How to Plant and Grow Leeks

Leeks are grown for their thick, juicy, long stalks. They are a mild-flavored alternative to the onion. Leeks require a long growing season—up to 170 days. They grow best in cool, mild weather.

Leeks are nearly a year-round garden grower.

Start leeks indoors in winter for planting out in very early spring for an early summer harvest. Set out leeks transplants in late summer for a fall and all-winter harvest.

Leeks are a cool-season crop and produce best if the days remain below 75°F.

Sow leek seeds indoors about 12 weeks before the last frost in spring then transplant them into the garden when they are 8 weeks old—about 4 weeks before the last frost.

Related articles:

If you live in a very warm or hot summer region—the South and Southwest—grow leeks in the cool time of the year: start seeds 8 to 10 weeks before the first expected frost in fall. They will be ready for harvest in late winter and early spring.

Mature leeks can sit in the garden under snow and cold. Just cover them with 12 inches of dry leaves or straw and harvest them when you need them through the winter. Leeks don’t store very well (about a week in the refrigerator), so it’s best to harvest them as you need them.

Leeks are sweeter and more delicately flavored than onions and garlic—cousins of leeks. Serve leeks steamed or braised, chilled in a salad, or a hot leek and potato soup.

Leeks belong to the Allium family which includes onions, shallots, scallions, and garlic. Leeks don’t grow from bulbs like other Alliums, they grow thick, cylindrical white stalks. Above the stalks are fans of flat, blue-green leaves. Both the stalks and leaves are edible.

Leeks can be eaten raw in salads, added to soups or stews, or sautéed as a vegetable side dish. Leeks are most notably used in potato and leek soup, which when chilled is known as vichyssoise. The stalks are the main crop, but the leaves can also be used in soups and stews.

Here’s your complete guide to growing leeks!

Short-season and long-season leeks

Long-season leeks have thick, cylindrical stems. They take about 120 to 170 days to reach harvest. Long-season leeks are usually planted in spring and are harvested from late summer through the winter. Mature leeks are frost-tolerant. They can be stored in the garden through the winter under heavy mulch. They also store well in a root cellar. Long-season varieties include ‘Bandit’, ‘Comanche’, ‘Carentan’, ‘Giant American Flag’, ‘Giant Musselburgh’, and ‘Runner’.
Short-season leeks–also called “early season” leeks–have thin stems and are generally smaller than long-season varieties. They mature in 50 to 120 days. Short-season leeks are commonly planted in spring and are harvested during the summer or early autumn. They are less hardy than long-season leeks. Short-season varieties include ‘King Richard’, ‘Lancelot’, ‘Rally’, and ‘Varna’. Plant short-season leeks where the growing season is short.
Sometimes short- or long-season leek varieties that mature in 90 to 120 days are referred to as “mid-season” leeks.
Choose a variety according to the time of year you want to harvest leeks.

Where to plant leeks

Grow leeks in full sun. Leeks will tolerate partial shade.
Grow leeks in loose, well-composted soil, but be sure the soil is not too rich in nitrogen. Too much nitrogen is good for green leafy growth but can rob flavor from leeks and shallots.
Leeks grow best in well-drained soil rich in organic matter. Add a couple of inches of aged compost or commercial organic planting mix to the planting bed in the spring ahead of planting. Turn the soil to 12 inches deep.
The soft roots of leeks do not like compacted soil. Turn the soil at least 6 to 8 inches deep with a garden fork before setting out transplants. If the soil is heavy clay or filled with pebbles and stones, plant leeks and shallots in raised beds.
A soil pH of 6.0 to 6.8 is best for leeks.
Grow leeks where legumes have recently grown. They will benefit from nitrogen in the soil.
Leeks are often sown or transplanted into trenches. Trench-planting is a way to blanch the stems making them more tender and flavorful.
Prepare trenches 6 to 8 inches (15-20cm) deep and 4 to 6 inches (10-15cm) wide. Seedlings will be transplanted to the bottom of the trench. As plants grow backfill soil around the plants until the trench is eventually filled.
Leeks can be planted in soil-level beds. Mound up surrounding soil or mulch to blanch leeks in soil-level beds.
The stems of leeks also can be blanched by wrapping paper or plastic tubes around the stems.

