How to Grow Leeks from Seed
Ground Prep
How and When to Sow Leeks
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Plant Care
Problems
Guide Chapters
- How to Grow
- Ground Preparation
- Sowing
- Plant Care
- Problems
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When to Sow: March and April
A stalwart, hardy and reliable winter vegetable plants, leek plants have many uses and taste great in everything from soups to pasta dishes. Their thick stems, known as shanks, have a versatile mild onion flavour and can be harvested when few other crops are still available. Seedlings thinned from the row even make an excellent salad vegetable.
Young leeks are often raised in a seed bed and then transplanted to their final growing positions. Their stems are blanched as they grow by regularly covering them with soil to make them white and tender. For really bumper crops, digging in plenty of garden compost or well-rotted manure in the autumn can improve the growing area.
To learn how to grow leeks from seed, read our detailed guide below, which features our experts’ best tips for growing these vegetable seeds to achieve wonderfully white stems.
You should choose a sunny spot with well-drained soil to give your leeks the best conditions for growing. Be sure to dig the soil over before planting leeks out, as leeks don't grow as well on compacted soil.
You should grow them in an area where you haven’t previously grown plants from the allium family (such as leeks, onion bulbs, shallot bulbs, and garlic bulbs), as this could increase the likelihood of disease.
You should sow leek seeds direct in the ground thinly in a seedbed, 1.5cm (half-inch) deep in rows 30cm (12in) apart from March to April. Afterwards, they are transplanted to the main growing area. This is done to save space in your garden and to give them the best chance of healthy growth in a controlled environment.
Thin seedlings to approximately 4cm (1.5in) apart when developed. The leek plants are ready to transplant to their final growing site from June when they are about 20cm (8in) tall and around the thickness of a pencil. Water well the day before lifting and transplanting. Prepare the plants by trimming off the root tips.
Make 15cm (6in) deep holes with a dibber. These holes should be 15cm (6in) apart in rows 30cm (12in) apart, then drop a plant into each hole. Fill the hole with water to settle the roots, and top up as necessary for the plants to establish.
Alternatively, leek seeds can be started indoors in trays of seed compost from January onwards, transplanting them outdoors when 20cm (8in) tall and after the last frost.
Leeks generally do better when grown in the ground, but they can be grown well in grow pots for those with limited space. They will still need a sunny spot with well-drained soil and a container with drainage holes to avoid waterlogging. They will need regular watering, as the soil is likely to dry out faster than when in the ground. Otherwise, the advice in this guide applies to container-grown leeks as it does to ground-grown leeks.
Keeping your leek plants blanched is essential to achieving the delicious white stems that they are characteristically known for. You should therefore gently mound up the dry soil around the plants to shield them from sunlight. This will prevent them from turning green, keep them white and tender and increase stem length. This also helps to keep your plants stable and protected from wind.
You should top up younger plants with water as necessary. Once established, leeks should be watered only when needed, specifically during dry spells. As mentioned above, leeks grown in containers will need more frequent watering as the soil can be prone to drying out quickly.
You should keep your growing area weed-free, as this will prevent your leeks from competing for resources. Be careful around the stems, an onion hoe or a narrow draw hoe will help to prevent damage to them. Don't allow soil to fall between the leaves when weeding, as this will make for gritty stems when harvested.
Unlike some other plants, leeks do not produce thick foliage that overshadows weeds once established. As a result, managing weeds effectively throughout their growth is important for their success.
A good layer of fertiliser or well-rotted manure will help plants reach their full potential by providing the nutrients they need. In addition, this can help to prevent weed growth and keep the soil beneath moist.
Growing leeks doesn’t usually pose too many problems, though there are one or two issues that have been known to affect plants. Below are the most common problems and methods on how to prevent or resolve them:
We conducted a survey to find out what our customers’ best advice is for growing leeks successfully. These tips can be found in our catalogues, but we’ve included them here to provide you with some extra information to take on board.
We haven’t tried out all of the tips below, but they provide insight into how others sow and grow their leeks that may come in handy.
Plant Expert
When Pim joined D.T. Brown, it was originally as a seed buyer, but now as our planting & sowing expert, he’s responsible for all horticultural and technical content, sharing his expertise in this catalogue, and through the growing advice and tips on our seed packets.
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