He certainly knows his Onions!
24th Dec 1997
There's no doubt that there is some mysterious attraction to growing onions with every good grower having that tag "He certainly knows his onions" and at every top show there is always a group of people around the top exhibitor as he prepares to pull out the onions from his box to stage them. We are however many months away from that enjoyment currently but if we are to be successful next Summer then we must be getting on with sowing the correct strain of seed over the Christmas period.
Onions need a long season to grow to their optimum size as well as getting a sufficient period to ripen up properly so that you have every chance of storing them well into the following new year, sowing right now from seed is therefore essential. Lets first do away with the myth that all large exhibition onions are no good to eat, nothing could be further from the truth, they are mild, tangy and very tasty and furthermore, when grown and harvested properly, they will store well.
Large Exhibition Onions
Traditionally, the large exhibition type onions have been sown on or around Christmas day which gives them plenty of time to grow to an exceptional size so that you can stage them on the showbench during mid August. Alternatively you can leave them to grow on in the bed so that you can have a go during September at the numerous heavy onion competitions. Whichever type of competition you go for it"s important that the onion doesn't have a check to it"s growing pattern at all, particularly during the vulnerable seedling stage. Robert Holland, the past world record holder always maintained that the winning with any exhibition onion could well be settled during the first 6 weeks of growth by maintaining an optimum growth rate.
Before you sow your onion seed, you must decide what materials you are going to use and these must be brought into the greenhouse or conservatory so that they will be warm and ready for sowing the seed. The compost I use will be Levington F2 and this will go into a full sized seed tray so that I have plenty of room to evenly space out the seed on top of the lightly levelled and lightly flattened compost. The tray is then placed inside another tray with no holes in the bottom, this will be half filled with tepid water and within a few minutes the compost will have soaked up the moisture evenly throughout without disturbing the sowing surface. Space the seed out evenly on top, this certainly helps towards preventing overcrowding which can result in you seedlings being drawn and leggy.
When growing your onion plants on in the greenhouse, it's always advisable to have the water at the same temperature as they are growing in, water used directly from the mains will certainly set them back. Always have plenty of water on hand for a days watering and leave it in the greenhouse to warm up overnight.
An alternative compost to use is Levington Multi Purpose or J Arthur Bowers seed and potting compost, you can also make up your own using sieved moss peat to which you incorporate some Chempak seed base fertiliser.
The tendency with most growers is then to cover the seed over with the same fine compost to a depth of about an eighth of an inch. This is fine with most vegetable seed bit the compaction of the peat based compost on top of the seed just as it's germinating can often mean losses. The reason being that as the young seedling is trying to push itself out of the compost, the seed case gets stuck there and very often the seedling dies off. It's much better to cover the seed over to the same depth using fine vermiculite which allows a much more even germination
After levelling off, the vermiculite it's then sprayed with a very fine mist sprayer until thoroughly saturated after which point the compost must have a temperature of about 65°F if germination is going to be quick and even. The tray therefore has to be placed in either a propagating cabinet, a warm conservatory or inside a small electric propagator. I prefer not to cover the seed tray over with glass and newspaper to block out the light in the traditional manner, but rather to spray the compost on a daily basis as and when required with the aim being to keep the compost uniformly moist.
There is no doubt that if you are to have any chance of winning with the heaviest onions, then the young seedlings must be subjected to a sufficient source of artificial lighting to maintain maximum growth. This lighting can be ordinary "Warm" fluorescent tubes or a more professional unit such as the Philips SGR 200 with a SON T Aggro lamp. Initially these lights will be kept on for 24 hours of every day for the first 6 weeks or so after which you can gradually reduce them to 18 hours and after a further 2 weeks to twelve hours (8am until 8pm)
If you just want good sized bulbs for the kitchen, or to show off to your friends then you can do so by having just enough heating to maintain a minimum of 50°F which can be either a mains or bottle gas system with thermostat or even an ordinary blue flame paraffin heater. With the latter, do make sure that it is capable of achieving and maintaining the temperature that you have set, particularly during frosty nights; also the plants are suspect to paraffin fumes, make sure that there is always a small gap in the roof light to allow the harmful gas to escape.
Years ago I used to exhibit onions regularly with a circumference of around 18" and this was achieved easily without any propagators, artificial lights or polytunnels to grow them on in, so you don't have to spend an awful lot of money to grow big onions.
Don't leave the young seedlings too long before you transplant them, I always move them at the crook stage, that is when the tip of the onion with the seed case attached is just about to straighten up from the compost. After removing the young seedling you can then see that there is only one long seedling root developed which allows the plant to be moved on without fear of it collapsing. Do however handle them very gently, you must always remember that the leave is a pipe formation and too much pressure at this young stage will bruise the leaves with the potential for disease spores to enter.
Pot them on individually at this stage and there nothing better or cheaper to use than spent coffee cups from a vending machine (particularly if you know of a source) which are usually 3" in diameter and 2½" deep, pierce a few holes in the base and fill them with the following mixture : 3 parts Levington M2 (or make your own Chempak potting base) 1 part sieved soil (passed through a ½" sieve to maintain a rough textured compost) and 1 part Vermiculite which will have been moistened before hand and kept warm in the greenhouse.
The range of onions available is immense and I list some of them in their various categories:
Large onions for the heavy classes and for exhibition to be sown from now to the end of January - Kelsae, Ailsa Craig Selected, Robinsons Mammoth, Beacon, Lancastrian, Bedfordshire Champion, Unwins Exhibition. All of these are to be sowed the next few days, potted on into 5" pots from which they should be planted under cover from early March onwards. If you have no covers pot on into 7" pots and eventually place them in a cold frame for planting directly outside during late April early May. The alternative is to plant the variety Showmaster which is grown from sets, they should be started off in the greenhouse as soon as you receive them.
The next category is the small onions for kitchen use or onions for the under 8ounce (227g) if you intend to show them. For showing, sow them from the middle to the end of January in a heated greenhouse with a minimum temperature of 55°F, this timing will enable you to have good colour on them by the middle of August. Alternatively, start them off in the same greenhouse from early February or a cold frame from early March, both will be ready for planting out from early March to the end of April respectively, Toughball, Buffalo, Bison, Hygro, Maraton, Reliance, Albion (white skinned), Amigo, Caribo and Juno.
Growing from Sets
The third category can be grown from sets, for exhibition they are best started off in the greenhouse as soon as you receive them from your supplier; pot them up into small pots in Levington M2, once they reach 2" high place them in the cold frame for planting out when fully hardened during April or direct into the soil if growing them in a polytunnel. For kitchen use plant them directly outside as soon as you have them and when the weather and the ground has warmed up sufficiently - Sturon, Centurion, Giant Fen Globe, All Rounder, Balstora, Orion, Jet Set, Stuttgarter Giant, Hyduro, Golden Ball, Red Delicious, Red Supreme, White Prince (white skinned), Jagro, Autumn Gold, Red Baron, Red Epicure.