How to produce bulbils

I am often asked what is the best way forward when your leek bulbils or pips or grass that develop on the leek heads are ready too early. In other words the heads for instance could be fully grown by now and are often bursting open as the bulbils develop, with many falling on to the ground. If you were to prick them out right now the probability is that the resulting leeks next year would bolt or go to seed prematurely. The answer therefore is to grow them on as cool as possible to hold back the growth

19^th September 2007 How to produce bulbils

I am often asked what is the best way forward when your leek bulbils or pips or grass that develop on the leek heads are ready too early.  In other words the heads for instance could be fully grown by now and are often bursting open as the bulbils develop, with many falling on to the ground. If you were to prick them out right now the probability is that the resulting leeks next year would bolt or go to seed prematurely. The answer therefore is to grow them on as cool as possible to hold back the growth.

So, what am I talking about then when I refer to pips bulbils and grass.  The three names refer to a method of growing leeks which in essence is akin to growing them from a cutting, they are part and parcel of the mother plant and will therefore carry exactly the same characteristics. You have to remember that all leeks for exhibition are usually grown in this manner and are rarely grown from seed. There are now though a couple of new F1 hybrid varieties now such as Snowdon and Windermere that come quite close to those from bulbils.

So how do we go about creating these little plants that develop on the seed head?.  The first thing is find a good stock of the leek that you intend to work with.  Starting right now, you can select one or two of the best leeks that you have grown this year, be they blanch, Intermediate or Pot. Make sure that they are free from any viruses, diseases and are of the correct form for that variety with no visible bulbous base.

You can cut through the barrel about 6 inches above the root plate and this is the stump that will produce these bulbils next year. Remove with a sharp knife all of this years roots as well as the layers of flags which form the barrel until the barrel diameter is reduced to the same diameter as the root plate.  The reason I do this is because when removing the flags you are exposing a bare area just above the root plate from where more roots will eventually develop after the leek stump is planted.

I like to pot them up individually in 4 litre deep pots with the root plate about two inches below the surface of the compost.  Use the best compost and the one that I use will be Humax Multi Purpose N02 which contains some soil.  Leave the leek outside now to root and only bring it under cover if there is a frost warning.  The idea is to grow the plant on slowly rather than having a quick growing plant that will develop it’s flowering head too early.

Next Spring the leek will push up a seed head and this will eventually open into a flower head when it’s about four feet tall. Make sure you have a strong cane to support each leek with the top of the cane ending just below the developing head.  Before the flowers open, remove them all from the head using a sharp knife or scissors. You will then be left with the heart of the plant, completely shaved off of all flowers and no bigger than you thumb nail.  Within a matter of days you will see the young green bulbils starting to grow on the head.

Within a few weeks they will be shooting upwards and look like a tuft of grass, which is where the term ‘Grass’ came from when referring in particular to Pot Leeks. Leave them growing as cool as possible and only start to prick them out from the first week in October to ensure bolt free plants.

Regards

Medwyn