Collars and Supports for Leeks
27th May 1998
The leeks have really got their roots well embedded into the soil now and I can pretty near see them improving by the day, what a difference a week of really warm sunny weather makes. The difference could be seen first during the last week in April and the first week in May when we had a few very warm days and the plants, particularly the Welsh leek could be seen to be pulling themselves out of the first collars that I had on them. I also have another row of the Peter Clark type of leek that up to the first week in May I had not bothered to collar relying on the plant to pull naturally by itself.
Support Clip and Split Cane
This is a method that I first saw being utilised by Ivor Mace and there is a lot to be said for it. Rather than collaring the plants from the very early stages with the barrel or stem of the leek consequently being blanched and turning white, the foliage of the leek is held together well above the button by using one plant support clip which is clipped on to a 75cm split cane. This means that the heart of the leek is in complete darkness which means that it will pull upwards in search of the light whilst at the same time leaving the barrel still green. I believe that this in itself helps to strengthen the plant giving it increased vigour as the whole foliage and barrel are subjected to light giving increased plant activity through photosynthesis.
The leeks were planted deeper in the soil as well this year having had a number last season forming a bulbous base, they were planted at least 5.0cm deep which means that I should have a better chance of getting some parallel barrels on them. This is not because I feel the soil will keep the barrel straight, it's more to do with the fact that the soil area around the developing root plate will have a better chance of remaining uniformly moist throughout the growing season. This means that the plant will be under less stress which I believe is part of the problem that results in the leeks producing a bulbous bottom.
Every leek will now require support in two ways, first by means of a cane behind the plant to which the collars are also attached and secondly by means of the plastic 2.5cm diameter old drainage rods that I have to support the flags. These are suspended from the galvanised tubular hoops of the polytunnel with lightweight chains, a row of pipes either side of the leeks flags or foliage so that the weight of the flags are taken up by the plastic pipes and chains. The pipes should be lifted up in proportion to the growth rate of the plant but do make sure that the actual weight of the foliage is taken up by the supporting structure.
Last year another mistake I made was to lift the pipes too high resulting in the considerable weight of the flags not being taken up by the pipes, this meant a very high percentage of the weight was being taken by the plant itself and this can induce the leek to bend at or near to the bottom. This inevitably happens if the weight of the leek's flags are not evenly distributed on either side of the barrel which can cause the plant to have more weight on one side than the other. This can be a disaster as the leek can never be straightened when it's bent at the very bottom which means that it can not be staged at any worthwhile show.
The two rows that I have of the cleaned up Welsh seedling from Ivor Mace are really looking powerful and are now on 37.5cm collars and will very soon be in need of 45cm collars and they are thicker than a broomstick handle. One word of caution, don't be in too much of a hurry to increase the collars on your leeks if they have not made the necessary growth to go with it. Ideally you want to increase the height of your collars in proportion with the girth of the leek rather than pulling them too fast when they are too thin and incapable of putting on any weight because at the same time they are trying to grow upwards.
The collaring material that I use is builders damp course, this is a very flexible tough black plastic material which you can easily cut to different sizes using a sharp knife and can be bought in a roll at any Builders Merchant and a roll should last you for years.The last collar for me this year will be 52cm which means that with the leek being planted deeper that usual I should be aiming for a length of approximately 60cm. The 30cm collars made from pipe lagging have also by now been removed so that from now on all I need to do is to keep a sharp eye out for pests and diseases.
Thrips and Rust
The main problem is thrips which I can normally control using Polysect and the disease rust will be controlled this year using the ratio of 5ml of washing up liquid to 1 litre of water in a sprayer (do remember to add the washing up liquid after the water otherwise you will be covered in froth and bubbles!). This has worked well for me so far as it leaves a thin sheen on the foliage that acts as a protective barrier which will prevent any spores present from developing on the flags and getting really out of control.