Leeks planted in garden — Leeks require 120 to 170 days to come to harvest and grow best where the temperature ranges from 55° to 75°F (13-24°C).

When to plant leeks

In mild winter regions, plant leeks in late autumn or winter.
In cool–but not cold–winter regions plant leeks in late summer and autumn for spring harvest. Plant them again in spring for fall or winter harvest.
In cold winter regions plant leeks in the garden three weeks before the last spring frost or later.
Leeks require 120 to 170 days to reach harvest depending on the variety.
Leeks grow best in temperatures between 55° and 75°F (13-24°C). Growth will be slowed by hot weather. Begin sowing leek seeds in the garden no later than mid-spring.
Leek seeds germinate in soil that is 65°F, but the optimal germination temperature is between 70° and 75°F.
Grow leeks from transplants started indoors or from seeds sown directly in the garden.
In mild winter climates, start leeks indoors or direct sow seeds in the garden 12 weeks before the first frost in autumn for harvest in autumn or late winter.
Leeks can tolerate warm temperatures but growth will be slowed.
Mature leeks can tolerate cold and will survive under an insulating blanket of snow.
Plant 12 to 15 leeks per household member.

Starting leeks from seed indoors

If starting from seed, sow seeds indoors 8 to 10 weeks before you want to set seedlings into the garden. Sow seeds in trays filled with seed starting mix. Set seed starting trays under fluorescent shop lights or in a sunny window. Keep the starting mix just moist; do not let it dry out. Seedlings can go into the garden just before the last frost when they are about 4 inches tall.

Starting leeks indoors: Sow leek seeds indoors in early spring; start seeds indoors 8 to 10 weeks before the last expected spring frost.
Start leeks indoors in a sterile, seed-starting mix; use a cell tray of 6-packs. Plant a few seeds per cell. Sow seeds ¼ to ½ inch (12mm) deep.
Seeds will germinate in 10 to 14 days at 70°F (21°C).
Keep seedlings under grow lights for 12 to 16 hours a day until they are transplant size, about 6 inches tall. Gently separate clusters or clumps of seedlings before transplanting.
Transplant leek seedlings into the garden as early as 4 to 5 weeks before the last expected spring frost when they are about 4 to 6 inches (10cm) tall. Transplants should be in the garden no later than early summer for autumn harvest.
To encourage stocky stem growth, keep the tops of seedlings started indoors to 4 inches (10cm) tall until they are transplanted into the garden.

Sowing leeks outdoors

Start leeks indoors up to 12 weeks before the last spring frost.
Sow seeds indoors in a warm, well-lighted location—in a bright window or under grow lights.
Sow seeds ⅛” (3 mm) deep in the seed starting mix.
Firm seeds lightly and keep the soil mix just moist.
Seedlings emerge in 8-16 days at 70°F (21°C).
When seedlings are 2” (5 cm) tall transfer them to individual pots.
Transplant leeks to the garden a week after the last frost or later when seedlings are 6-12” (15-30 cm) tall.
Move seedlings to a sheltered place outdoors to “harden off” 1 week before transplanting.

Mature leeks can tolerate cold and will survive under an insulating blanket of snow.

