How to Grow Big Leeks

Updated July 19, 2017

Leeks are a versatile member of the onion family. They will withstand the hardest winter and are generally untroubled by pests and disease. They are not the simplest of vegetables to grow, however. They still need fair amount of effort, requiring transplanting and earthing up. Leeks occupy their space in the vegetable patch for a long time, yet they are still an excellent crop for every plot, as the harvesting season is long. Their strong, white roots also able to break up the soil better than any spade.

Choose a sunny piece of land that has been fertilised with manure after the last crop. Ideally, the soil should be well drained, slightly acidic and fertile. Thoroughly dig the soil in winter and leave it rough. About a week before planting, rake the soil to level it off and incorporate a general fertiliser into the surface.

Sow seeds around mid-March, or when the soil is warm enough, in a separate, shallow trench around 1/2 inch deep. Choose a large leek variety and keep the seed moist so it will germinatemore quickly. Cover the seeds with a cloche -- a row cover -- to hasten germination.

Transplant the young leeks when they are about 7 inches tall and as thick as a pencil. If possible, harden off the plants for a week before by removing the cloche during the day. Water the leek bed a day before lifting if the ground is dry. Lift the leeks carefully and trim off the root ends to about 3/4-inch long. Make a 5-inch deep hole with a dibble (a pointed wooden stick made for this purpose), drop in the leek and fill the hole with water to settle the roots rather than filling the hole with soil. Spacing can influence a leek's size, so a gap of approximately 9 inches should encourage larger leeks.

Water well, incorporating a liquid fertiliser to start. Water thoroughly weekly; leeks need moisture and must be well provided, especially if you want larger leeks. Occasional liquid feeding will increase the thickness of the stems.

Gently draw dry soil up around the stems to increase the length of the white stem when the plants are well developed. Do this in stages, drawing a little higher each time. Avoid allowing soil to fall between the leaves. Hoe carefully around the stems to keep weeds down and continue to ensure plants are not short of water.


Earlier varieties are most popular for growing large leeks, as they have more time to reach their maximum size. Choose a giant leek variety to ensure maximum success.


Big leeks are not ideal for culinary purposes, as they lose some of their flavour as their size increases.

Things You'll Need

  • General fertiliser
  • Leek seeds
  • Cloche
  • Garden tools
  • Scissors
  • Dibble
  • General purpose feed
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About the Author

Emma Hall has been writing articles since 2008. She grew up within the market gardening community and spent 10 years in horticulture. She has begun researching more ecological ways of gardening and has work published on websites relating to gardening and travel. She has A-Levels in English and film studies.