How to Grow Leeks

Leeks are a cold-weather crop, but there’s no need to pull them when it gets warm out: letting them go to seed allows them to reseed themselves for the fall, plus the pollinators and predatory insects love their flowers. They are really cool looking, too. 

Botanical Information

Taxonomy

  • Allium ampeloprasum

History

  • Leeks originated in the Mediterranean basin and are one of the oldest cultivated vegetables  FV
  • Egyptians used them as currency, along with oxen and beer FV
  • They are an important ingredient in many Asian cuisines, especially kimchi FV
  • Nero, the tyrannical Roman emperor, loved leeks; he believed they’d improve his singing voice; he ate them in soups and prepared in oil; he was called by some Porophagus, the leek eater FV
  • Leeks are included in illustrated carvings and drawings in Egypt and Mesopotamia, dating back to the second millennium BCE SSE
  • the leek is also a national emblem of the Welsh and in Henry V, Shakespeare notes the custom of wearing a leek to identify themselves is an ancient tradition for Welshman SSE

Physical Description

  • hardy biennial

Varieties & Cultivars

Categories or Types of Leeks

Colors Available

Varieties to Grow

Growth Requirements

Climate & Temperature Requirements

Air Temperature

Soil Temperature

Humidity

Day Length or Light Requirements

Site Conditions Favored

Soil Requirements

Soil Texture

  • prefers loamy soil SoC

pH

Nutrient Requirements

  • prefers rich, loamy soil enriched with mature compost SoC

Propagation

Methods of propagation

Seed

  • Timing:
    • Indoors:
      • mid- to late-winter SSE
      • 6-8 weeks before early spring SoC
    • Outdoors:
      • early spring (cool soil) SoC
  • Depth:
    • plant seeds 1/4″ deep SSE
  • Temperature:
    • 55-85°F
  •  Fertilization:
    • fertilize seedlings when 2-3″ tall SSE
  • Spacing:
    • if starting outdoors, space them 1″ apart SSE
  • Germination:
    • 5-7 days SSE
    • 4-12 days SoC
    • 7-14 days SoC

Division

Cuttings

Transplanting or Potting Up

Seed Saving

Planting Out

  • can be planted out 1-2 weeks after all danger of frost has passed SSE

Bed Prep & Soil Amendments

  • make sure the soil is well-fertilized as this crop is a heavy feeder; consider adding compost to the soil the year before you plant SSE

Bed Spacing

  • plant leeks 6″ apart SSE
  • plant leeks 4-8″ apart SoC

Row Spacing

  • 12-24″ apart SSE

Planting Depth

  • plant deep enough so that 1-3″ of the plant are above the soil SSE

Alternative Bed Methods

Container Gardening

Routine Cultivation & Maintenance

Water Requirements

  • keep well-watered through maturity, allowing soil surface to dry between waterings Soc
  • leeks need ample water SoC

Fertilization Recommendations

  • leeks may require regular applications of fertilizer SSE

Mulching & Weeding

  • mulching the soil around leeks can help protect the plant and keep roots cool and moist SSE
  • mulch to conserve soil moisture and control weeds SoC

Blanching

  • as leeks grow, pile soil up around their base to make the white shaft longer; the soil blanches the new growth and it will just grow taller

Pinching or Pruning & Dividing

Support

Winterizing

  • a deep mulch will allow harvest to continue until a hard freeze SoC

Companion Planting

Helpful Companions

Harmful Companions

Companion to..

Pests, Diseases & Problems

Common Pests

Common Diseases

Symptoms

Whole Plant

Leaves

Stem/Trunk

Flowers

Fruit

Roots

Harvesting & Storage

Edible Parts of the Plant

  • the white shaft of the leek, including the light green zone, is primarily what is used in cooking
  • the dark green leaves, while fibrous and inedible when fresh, turn into a fantastic spice when dried and ground to a powder (Here’s the recipe to dry leek greens or tops)

Yield

Days to Harvest / Harvest Timing

Freshly harvested leeks

Freshly harvested leeks

  • Leeks don’t really need to be harvested, unless you live in a very cold area; otherwise, they can just wait in the ground until you need them
  • when pencil thin, they tend to be sweeter than scallions and make a good winter substitute for them FV
  • Aim for harvesting leeks at less than 1″ in diameter (at least for fermenting) FV
  • harvest when stems are thick and succulent, but before bulbing occurs SoC
  • a deep mulch will allow harvest until hard freeze SoC

Harvest Methods

  • harvest whole plants by gently twisting and lifting; in heavy soils you may need to loosen soil with a fork to avoid damaging the stems SoC

Storage of harvest

Fresh

leeks prepared for storage

leeks prepared for storage

  • can be stored in a root cellar
  • Freshly harvested leeks can be kept for at least a week wrapped in a damp paper towel and stored in a plastic bag in the refrigerator.

Canned

Frozen

Freezing leeks seems to be the favored method of preserving them.

  1. Wash & slice leeks – white parts only
  2. Blanch for 2-3 minutes, then put them in very icy ice water
  3. Drain well
  4. Spread onto a sheet pan and freeze until hard (about 30 mins)
  5. Pack into freezer bags (vacuum sealers are a bonus)

To cook from frozen, boil for 8 minutes, or add directly to soups or stews. They won’t brown & crisp nicely if they are wet.

Pickled or Fermented

  • Like other members in the onion tribe, under fermentation the harsh pungency of the raw flavor is mellowed FV
  • Leeks blend nicely with sauerkraut, and like onions, are versatile FV
    • try leeks in the crock with cabbage and root vegetables like carrots, horseradish, turnips, etc
    • consider a leek-wine kraut: prepare a leek-cabbage kraut and finish the fermentation with a splash of wine

Dried

Drying is a great way to preserve your leeks – and to use up the green tops that are too tough to cook and eat; the dark green leaves, while fibrous and inedible when fresh, turn into a fantastic spice when dried and ground to a powder (Here’s the recipe to dry leek greens or tops)

Cooking

Nutritional Benefits & Values

  • 10 g of fructan per leek – this is one of the highest vegetables in fructan (fructan is a fiber and prebiotic for good gut bacteria) WWW
  • When used in fermented recipes, they are believed to reduce the speed of fermentation, allowing more time for the flavor to develop beyond just the acidity FV

Toxicity

Cooking

Preparation

  • trim & discard the roots
  • slice off the dark green leaves, leaving the tight light green, tender leaves (reserve for drying)
  • slice the stalk in half, lengthwise, and rinse under cold running water to remove the grit between each of the leaf layers
  • slice or chop per recipe; most often they are sliced thinly

Cooking Methods

  • fresh eating
  • sauteing or stir-frying
  • baking
  • grilling
  • braising or in soups

Recipes

  • Asian recipes tend to use small leeks, about scallion-size FV
  • slicing thinly, then sauteed in butter is the basis of potato-leek soup or vichyssoise
  • can be used as a substitute for garlic or onions, although they are more fibrous, so they need to be sliced more thinly

Sources:

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