Planting and spacing leeks

Sow leek seeds ¼ to ½ inch (12mm) deep. Cover the seed lightly with the soil.
Seeds germinate in 10 to 14 days at 70°F (21°C).
Thin or transplant leeks to 4 to 6 inches (10-15cm) apart. Space rows 12 to 16 inches (30-40cm) apart.
Stagger-plant leeks in double rows; this will give fanning leaves more room to grow.
Leeks can be sown or transplanted into trenches 5 to 6 inches (12-15cm) deep. Trench planting allows for back-filling soil around the stems as they grow; this is one method of blanching the stems. (Blanched stems will be white and tender.)
If you transplant a seedling into a trench, continuously backfill the soil to cover all but the top 1 or 2 inches (2.5-5cm) of leaves. Do not backfill soil more than 1 inch at a time; filling in soil too quickly can cause stems to rot. Use a trowel or your hands to gently backfill soil around the stalks.
Trenches are gradually filled in throughout the growing season.
Do not backfill or mound soil over the point where leaves start to branch out from the stems; stay below branching.
An alternative to backfilling soil is to blanch leek stalks by wrapping brown paper or cardboard around the stalks and tying the material in place loosely; this method will also work to blanch the stalks. You can also place plastic or cardboard tubes around the stalks. Slip 6-inch tubes of cardboard (paper towel or toilet paper tubes) or plastic (such as thin-walled, 2-inch, PVC pipe) over the stalks when they are almost an inch thick.
You can also allow watering to naturally collapse the soil around plants filling in the trenches.

Keeping leeks clean—hilling and growing in tubes

To grow large, white, succulent leeks you must blanch the lower part of the stem or shank by hilling the soil up around the stalks as they grow or growing them in biodegradable tubes.

Commercially grown leeks are often gritty because the soil is pushed up around stalks mechanically. Soil and sand can easily slip between the whorls of overlapping leaves low on the plant. Homegrown leeks can be kept clean with a bit of attention and care during the growing season.

Hill up soil or aged compost around the base of growing leeks by hand; simply mound up the soil with your cupped hands. Avoid sprinkling soil over the tops of plants; soil that falls into the space between leaves will be trapped. If you plant leeks in trenches, gently push the soil around the stems and firm it in place as the plant grows. Fill soil around leeks gradually as they develop. Don’t brush the soil on the leafstalks. Rinse away soil when the stalks are lifted.

Growing Musselburgh leeks in plastic tubes

How to grow leeks in tubes

Leeks can be grown, blanched, and kept clean by growing them in tubes—paper tubes or tubes made of biodegradable material (cardboard toilet paper or paper towel tubes will work) or in recyclable plastic tubes such as thin-walled PVC tubing. Tubes will cuff and surround leek stems as they grow; the tubes bock light (and soil) from the stem leaving the shank tender and white at harvest. This is an easy alternative to hilling up leeks.

Place tubes around leeks from the base of the plant at soil level to just below the point where the leaves fork off from the base. You can do this as soon as the plants are well-rooted. Simply gather the leaves and fit them into the tube and then work the tube from the top of the plant down into the soil. Alternatively, you can cut the tube lengthwise and then open it to fit around the stem and then tape the edges together. Stake the tubes for stability and leave them in place until you are ready to harvest.

Container growing leeks

Leeks can be grown in a 6- to 8-inch deep container. Space plants 4 inches apart.
Leeks growing in containers will likely not reach full size.
Grow leeks in a potting mix rich in garden compost. Ask at the garden center for recommended potting soil.
Rather than hilling soil up around each leek plant to blanch the stems, set cardboard or plastic tube around each stalk to exclude sunlight.
Use your finger or a dibber to create holes for transplants.
You can also wrap newspaper or cardboard around the stalks to blanch them.
As young plants grow and the stalks elongate you will need to increase the length of the tube or material surrounding the stalks.

Companion plants for leeks

Plant leeks with carrots, celery, garlic, and onions.
Leeks are often planted near carrots because they repel carrot flies.

Growing leeks

In the garden, space plants 2-4″ (5-10 cm) apart in trenches 5” (13 cm) deep–trenches spaced 6-10” (15-25 cm) apart. Or drop seedlings in holes dibbled about 6” (15 cm) deep leaving just one or two leaves above the soil surface.
As leeks grow, fill in the trench gradually or, if planted on level soil, “hill” them by drawing soil up around the stems.
Large transplants will grow the best leeks.
Grow leeks in full sun to partial shade.
Keep the soil moist during the growing season.
Side-dress the plants with fish emulsion every two weeks.

