Leeks

Leeks are a member of the onion (allium) family and are possibly the easiest of the alliums to grow.

They take a long time to grow. You sow them in February and start harvesting them from late autumn right through the winter. I am still harvesting last year's crop as I sow new seeds for the coming year!

Cultivation

Leeks can be grown in most types of soil, although they will not grow well in soil that is very compacted or badly drained.

They will thrive best in soil that is well dug over and rich in nutrients, so ideally you should dig in well-rotted manure or compost in the autumn to prepare the soil for the spring planting. I have also had good results planting leeks in raised beds filled with decent compost, although leeks don't really need such special treatment.

Leeks are others in the three-year crop rotation scheme.

Leeks are grown from seed. I usually sow mine around mid-February in seed trays in the greenhouse.

They initially grow into thin green stems similar to chives or young spring onions. When they get to 10cm tall, I transplant them individually into small pots to grow on.

They can be planted out in late May. By that time they should be about 20cm tall and the thickness of a pencil. It is important to make sure most of the stem is below ground level. The part of the leek that is underground will remain white, and that is the edible part. The part of the leek that is above ground level will form the green leaves. These are necessary for the leek to grow, of course, but the leaves are usually too tough to eat.

Use a dibber to make a hole about 15cm deep and place one leek plant in each hole. You can fill the hole with water to bed the leek in, but you should not fill the hole with soil. This allows the leek to expand unrestricted (if you fill the hole with soil that can prevent the leek from growing to a good size).

Varieties

Musselburgh is a popular variety in the UK. It is reliable and hardy, with shorter, thick stems.

Below Zero F1 Hybrid is a variety I am trying for the first time in 2025. It is supposed to be a vigorous variety that thrives in cold conditions.

Pests and diseases

There are a few viruses and insect pests that can affect leeks, but personally, I have never had any problems growing leeks. If you ensure that the soil is reasonably well drained and use crop rotation, they are usually a problem-free crop.

Culinary uses

Leeks can be used in cooking, for example in soups or stews, in a similar way to onions. Discard the dark green leaves and the roots. The white and light green parts of the stem can be sliced. Soil often gets trapped between the outer rings towards the top of the stem, it is important to wash the leek carefully and check for any trapped soil.

Leeks can be kept for a week or so in the fridge, but they don't store well for longer periods. They are best left in the ground until they are needed. They can stay in the ground until around April of the year after they were planted.