Leeks are quite easy to grow and will withstand even the harshest winter. For many GIYers they are the only crop left in the soil during the winter months. You can grow a huge amount of leeks in a relatively small space. They are another of the classic stockpot vegetables. We eat the white part or stem of leeks – it is more accurately a rolled leaf rather than a stem (if you want to be pedantic about it).
Leeks are best grown in modules before being transplanted to their final growing position later. They are very easy to grow from seed. Sow one or two seeds per module just 1cm deep (they are a small, black seed). They will take about two weeks to germinate. For a continuous supply of leeks sow as follows:
February – plant out in April, will be ready to eat in early autumn
March – plant out in May, will be ready to eat in early winter
May – plant out in June, will be ready to eat in late winter
Leeks are heavy feeders so it’s best to grow them in fertile soil that has been enriched with plenty of farmyard manure or compost. Spread a general purpose organic fertiliser before planting out. They will be ready to plant out about 2 months after sowing (when they are pencil thick). The process of planting leeks is called “puddling in” and feels a little counter-intuitive but works very successfully. Here’s how it works: Make a 6-inch hole with a dibber, drop the leek in and then fill the hole gently with water. Do not backfill with soil – over the coming weeks it will fill itself (see, I told you it would feel counter-intuitive!). Leave 15cm between plants and 30cm between rows. Keep the leek bed well weeded. Some people advise snipping the root and top before planting but this can reduce yields.
Leeks have to be earthed up during the growing season – this process encourages the bleaching or whitening of the stem. If you don’t earth up you will be left with leeks which are predominantly green with just a small amount of edible white stem. Earth up twice during the season.
The best leeks are the small tender ones – they decrease in flavour as they grow larger, so don’t aim to produce prize-winning ones. Lift the leek with a fork – their roots are surprisingly fibrous and strong. Winter varieties can stay in the ground until needed, they are practically indestructible.
Leek rust is an issue – it’s an airborne fungus that affects all the allium family, particularly garlic. Though the leeks look unattractive when infected, it doesn’t in fact affect the taste at all. You can try cleaning them carefully, but this doesn’t work in my experience. Leeks can also get white rot, which is why you should include them in your allium rotation.