Growing Heavy Onions + Blanch Leeks
7th Dec 2000
For those of of you who have aspirations of growing a really heavy onion with a view of having some fum when entering it in a heaviest onion competition next year, you should be thinking about sowing some seed right now. You must though make sure that you have the correct sort of seed to start with, the saying 'you cant make a silk purse from a sows ear' is perfectly true in this context. The seed has to have the in built capacity to grow to a large size, after that it depends exactly on how you grow it and how well you look after it. If you have trouble getting the right type of seed, then I have some in my seed catalogue which is reselcted from the same line of onion that still holds the world record at 15lbs 15½ ounces. If you are interested in getting a catolgue, drop me a line together with 3 first class stamps to Medwyns, Llanor, Old School Lane, Llanfairpwll Anglesy LL61 5RZ.
Do remember when sowing the seed that at this time of year it is necessary to have some heat to help the seed germinate. This heat can be in the form of a propagator or the greenhouse may well be heated itself. A propagator with a thermostat is the best and fresh onion seed will usually germinate in under two weeks. Use the best quality seed compost, I prefer to use the Proffesional range of Levington composts starting with some F2 with added sand and then progressing to a stronger mix as the seedlings develop.
Another simple but important task is to make sure that the seed tray you use is clean, it only takes a few minutes to wash them and I just leave mine soak for a while in a dilution of Armillatox in an old galvanised bath that I have at the bottom of the garden. Sow the seed sparingly on top of the compost making sure that eevery seed has it's own space, this will result in a stronger and more even seedling development. Cover the seed over with the same fine compost or use some fine vermiculite which I have used for the past few years with great results. Water the compot over with a fine spary and place the tray in the propagator, I never cover the seed tray with glass or anything else but I check the surface of the compost daily and give a fine spray of water should it appear to be drying out.
My blanch leeks have been growing away now for over five weeks and it's amazing how fast they develop from bulbils given the ideal conditions to grow under. This year, for the first time, I took nearly all of the trays of rooted bulbils over to the University College greenhouse at Bangor where I grow all my vegetables for ther Chelsea flower show. The facilities there are superb with constant artifiacial lighting set for16 hours every day as well as having three different temerature regimes in the three attached houses.
Last year I experimented with striking some of the very poorest looking bulbils, some were very tiny and weak, and they were left to grow or die in the warmest house which has a steady 75°F. The results were amazing, after a month, every one had rooted and were as big as some of the others in my own greenhouse that were initially stronger but also had been rooted earlier. The plants are now looking well and as I do not want them to get too drawn they will be transferred this weekend back to my own garden and into the propagating area. The growing area is 12 ft long and 3 foot wide and is totally enclosed with hardboard and reflective polystyrene material; this gives good light all round the bed from two SGR 200 lamps.
I have two types of blanch leeks growing, the PC leek and the Welsh seedling, and those that I shall be growing on for my own use will be potted up into 3 inch pots any day now. I seem to be able to grow the Welsh seedling much better than the PC type so I shall end up growing around 32 of these and ten to a dozen of the PC. The first batch that I shall pot on will be double the quantity that I need this allows for a much more even selection when I come to pot them up again and any weak ones will be left behind.
The mixture that I shall use for the initial potting will be the same one as I use for potting on the onions and is a follows:- 3 parts of Levington M2, 1 part soil that I have already sieved from my onion bed and stored in bags in my potting shed, and 1 part Vermiculite. I was informed by a representative of Levingtons that should any of you have problems getting hold of the M2 compost, it's exactly the same product that's in the amateur Levington Multi Purpose bag.