Leeks and Onions
27th Dec 2001
I'm taking a break this week from the series of articles that I have written on various sowings dates for vegetables in different regions of the country to cover some more timely points that need attention this coming week.
The leeks that I started off during early November are now moving away strongly and I have to say that each and every plant in the trays are looking particularly healthy this year.
Condition of Leek Head
There's no doubt that the health of the plant is down to the condition that the leek head was in when the bulbils or pips were harvested from it for pricking out. This year I had the best lot of heads that I have had in years and with the exception of a couple, the bulbils were all removed with a lovely white pearly finish to the prospective root plate. When you have pips or bulbils that are clean and disease free there is hardly a problem with the rooting of them and they just romp away
Mine were started off in Levington F2S which is the normal F2 which is finely graded compost with added sand. I have found this to be superb in setting the bulbils off as any excess watering freely drains away and also allows more air to get in at the emerging root system.
They are now in 3 inch pots and their next move will be into a five inch pot. The compost requirements needs to be adjusted at various stages of potting and the first compost mixture for the 3inch pot was as follows - 3 parts Levington M2, 1 part soil sieved from the leek bed (don't use an eighth of an inch sieve it"s too fine, use a quarter inch or even a half inch sieve as the leek roots likes plenty of rough material in the compost) and 1 part medium grade Vermiculite.
The next potting stage will be a 5 inch square pot and for this compost the soil element is increased so that the leek is gradually being acclimatised to working within a medium containing an increasing amount of soil; trying to emulate the conditions that the leek will eventually be growing in when planted out. The mix is - 4 parts Levington M2, 3 parts of soil, again from the leek bed and sieved coarsely and 1 part vermiculite.
Temperature of Compost
An important consideration is the temperature that your compost is going to be at when you actually carry out the potting. I always like to prepare things ahead of time so that there is hardly a chance of anything going wrong such as the leeks bolting at some future date. The soil at this time of year can be freezing cold even when taken from inside a polytunnel, so it's wise to sieve it at least a day before and leave the bucket or two of it inside the warm greenhouse to acclimatise. This is also true for the Levington M2 bags as well as the Vermiculite.
Collaring and Clips
A question that I often get asked is when is the best time to start collaring and pulling upwards the blanch leeks. Over the past few years I have tended to grow them in their pots without collars for most of the time until the leeks are really large and in 4 litre pots, at this time I will introduce collars. When in the pots I prefer to leave the leek to pull upwards naturally by means of using the plastic plant support clips. These are green plastic clips that hook on to split canes and can form a complete circle to support plant foliage.
In the case of leek plants I use the smallest diameter clip and position it quite high up on the cane so that the foliage is not only supported, the flags are also left tighter together. This means that the centre or heart of the leek is further down the flags and will therefore push upwards in search of light. In so doing it is therefore naturally and slowly extending the barrel of the leek whilst at the same time keeping the barrel green and vigorous.
Checking up on last years diary I found that I didn"t sow my onion seed until this actual date and the resulting onions that I grew were really the best that I have ever grown and staged. Sowing the large exhibition onions too early, by my reckoning, can be a recipe for disaster, it may well be fine if you want to enter the heaviest onion classes where absolute quality is not the key word.
For quality onions the secret is to get the onions growing away well and the tops keeping nice and green until harvest time. This way you will almost certainly harvest onions that will keep for weeks provided that the skin that you harvested the onion on still had a green leaf attached to it.
My first two onions were harvested on the 19th July when they had arrived at 22 and three eighths in circumference. They weighed 5 lb 10 ounces and 5 lb 8 ounces. Another two were harvested on the 22nd when they had also reached the same measurement. This continued until I had lifted my last best onion on the 31st July.
By the time I required the onions for my first show which was on the Bank Holiday Monday in August, I had a good selection to chose from. However in another fortnight I had an even better choice as the later onions to harvest ripened to match the first lot. Such was the quality that I could actually have staged a set of five during early November, all really down to harvesting them on the right skin when they were still actively growing away.