Leek — How to Grow Leek in Australia

☀️ Sun

Full Sun

💧 Water

Medium

↔ Spacing

15cm apart

↕ Height

Up to 50cm

📅 Harvest

150 days

Growing Guide

Plant leek seeds or seedlings during late summer to autumn (March to May) in most temperate and Mediterranean regions of Australia, or in late winter to early spring (July to September) in cool temperate areas like the Southern Highlands or Tasmania. Start seeds indoors 8–10 weeks before transplanting, sowing 6mm deep in seed trays filled with quality seed-raising mix. Prepare garden beds thoroughly by digging in generous amounts of aged compost and well-rotted manure to a depth of 30cm, as leeks are heavy feeders requiring rich, free-draining soil with a pH of 6.0–7.0. Transplant seedlings when they reach pencil thickness, approximately 15–20cm tall. Use a dibber or thick dowel to create 15cm-deep planting holes spaced 15cm apart in rows 30cm apart. Drop seedlings in and water well without back-filling — soil will naturally collapse around the roots over time. This deep planting encourages blanching of the lower shank. Water consistently at medium levels, keeping soil moist but never waterlogged. Mulch heavily with straw to retain moisture and suppress weeds. As plants grow, gradually mound soil up around shanks to extend the blanched white portion. Feed fortnightly with a balanced liquid fertiliser. Harvest leeks from 16–20 weeks when shanks reach 2–4cm in diameter by gently loosening soil with a fork and lifting carefully.

🤝 Good Companions

Leeks grow exceptionally well alongside carrots celery and brassicas such as cabbage and broccoli — carrots and leeks famously repel each other's pests (carrot fly and onion fly) through scent confusion. Celery improves overall bed health while brassicas benefit from the mild pest-deterrent qualities leeks provide through their allium compounds.

❌ Avoid Planting With

Avoid planting leeks near other alliums such as onions garlic and chives as they compete for the same nutrients attract identical pests and can increase the risk of shared diseases like white rot spreading through the bed. Legumes including beans and peas are also poor companions as allium compounds can inhibit their growth and nitrogen-fixing capacity.

🐛 Pests & Diseases

In Australian gardens, leeks are most commonly troubled by thrips, which cause silvery streaking on leaves, and can be managed with regular forceful water sprays and applications of neem oil or insecticidal soap. Leek rust, a fungal disease producing orange pustules on foliage, is a common issue in humid conditions and is best managed through good air circulation, avoiding overhead watering, and removing affected foliage promptly. White rot (Sclerotium cepivorum) can persist in soil for years, so rotate allium crops on a minimum 4-year cycle and avoid introducing infected plant material.

🌱 Fertilising

Apply a balanced slow-release fertiliser such as blood and bone or pelletised poultry manure at planting time, then supplement with fortnightly liquid feeds of a seaweed and fish emulsion blend throughout the growing season to support the leek's high nitrogen demands. As shanks begin to bulk up in mid-growth, transition to a potassium-rich liquid fertiliser to promote strong, flavoursome shank development.

✂️ Pruning & Training

Leeks do not require traditional pruning, but trimming the tops of seedling leaves by one-third at transplanting time reduces transplant stress and encourages the plant to direct energy into root and shank establishment. As plants mature, remove any yellowing or damaged outer leaves at the base to improve airflow, reduce disease risk, and keep the bed tidy.

🔬 Propagation

Leeks are most reliably propagated from seed, sown 6–8mm deep in seed trays during late summer or autumn, then transplanted into the garden when seedlings reach pencil thickness after approximately 8–10 weeks. Alternatively, purchase seedling punnets from a reputable nursery for a faster start, though growing from seed offers greater variety selection and is far more economical for larger plantings.

🗓 When to Plant

Autumn Winter

🌾 Harvest

Winter Spring

🌏 Australian Climates

Temperate Cool Temperate Mediterranean

More Vegetables

Tomato → Lettuce → Broad Bean → Spinach → Garlic → Pumpkin →