Watering leeks

Keep the soil around leeks evenly moist; water when the surface becomes just dry.
Leeks need about an inch of water each week. During dry spells, monitor the soil conditions and moisture carefully. Stick your index finger into the soil, if it comes away dry, water the plants.
It is best to water leeks at the base of the plant so as not to splash soil into the crevices between the overlapping leaves. Overhead watering can also leave leek susceptible to fungal disease.

Feeding leeks

Prepare planting beds with well-aged manure and aged compost in advance of planting.
Leeks need a steady supply of nitrogen as they grow to reach full size.
Begin feeding leeks about 4 weeks after sowing seeds and continue feeding each month until harvest.
Fertilize leeks with compost tea, dilute fish emulsion, dilute seaweed extract, cottonseed meal, and other nitrogen fertilizers. An organic balanced fertilizer of 10-5-5 can be used.
Feed plants with compost tea every four weeks during the growing season.

Blanching leeks — Leeks growing in plastic pipes to blanch and extend the stems

Caring for leeks

To grow large, white, succulent leeks, blanch the lower part of the stem by hilling up soil or mulch around stalks to exclude the light as they develop. You can also allow trenches to simply collapse around the stems. Blanching will make the stalks longer and more tender.
Hill up around stalks to just below the leaf junction. Do not add soil higher than the leaf junction; this will help prevent soil and grit from lodging between leaves and stems.
Add 12 inches or more of straw above plants when the weather nears freezing. Leeks must be protected from freezing temperatures.
Mulch between rows and weed regularly, especially early in the season. Weeds compete with leeks for moisture and nutrients.
Leeks can bolt if there is too little soil moisture or too much phosphorus in the soil. A prolonged temperature below 45°F can cause leeks to bolt.

Leeks pests

Onion thrips are tiny yellow-brown insects that suck juices from plants. They may attack leeks in dry weather. Hose thrips off of plants. Onion thrips suck juices from leaves causing the leaves to be silvery or rusty-streaked. Spray plants with water to wash off thrips or spray with neem oil. Beneficial insects such as lacewing larvae and predatory thrips will ear onion thrips.
Onion maggots (the larvae of a fly) can attack leek shanks and roots. Onion maggots are small white larvae that feed at the base of the plant, tunneling into the stalk. Cover plants with floating row cover to prevent flies from laying eggs. Beneficial nematodes will kill onion maggots.
Allium leaf miners are fly-like pests that feed on plant sap and lay eggs on the leaves. They can be controlled with neem oil or by beneficial insects.

Leeks diseases

Leeks can be attacked by fungal diseases rust and downy mildew.
Do not overhead water leeks.
Spray-mist plants with compost tea which is an anti-fungal or get an organic fungicide at the garden center.

Leeks can be harvested as soon as they are big enough to use.

Harvesting leeks

Leeks can be harvested at just about the stage of growth though as a rule, they will be most flavorful when young and tender and about ½ inch round or later when the shanks have grown thick and round.

You can protect leeks from freezing weather by mounding up mulch around them. Leeks can stay in the garden until you need them in the kitchen. But if temperatures threaten to drop below the teens, pull them up and store them in a plastic bag in the refrigerator where they will keep for several weeks.

Harvest leeks as soon as they are big enough to use or wait until they reach mature size. Leeks can be harvested when they are scallion or shallot-size.
Leeks are ready for harvest 75-130 days after seeding, from early autumn to late spring.
Short-season leeks (with thinner stems) can be harvested during the summer.
Long-season leeks (with thick, cylindrical stems) are harvested from late summer through winter.
Harvest when stems reach 1-2” (2.5-5 cm) in diameter and the leaves are 6-8” (15-20 cm) tall—after the trench has been filled in.
Leeks do not store well; harvest as needed. In mild-winter regions, leeks can be left in the ground and lifted as needed.
Leeks will be near their mature size when stems reach 1 to 2 inches (2.5-5cm) in diameter and leaves are 12 to 18 inches (30-45cm) tall.
To encourage full stalk growth, cut off the top half of the leaves about midsummer.
The flavor of leeks is improved after plants are hit by a light frost.
Lift leeks as you need them through winter but complete the harvest before the ground freezes.
Do not wash leeks until you are ready to use them.

