Large Kelsae Onions
16th Jan 2003
My own re selected seed of the large Kelsae onions are doing very well at the moment and will very shortly be ready for transplanting. We were away from home for two weeks over the Christmas and New Year period so the onions were sown a week or so before we left. They were sown in Levington F2S compost which has added sand and the germination must have been quick for them to be ready now.
Over the years I have tried many different ways of pricking out, in the early days I used to prick them out directly into seed trays or into small pots. For the past few years however they have been transplanted into multi cells 40, that is 40 cells of thin disposable plastic that fits into a full sized seed tray. These served me well as the plants very quickly established a strong root system and in no time they were ready for potting on. Two years ago though I tried a new system simply because space was limited under my growing lights. They were 60 cells in a tray and I am convinced that young seedlings prefer this smaller cell unit as the roots hit the side and bottom faster resulting in a stronger and more upright plant.
They will however need potting on slightly earlier than if they were in their 40 cells. The compost that I use for the pricking out in the 60s cells is Levington F2S, it's fine and easily slips into the holes. Once you have loosely filled a tray, tap it down on the bench a couple of times to make sure that there are no empty voids in any cell. Another good tip is to bring your bag of compost into the warm greenhouse a couple of days before you intend to use it so that the compost and the young seedlings are all at the same temperature.
If youv"e have had a good germination and the plants are all even, the black empty seed case of the onion should still be attached to the tip of the seedling leaf. The longer you can manage to keep this attached is a sure sign that the plants needs are adequately catered for in every way. Too much or too little water, not enough heat, poor compost, one or all of these things would have made the seedling die back and loose the seed case. I have actually had a seedling leaf attached to some of my plants right up to the final potting up stage.
Use a piece of thin cane or an old fork from the house to go right underneath the seedlings in the tray and bring up a small cluster of them. Tease one seedling at a time from the cluster and, always holding them gently by the leaf, insert each one into a preformed hole in the compost. For this I have made myself a little tool from a split cane which has been sharpened down to a point at one end and is very useful to get the young roots inside the hole.
Over the years I have heard a lot of talk about the relevance of the length of the young seedling root to the eventual size of your onion. In my mind that is a load of nonsense as I have proved over the years. For convenience sake, I actually nip off with my finger and thumb the majority of the root, leaving just under an inch or so. This then makes it very easy to plant them and I haven't noticed one bit of difference in my onions. Indeed two years ago I had, without any doubt, the best onions that I have ever grown, so there lies the answer. Plant the seedlings so that the potential root plate will be approximately a quarter of an inch below he surface of the compost, also select seedlings that match each other in size and leave the weaker ones alone.
Once you have filled up a whole tray of 60 give them a good watering, I will use water from my plastic water butt which is permanently in the greenhouse which means that the water and plant temperature are the same. The drum was thoroughly scrubbed clean using Armillatox during early December and then filled with clean water with about a desert spoon full of Armillatox added to it. This keeps the water fresh and clean as well as keeping the green algae clear from the top of the peat based compost.
The trays are then placed in my growing cabinet with artificial lights overhead which at this point in time will be left on for a period of 16 hours per day. For many years I used to have them on for 24 hours, right through to mid February and then gradually reduced down to 12. However, after noticing the quality of the plants that I have grown at the University greenhouses at Bangor, where the lights are always controlled at 16 hours, I decided to change with no adverse effect at all on the plants. They will also have some bottom heat on to really give the roots a kick start and this will be left at 70°F.
Judicious use of Water
One of the main elements to good growth from now on will be the judicious use of water, too little or too much will kill them so you have to be quite regimented at this stage. Make sure that each and every cell within the seed tray of 60 has an adequate amount of water on a routine daily basis. I like to check mine twice a day, first thing in the morning as well as last thing in the evening. My best advice is, never use a large watering can, it doesn"t matter how good the rose is it will always give too much water all at once and usually to where you don't want it. I always use a small 1 litre can (picture attached) with a small orifice so that I can direct the water only to the cells that require it. Yes it is tedious and boring but has to be done if you are to get good onion sat the end. Indeed I would go as far as to say that the first six weeks of growth in the young seedling onions sets your stall out for then year. If you get nice healthy strong seedlings then you are well on your way towards a winning set of quality large exhibition onions.