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How to grow and harvest leeks

Close up of leeks in the soil.
Leeks are a sweeter and milder cousin of the common onion. They don’t form a bulb but their thickened white stems are full of flavour and they’re a wonderfully versatile vegetable to include in your kitchen garden.

What you need to know about leeks

Name: leek, Allium porrum.

Height: 60-120cm.

Plant type: biennial vegetable, but usually grown as an annual.

Climate: suitable for all zones.

Soil: moist, well drained and enriched with plenty of organic matter.

Position: full sun.

Foliage: fan-like sheaf of flattened blue-green leaves with thickened white ‘stems’.

Flowers: elegant, globe-shaped heads of purple or white flowers on long, slender stems.

Feeding: liquid feed regularly throughout the growing season.

Watering: water regularly to keep the soil moist.

Appearance and characteristics of leeks

Leeks are a member of the onion family, but have a sweeter and milder flavour than the common onion. Unlike most members of the family, leeks don’t form a bulb, but rather a thickened ‘stem’ which is actually a tight bundle of leaf sheaths. Long white stems are encouraged by ‘earthing up’ or mounding the soil around the base of the plants. While leeks are generally grown for their stems, the leaves and flowers are also edible.

Spheres of white or purple flowers appear in spring and, although decorative, are not desirable if you’re growing leeks to eat, as flowering causes the stems to become woody, tough and bitter.

Close up of leeks with roots showing on a wooden cutting board.

Uses for leeks

Leeks are a versatile veggie that are often used as a substitute for onion. Use them to flavour soups, casseroles, risotto, pasta, pies or any recipe that calls for onions. They are also delicious roasted on their own or with other vegetables.

How to grow leeks

While leeks are widely considered to be a cool-season crop, they can be grown year-round in most climates, but avoid sowing or planting in extreme hot or cold conditions. Prepare the garden bed at least a couple of weeks prior to planting. Choose a spot in full sun with well-drained soil and mix in plenty of organic matter, including compost and well-rotted manure, and fork in well.

Dig a trench or individual holes spaced 15cm apart. Sow seed or plant seedlings in the prepared area and water regularly to keep the soil moist.

Caring for leeks

Leeks need regular watering to keep the soil moist. Spread an organic mulch, like pea straw or compost , over the surface of the soil to help conserve moisture.

Encourage leeks to produce longer and whiter stems (which makes them sweeter ) by ‘earthing’ or mounding up the soil around the base of the plants a few weeks prior to harvesting. Stems can also be blanched by securing a piece of cardboard around the base of each plant.

A bunch of trimmed leeks on a white background.

How often should you water and feed leeks?

Water often to keep the soil moist. This may mean watering once daily or once every couple of days, depending on your local climate. Adding mulch will help reduce watering frequency.

Feed weekly or as directed with an organic liquid fertiliser.

How and when to harvest leeks

Leeks usually take up to five months to fully mature from seed but can be harvested when the stems are 2cm thick. Plants grown from seedlings are generally ready in three to four months. Use a sharp knife to cut plants at the base and, ideally , cook and consume them on the same day.

Diseases and pests that affect leeks

Snails and slugs can sometimes be a problem. Use physical barriers or traps, or sprinkle an organic snail and slug bait around garden beds.

How to propagate leeks

Leeks are generally grown from either seed or seedlings. However, it is also possible to grow them from ‘scraps’ from store-bought produce. To do this, the stems must have roots intact. Remove the leaves and most of the stem, leaving a 5-10cm section of stem with roots. Sit the stem, roots down, in a shallow glass of water and place in a warm, brightly lit spot, out of direct sunlight. Change the water once every few days. After a week, new leafy growth will emerge from the centre of the base. After 10-14 days, more growth will have developed and it can be planted in a prepared garden bed. Ensure you plant at the right time for your climate zone.

If you like this, then try

Bok choy: a fast-growing Asian vegetable that’s ready to harvest in 6-8 weeks.

Oregano: this fragrant herb also doubles as a fabulous ground cover.

Horseradish: a vigorous vegetable with pungent, aromatic roots.

Start planting today

Check out our wide range of plants now and get your garden growing!

 

Photo credit: Getty Images

Health & Safety

Please make sure you use all equipment appropriately and safely when following the advice in these D.I.Y. videos. You need to be familiar with how to use equipment safely and follow the instructions that came with the equipment. If you are unsure, you may feel it is safest to consult an expert, such as the manufacturer or an expert Bunnings Team Member.

Grave health hazards are linked to asbestos, which may be in homes built up to 1990. Health hazards may result from exposure to lead-based paints in older materials and copper chromium arsenic (CCA) treated timber. For information on the dangers of asbestos, lead-based paint and CCA treated timber and tips for dealing with these materials contact your local council's Environmental Health Officer.