Introduction
Leeks are a versatile and hardy vegetable, perfect for growing in the southeast of the UK. With their mild, onion-like flavour, they are a staple in many soups, stews, and casseroles. Growing leeks can be a rewarding experience, providing you with a bountiful harvest throughout the autumn and winter months.
Why grow leeks?
Leeks are a good source of vitamins A, C, and K, as well as minerals like iron and manganese. They are relatively easy to grow and can withstand cold weather, making them an excellent winter crop. Growing your own leeks ensures they are fresh and free from pesticides.
Suitability for different growing environments
Leeks prefer well-drained soil with plenty of organic matter. They thrive in full sun but can tolerate light shade. Leeks are best grown directly in the ground, but they can also be grown in deep containers if space is limited.
Lifecycle
Leeks are biennial plants typically grown as annuals. They are sown in spring and harvested from late autumn through winter. The plants develop long, thick stems over the summer, which can be harvested as needed throughout the colder months.
Sowing and harvesting periods
- Sowing: Early spring (March to May)
- Harvesting: Late autumn to early spring (October to March)
Recommended varieties
Some popular leek varieties include:
- ‘Musselburgh’
- ‘Bandit’
- ‘Blue Solaise’
- ‘Autumn Giant’
How to sow
Sow leek seeds in early spring in seed trays or modules. Fill the trays with seed compost, sow the seeds thinly, and cover with a thin layer of compost. Keep the soil moist and place the trays in a sunny, sheltered spot or in a greenhouse. Once the seedlings are about 6 inches (15 cm) tall, they are ready to be transplanted.
How to prick out/pot on
When the leek seedlings are large enough to handle, transplant them into individual pots or larger modules. Allow them to grow on until they are pencil-thick and ready to be planted out into their final positions in the garden.
Where to plant
Choose a sunny spot with well-drained soil that has been enriched with compost or well-rotted manure. Leeks do well in soil that has been used for legumes or brassicas the previous season, as these crops improve soil structure and fertility.
How many to plant (spacing)
Space leeks 6 inches (15 cm) apart in rows that are 12 inches (30 cm) apart. This allows enough room for the plants to grow large, healthy stems without overcrowding.
How to plant
To plant leeks, make holes 6 inches (15 cm) deep using a dibber or a similar tool. Drop the seedlings into the holes without filling them in with soil. Water the holes well; this will help the soil settle around the roots. The holes will gradually fill in as the plants grow.
Protecting your plants
Leeks are relatively hardy, but young plants can be susceptible to pests like leek moth and allium leaf miner. Use fine mesh or fleece to cover the plants and protect them from these pests. Ensure good air circulation to prevent fungal diseases.
How to feed and water
Leeks benefit from regular watering, especially during dry spells. Keep the soil consistently moist but not waterlogged. Feed the plants with a balanced fertiliser every few weeks to encourage strong growth.
How to propagate, prune/manage while growing
Leeks are propagated from seed. They do not require pruning, but regular weeding is essential to reduce competition for nutrients and water. Earth up the soil around the stems periodically to blanch them, which results in a longer, tender white shaft.
How and when to harvest
Harvest leeks from late autumn through to early spring, depending on the variety and when they were sown. Use a fork to lift the leeks gently from the soil to avoid damaging the roots. Leeks can be harvested as needed, and they will keep well in the ground until you are ready to use them.
How to store
Store harvested leeks in a cool, dark place. They can be kept in the ground and dug up as required or stored in a box of damp sand in a shed or garage. Leeks will keep for several months if stored correctly.
How to eat/cook
Leeks can be used in a variety of dishes, including soups, stews, casseroles, and quiches. They can be sautéed, roasted, or grilled, adding a mild, onion-like flavour to your meals. To prepare, simply wash, trim the roots and green tops, and slice as needed.
How to deal with pests and disease
Common pests include leek moth, allium leaf miner, and slugs. Use organic methods to manage these pests, such as fine mesh covers and hand-picking slugs. Watch for diseases like rust and downy mildew. Practise crop rotation and good garden hygiene to minimise the risk of disease.
When and how to remove the plants
Remove any remaining plants in early spring before the new growing season begins. Dig up the roots and compost any plant material. Clean the bed thoroughly to prepare it for the next crop.
What to plant before and after
Leeks can follow crops that improve soil structure, such as legumes or brassicas. Avoid planting after other alliums to reduce the risk of soil-borne diseases. After harvesting leeks, consider planting leafy greens, root vegetables, or legumes to make the most of the soil’s improved structure and nutrient content.
What to interplant with
Good companion plants for leeks include carrots, celery, and onions. These plants help deter pests and do not compete heavily for nutrients or space. Avoid planting leeks near beans and peas, as they can inhibit each other’s growth.