Storing leeks

Keep leeks in the garden until you are ready to use them.
Rinse between leaves and stems to remove soil and grit.
Leeks will keep in the refrigerator in a plastic bag for up to one week or in a cold, moist place for 2 to 3 months.
You can keep leeks in moist sand or soil in a cool place–32 to 40–for six to eight weeks.
When freezing weather arrives, leeks can be dug from the garden and stored in a cool–32°F to 40°F–and moist place.
Leeks can be stored upright in a box with the roots set in moistened sand or soil and then stored in a cool cellar.
Leeks can be kept in the garden over winter and survive a hard freeze if heavily mulched. Leeks are biennials; if leeks are left in the garden until spring they are likely to develop seed heads which will compromise the flavor.

Leeks in the kitchen

Leeks can be served raw or cooked. Fresh leeks are milder flavored than onions and shallots.
The topmost leaves are usually tough; discard the tops or add them to a stockpot or something that will be boiling for a long time.
Wash leeks carefully before using to get rid of any dirt that got into the tops; you can cut the leek in half from root to top and then hold it under running water or swish it in a pan of water, pulling the layers apart and rinsing as you go. Then shake dry.
Raw, finely chopped leeks are often added to salads–use in combination or as a substitute for onions, shallots, or chives.
Young leeks can be served like scallions or spring onions.
Leek greens are often used to flavor quiche, broth, stews, and purees.
Steam braise leeks and ser chilled in a salad.
Sautée thinly sliced leeks by cooking them over low heat with thinly sliced mushrooms.
Sauté leeks in butter or add them to soups and stews.
Young leeks can be braised or grilled or chopped and added to salads.
Leeds can be boiled until tender; serve them with melted butter.
Cut the white part of the leek into thin slices and precook by frying before adding it to a soup.
Leeks are rich in vitamins–vitamins K, B6, and C–and minerals including manganese and iron. Leeks also contain flavonoid antioxidants.

How to extend the harvest

Mulch spring-planted, slow-growing leeks with a thick layer of straw in late autumn for harvest through the winter.
Sow slower-growing varieties in summer for an early spring harvest.
Sow fast-growing varieties in winter in a plastic tunnel or cold frame for spring harvest.

Saving leek seeds

Leeks are biennial.
Overwinter leeks in the garden; in the second year they will raise a seed stalk that bees can pollinate.
Leeks are best isolated from other alliums if you intend to save seed and want them to breed true.
Leek seeds are viable for about 3 years.

Leeks frequently asked questions

Q: Are leeks hare to grow?

A: Leeks require a long period to reach maturity, but they are simple to grow. Their culture takes more attention than skill.

Q: Should I start leeks indoors?

A: If you have a short growing season, start leeks indoors. Sow seed indoors 12 weeks before the last frost in spring. Thin sprouts to 1 inch apart. When leeks are pencil thin, transplant them into the garden 4 to 6 inches apart.

Q: Can I grow leeks in a mild winter region?

A: Yes, start leeks outdoors in mid-winter in mild winter regions or plant seeds from late summer to late autumn for harvest the next spring.

Q: How can I blanch leeks?

A: The traditional way to blanch leeks is to set them in a 6-inch furrow and then gradually fill them in to blanch the stalks as the plants grow. This technique requires a lot of work and grit and soil can get into the folds in the stalks. An alternative is to wrap the leeks with brown paper or slip 6-inch tubes of cardboard or plastic (such as thin-walled, 2-inch, PVC pipe) over the stalks when they are almost an inch thick.

