Leek (allium porrum)

Why plant

Easy to grow

Use own seeds from previous season

Delicious! With a more delicate and sweeter flavour than onions, leeks add a subtle touch to recipes without overpowering other flavours present.

One of the few vegetables to harvest during winter and if planned right can harvest from late summer right through to spring, so harvesting while the next season’s batch is growing

Interesting uses

The leek is worn on St David’s Day as one of the national emblems of Wales along with the daffodil (known in Welsh as "Peter's Leek"). According to legend King Cadwaladr ordered his soldiers to wear leeks on their helmets in an ancient battle that took place in a field of leeks to differentiate themselves against their Saxon foes. Shakespeare refers to the custom of wearing a leek as an “ancient tradition” in Henry V. The leek is used as the cap badge of the Welsh Guards.

Origins

Most probably of Eastern origin, the leek was commonly cultivated in Egypt in the time of the Pharaohs from about 2000 BC. The Romans made great use of leeks for savouring their dishes and it’s referred to in a number of recipes. It’s likely the leek was brought to England by the Romans and by the 16th century it was commonly cultivated and used.

Health benefits

Being part of the same family as garlic and onions, leeks contain many of the same beneficial compounds found in these health-promoting vegetables.

Leeks contain important amounts of the flavonoid kaempferol, shown to help protect our blood vessel linings from damage, as well as a high concentration of the B vitamin folate which protects the heart. Also present are impressive concentrations of antioxidant polyphenols, which play a direct role in protecting our blood vessels and blood cells from oxidative damage.

For other likely benefits read the guides on garlic and onions.

Varieties

Musselburgh is the most common and easiest type to cultivate and is winter hardy to harvest from December to April.

Lyon, an autumn variety with mild-tasting long stems

Pandora crops between September and January

Planting

Sow seeds 1 inch (2.5 cm) apart in a seed tray from January onwards, covering lightly with compost, to produce plants for transplanting in April and harvesting from late summer onwards. The seeds germinate easily in reasonable temperatures.

 

Gradually harden off from mid March to April by moving to a cold frame or greenhouse before planting outside. Plant in their final positions in April when 6-8 inches (15-20 cms) high. Leeks do best with a long season of growth so the earlier they’re planted out the better.

Using scissors cut off the top quarter of the leaves and using a dibber make holes 6 inches (15 cms) deep and 9 inches (22 cms) apart, with rows 15 inches (38 cms) apart. Leeks should be planted deeply to whiten the stems, so drop the seedlings into the holes leaving just the tips of the leaves showing. Don’t fill in the holes or try to cover the roots with soil or even firm them in. Fill each hole with water and this will wash some soil over the roots just enough to tighten the little plants in. Over time the holes will fill up gradually from hoeing or rain.

Aftercare

Keep the leek bed moist in dry weather and hoe regularly to keep weeds down. After several weeks the holes the leeks were planted in will have filled up with soil; bank some more dirt up to the stems with a hoe to ensure you’ll have a good length of white stem. But do this earthing up gradually over a period of three weeks… if done too quickly the leeks may rot.

Harvesting

Leeks are one of the hardiest vegetables and can be left in the ground throughout autumn and winter. Just pull up as and when required.

To produce seeds for use in the following season just leave two or three plants to produce seed heads over the summer. At the end of summer cut off the seed heads and store in a paper bag, placing it in a dry place. When you’re ready to plant seeds you’ll have several hundred ready to go.

Recipes

Creamy chicken and leeks

Cheesy leeks and ham

Creamy ham, leek and mushroom spaghetti

Ham, leek and potato pie

Buttered leeks

Leek, bacon and potato soup

Roasted beets, leeks and onions

Leeks wrapped in parma ham and gruyere

Common problems

Leek rust is a common disease and occurs in most seasons. Mild infections are common and do little damage but severe infections may kill plants. Infections are clearly visible on leaves as orange or brown markings which may be round or elongated. They’re caused by a fungus and the markings contain millions of spores which spread easily by wind to neighbouring plants. Warm and humid conditions encourage the fungus to spread.

Rust can also infect other plants in the same family (the allium family) such as garlic or onions.

The incidence and spread of rust on leeks can be reduced by the following…

• Good hygiene on your plot… make sure that any infected plant material is removed from your site rather than composted
• Early action… as soon as you spot an infection remove infected plants, or infected areas of leaf, from your plot and wash your hands and anything else that might have been in contact with the infected plant tissue
• Increase spacing between leeks to allow better air flow and keep humidity from building up
• Improve drainage on your site since this will help keep humidity down
• Some some varieties have partial resistance, such as Ardea, Porvite, Splendid and Walton Mammoth
• Avoid excessive nitrogen inputs since lush growth caused by excessive nitrogen is more susceptible to rust infection; use compost rather than a synthetic fertiliser
• If your soil is low in potassium add a supplement such as a seaweed dressing or an organic tomato fertilizer
• Make sure leeks are planted as far away from last years growing site as possible.

Leek moth caterpillars feed initially as leaf miners in the foliage and you may see the damage as white leaf mines. As they grow larger the caterpillars bore into the stems of leeks and into the bulbs of onions, leaving the centres looking shredded and mushy. The moth has two generations during the summer, with the larvae active during May to June and again between August and October.

Watch out for pupae in their net-like silk cocoons on the leaves, and remove them by hand before the adult moths emerge.

Affected plants often get secondary rots entering the sites of damage and causing complete collapse of the plants; those that survive can still produce a reasonable crop.