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How to Grow a Giant Leek

This is a picture of our 6.4kg 2011 leek Just over 14lb.  Read below for a guide on how to grow the leeks.  Leeks are available to purchase from our shop

How to Grow a Giant Leek

We have been producing our own leek seedlings for many years.  Our largest leek was exhibited at the Shepton Mallet Giant Vegetable Show and weighed just over 14 pounds.

Below is pictorial information on how a leek seedling/pip is produced.


Around the end of October, beginning of November, using a standard seed tray filled with multi-purpose compost, place the leek pips into the individual modules.  The pip will need to be on a heated sand bench to propagate and they will take around 7 days to root.  The purpose of individual modules is to ensure that there is minimum disruption to the root system when they are transplanted.


Allow them to continue to grow on but once they have produced their third leaf they will benefit from being potted on again into a larger pot.

Around late November, select the strongest plants and pot on into 3” pots filled with multi-purpose compost and slow release fertiliser (Scotts Osmocote).  At this time, also cover the roots with mycorrizhal funghi.  We ensure that the plants have a minimum of 13 hours lighting during their early stages.  This will include some form of artificial lighting.

First you will need to choose a site that has good drainage. If you do not possess such a spot then you can improve the soil structure by adding plenty of organic matter to it.  In soils where even this will make little difference then you will need to consider planting your young giant leek plants into a mounded or raised bed. A number of growers, such as Joe Atherton from Mansfield, have raised beds in large greenhouses

Our leeks are planted outside into purpose made leek beds, but prior to planting into the Keder Greenhouse, they are hardened off for two weeks.

Leeks have a hearty appetite.  The soil is top dressed with bonemeal and well-rotted manure in the autumn of each year.  Prior to planting, work the top of the bed into a fine tilth and add around 55grams of Superphosphates, 28 grams of hydrated lime or 500grams of calcified seaweed to every 3 square yards.

When the plants are initially establishing themselves in the ground, we use a balanced liquid fertiliser once a week and Shropshire Seaweed once a fortnight. We have used Chempak 2 until august and then switch to Chempak 8 until the shows. Please don't rely on the nutrients from multi-purpose compost and well-rotted manure as the leeks have a long growing season, keep feeding them at least once a week.  Don't overdo it as leeks are susceptible to bolting.  We have grown a number of leeks on the allotment this year for the kitchen garden and they have not been fed once.  They grew to around 4 to 5 pounds

In addition to feed, the leeks need support during the growing period and we have made a frame that fits either side of the leaves to support the leaves.  This is essential as the leaves are susceptible to splitting through he middles if they are not supported

Keep an eye out for the dreaded leek moth and make sure that you cover with enviromesh or equivalent to prevent pests from destroying the leeks.  Never water over the top of the leeks.  If water gets inside the foliage, this is likely to cause the leeks to rot!