How to Grow Leeks in the UK
How to Grow Leeks in the UK
Quick facts
Sow: March–April outdoors (later varieties May–June), or indoors from late winter
Plant out: when seedlings are about 20 cm tall and roughly as thick as a pencil
Spacing: 15–20 cm apart, rows 30 cm apart (10 cm for baby leeks)
Time to harvest: about six months for full-size leeks, around two months for baby leeks
Harvest: late summer to the following spring, depending on the variety
Key moment: planting deep, which gives you long white stems
Leeks are one of the most dependable winter crops you can grow in the UK. They are slow, but they need very little from you once they're planted. And unlike most vegetables, they don't all need picking at once: hardy types stand in the ground through frost and snow until you want them.
How a leek crop runs through the year
Leeks spend a long time in the ground, so it helps to see the whole season before you start:
Late winter: sow indoors for an earlier crop
March–April: sow outdoors in a seedbed or straight into their final spot
May–June: sow later varieties for winter and spring harvests
Late spring to summer: plant out when seedlings reach about 20 cm
Late summer onwards: start lifting early varieties
Winter to spring: harvest hardy late varieties as needed
For exact timing in your area, see when to plant leeks in the UK
Choosing a leek variety
Leeks are split by when they mature. Early varieties are ready from late summer, mid-season ones through winter, and late ones hold on into spring. If you want leeks for as long as possible, grow one early and one late variety.
These varieties hold the RHS Award of Garden Merit:
'Stamford': early and quick to bulk up, a good choice for autumn leeks
'Porbella': thick white stems over a long picking season
'Krypton': compact plants ready from December
'Oarsman': a winter variety with resistance to leek rust
'Bandit': late, harvested through winter into spring
In colder parts of the north and Scotland, hardy winter varieties such as 'Oarsman' and 'Bandit' are the safer choice.
Preparing the ground
Pick a sunny, well-drained spot where you haven't grown leeks, onions or garlic for a few years. Keeping the onion family moving around the plot helps stop soil diseases building up.
Leeks will be in the ground for months, so give them a good start. Weed thoroughly, then dig in about two buckets of garden compost or well-rotted manure per square metre and rake the surface level. If you garden no-dig, spread the compost as a mulch and plant into it.
You can read more in best soil for vegetable gardening in the UK
Sowing leek seeds
Outdoors: in March or April, make a shallow drill about 1.5 cm deep. Water along the bottom first, then sow thinly and cover. If you're sowing more than one row, leave 30 cm between them. Cover early sowings with a cloche or fleece during cold snaps, because a chilly spring can make young leeks bolt (run to flower) later.
Indoors: from late winter, sow thinly into modules or small pots of seed compost, about 1.5 cm deep. Keep them somewhere bright and above 10°C. Move them into bigger pots if roots start poking out of the bottom. For timing across different crops, see when to start vegetable seeds indoors
Either way, seedlings take about two months to reach planting size.
Planting out: the step that makes a good leek
This is the part that matters most. A leek's white stem is the part buried away from the light, so the deeper you plant, the longer the white stem you'll get.
Plant out when seedlings are about 20 cm tall and roughly as thick as a pencil. Harden off any indoor-raised plants first (see how to harden off seedlings). Then:
Push a large dibber or an old trowel handle into the soil to make holes about 15 cm deep and 5 cm wide.
Space the holes 15–20 cm apart, with 30 cm between rows. For baby leeks, 10 cm apart is enough.
Lift the seedlings and trim the roots to about 2.5 cm with scissors. This makes them easier to drop in cleanly.
Drop one leek into each hole so only the top of the plant shows.
Fill each hole with water and leave it. This is called puddling in: the water washes a little soil down around the roots, and the hole fills in naturally over the following weeks. Don't push soil back in.
Watering, weeding and mulching
Water young leeks regularly until they're growing strongly. After that, leeks in the ground only need water during long dry spells. Aim at the soil, not the leaves, because wet foliage encourages leek rust. For more detail, see how often to water leeks
Leeks have narrow, upright leaves that cast very little shade, so weeds grow easily around them. Hoe between rows, but pull weeds by hand near the plants so you don't nick the stems. A layer of compost mulch around the plants keeps moisture in and slows the weeds down.
Earthing up for longer white stems
As your leeks grow, draw soil up around the stems a little at a time, repeating it several times through summer and autumn. This blanches more of the stem, giving you extra white length. Keep the soil below the point where the leaves fan out, or grit will work its way between the layers. Earthing up also steadies the plants in winter winds.
Growing leeks in containers
Leeks are happiest in the ground, but you can grow them in a large, deep pot of multi-purpose compost. A pot around 40 cm wide holds four or five full-size leeks. Baby leeks are the easiest option in containers. Pots dry out quickly, so they need watering all season. For more detail, see growing leeks in containers
Harvesting leeks
Start lifting leeks while they're still slim, usually from late summer, and you'll spread the harvest over many months. Taking every other leek along a row gives the rest more room to thicken. Ease each one up with a fork rather than pulling, since leeks break easily. Hardy varieties can stay in the ground all winter, and a frost can even sweeten the flavour. For more detail, see when to harvest leeks
Common leek problems
Leeks are mostly trouble-free. The problems you're most likely to see are:
Leek rust: orange spots on the leaves. It looks alarming, but the stems are usually still fine to eat. Choose resistant varieties like 'Oarsman' if you've had it before.
Allium leaf miner and leek moth: their larvae tunnel into the stems. Covering plants with insect-proof mesh keeps both out.
Bolting: a flower stalk shoots up from the centre, usually after a cold spell in spring. Cut it off as soon as you see it, or the middle of the leek turns tough. For why this happens, see why plants bolt
White rot: yellowing leaves and rotting roots. The fungus lives in the soil for years, so move leeks to a new spot.
If your leeks are thin or slow, see why leeks don't grow
Common questions
How long do leeks take to grow?
Full-size leeks take about six months from sowing, so spring-sown leeks are ready from late summer through winter. Baby leeks can be picked after around two months.
How deep should you plant leeks?
Plant them in holes about 15 cm deep, so most of the seedling is below the surface. The buried part becomes the white stem, so deeper planting means more white leek.
Can leeks stay in the ground over winter?
Yes. Hardy winter and late varieties can stand in the ground through frost and snow without protection. Lift them as you need them, right through to spring.
Should you trim leek roots before planting?
Trimming the roots to about 2.5 cm makes the seedlings easier to drop into their holes. Once puddled in, they grow new roots quickly.
Do leeks need a lot of water?
Only while they're young. Once established, leeks in the ground just need a good soak in long dry spells. Leeks in pots need regular watering all season.
Timings, spacing, varieties, pests and diseases based on RHS guidance.