I love leeks. What’s this often-unsung hero all about? From growing tips to nutrition.
Elegant, elongated with a mild onion flavour, leeks are a staple in New Zealand kitchens and gardens throughout winter. The leek is a cultivar of the broadleaf wild leek (Allium ampeloprasum), and is the largest vegetable cousin of garlic, chives, spring onions, onions, and shallots. Leeks are more subtle in taste to their pungent onion relative and add a savoury sweetness to food without overpowering other flavours.
Leeks arrived in New Zealand with settlers from the British Isles. Historically, they were cultivated by ancient Egyptians and were highly prized by the Romans. In Wales, the leek is a national symbol, worn on Saint David’s Day and linked to historic battles and Welsh identity.
In New Zealand, leeks are sown from early spring and harvested throughout the autumn and winter, with peak availability in June and July. They are well-suited to our cool, moist climates and thrive in loose, fertile soil. The plants take several months to mature and are ready to harvest when they reach 2–3 cm in diameter, although smaller ‘baby leeks’ are also prized for their tenderness. I love to use early, baby leeks interchangeably with late-planted spring onions.
The best growing conditions for leeks include full sun, and rich, well-drained soil with plenty of compost. They require regular watering and benefit from a technique called blanching — mounding soil around the stems to keep them tender and pale. This process not only gives leeks their classic white base but also improves the flavour. To harvest, gently loosen the soil and pull up the plant by the base. Leeks can be stored in the fridge for several weeks, or left in the garden and harvested as needed, even in frosty conditions.
Leeks pack a punch nutritionally. Nature again provides the right vegetables (and fruits) at the right time of year to support human health. They are dense in fibre, but it’s the sulphuric smell of all alliums where the nutritional magic lies. This distinct smell acts as an insect deterrent while the vegetable is growing and is a delight for the gut microbiome when it’s eaten. These sulphuric compounds have antibacterial, antifungal and antiviral properties. The rich antioxidants of leeks (polyphenols and kaempferol) are heart-protective and have anti-inflammatory effects. These sulphur compounds (such as allicin) not only support cardiovascular health but also immune function.
Other health benefits of leeks are:
- Vitamin K – for blood clotting and bone health
- Vitamin A – supports vision and immune function
- Vitamin C – helps with collagen formation and immune defense
- Folate – for cell growth and development
- Manganese and iron – supports metabolism and red blood cell production
Most of these nutrients are concentrated in the lower white and light green portions of the leek. The more fibrous darker green tops are great in stocks, soups, or even finely chopped into stir-fries. Cooking leeks lightly — by sautéing, steaming, or slow roasting — preserves their medicinal qualities while softening their texture and enhancing their sweetness.
To maximize iron and vitamin A absorption, pair leeks with a source of vitamin C (like lemon juice or capsicum) or healthy fats such as olive or coconut oil.
Leeks are especially popular and well matched in potato and leek soup, a classic winter delight. Roasted leeks make a fantastic side dish, and combine beautifully with cheese, mustard, and herbs like thyme and tarragon.
Before cooking, always rinse leeks thoroughly. Their layered structure can trap soil and grit, particularly between the white and green sections. Slice them lengthwise and soak in water to remove any debris.