Q: Do I have to blanch leeks?

A: No. Leeks will be perfectly useable if you do not blanch the stalks. Blanching makes the stalks whiter and perhaps more succulent.

Q: When should I harvest leeks?

A: Leek varieties vary in maturity dates from 70 to 140 days. Leeks are edible at pencil-thin size or you can wait until they reach maturity when the stalks will be 1 to 2 inches in diameter. Don’t let them flower in the second year; they will be too tough to use in the kitchen.

Leek varieties to grow

There are several varieties of leeks; some come to harvest in as few as 50 days, and others take 140 days to reach full size. As a rule, shorter-days-to-maturity varieties are less cold-hardy. Select longer days to harvest varieties for storing in the garden through the winter. Short-season leeks have a thinner stem and don’t keep as well as cold-hardy long-season varieties.

‘American Flag’ (90-120 days): classic, home garden variety; sweet flavor; 8 to 9 inches long, 1 inch in diameter.
‘Bandit’ (100 days): thick, heavy, winter leeks for late harvest and overwintering.
‘Blue Solaise’: very cold hardy; matures in 105 days.
‘Carentan’ (90 days): green leaves and white shanks.
‘Comanche’ (75 days): long, white shanks; dark-blue leaves; early fall harvest.
‘De Carentan (110 days); long stems; sweet flavor; fine texture; grows rapidly; French variety.
‘Elephant Leek’ (85 days): large stems; vigorous grower; widely grown.
‘Falltime’: tall shanks—thick stems; harvest before hard freeze; 80 to 90 days to harvest.
‘French Summer Kilma (75 days): dark blue-green leaves; long slender stems; European variety.
‘Giant Musselburgh (105 days): Scottish heirloom, best winter hardy.
‘Kilima’: mild flavored; grow to 12 inches tall; 80 to 100 days to harvest.
‘King Richard’ (75 days): grows to full size in summer; not winter hardy.
‘Lancelot’ (70 days): bolt-resistant, virus tolerant.
‘Large American Flag’ (130 days): thick stems; sweet flavor; widely grown.
‘Laura’: very cold hardy; good in very cold winter regions; 115 days to harvest.
‘Lincoln’ (50-100 days): early variety with long, white shanks.
‘Otina’: harvest young or at maturity; very succulent; 120 days to harvest.
‘Poncho’: stocky, short shanks at maturity; 100 days to maturity.
‘Rally’ (85 days): heavy, uniform shanks; rust tolerant.
‘Runner’ (100 days): thick, heavy shanks; blue-green leaves; winter leek.
‘Tardorna’ (100 days): open-pollinated; medium-length shanks; fall-winter harvest.
‘Tivi’ (75 days): long straight shaft; green tops; sweet flavor; Danish variety.
‘Varna’ (60 days): quick-growing summer leek; good for baby leek.

About leeks

The leek is a hardy biennial grown as an annual. It is a mild-flavored member of the onion family.
Leeks have thick white stalks topped with fanning, deed-green, strap-like leaves.
Left in the garden for a second season, leeks will flower and will not be flavorful.
Botanical name: Allium ampeloprasum Porrum Group
Family: Amaryllidaceae (onion family) — other alliums include onions, shallots, and scallions
Origin: Mediterranean, Egypt

Leeks articles on Harvest to Table:

How to Plant and Grow Leeks

Leeks Seed Starting Tips

How to Harvest and Store Leeks

Six Ways to Cook and Serve Leeks

Potato-Leek Soup Simply Made

Garden Planning Books at Amazon:

More how to grow articles:

Learn how to plant, grow, and harvest your favorite vegetables. Click below for all you need to know.

How to Grow Polyantha Primrose – Polyantha Primula

How to Grow Geranium — Pelargonium

How to Grow Larkspur – Consolida

How to Grow Sweet Alyssum – Lobularia

How to Grow and Care for Snapdragons -Antirrhinum

How to Grow Pot Marigolds — Calendula