Outstanding Large Onions
28th Jul 2004
My large onions have grown far better than I ever expected this year as I was under so much pressure with the Chelsea Flower show on the horizon at planting out time. This year though I did go the extra mile in potting the plants on from my normal relatively small pot into a 5 inch one. The condition of the plants at planting out time was undoubtedly the best that I have ever grown. The were strong bold plants with straight powerful necks that looked every bit as if they were going to do the business for me.
Apart from merely potting them on one size bigger than I normally do, the mix was half of Levington M3 and half of Westlands Top soil with a little added Vermiculite to open up the texture slightly. No further nutrients were added apart from some Nutrimate which was given at the potting stage. I had actually forgotten to add this material in when doing the mixing so I added half a teaspoon to every pot when I moved them on. What a difference it seemed to make to the plants, the roots at planting out time were pure white and of such a mass that you couldn't see the compost they were growing in.
In addition to this the three beds that they are growing in were also given 4 ounces to the square yard of Nutrimate but only an ounce of fertiliser by way of Vitax Q4. My reasoning for this was that I have become convinced that, generally, we apply far too much fertilisers to our beds causing more harm than good. All of this rotovated in and then covered with black and white polythene. As it was the first week of May when they were planted I never bothered with soil warming cables as the soil was well warmed up by then.
Another bold move I made was to dispense totally with the watering system that I normally have under the black and white polythene. I do this because I am convinced that the onions don"t want too much water, a damp moist atmosphere is really the last thing that I want around large bulbs that can so easily be prone to Botrytis. This disease will very often come as big disappointment to those growers who perhaps have not experienced it before. To the inexperienced grower they suddenly find a brown soft patch on the onion, usually at just above soil level. Once the patch is there it well spread and quickly devour the onion rendering it useless for any show purpose.
Many years ago I thought I would be a little clever and peel off the infected skins until I got rid of it, it still came back so if I ever have it now, I simply remove the onion to prevent any spores from spreading. Three years ago I had some of the best onions ever and the seeping hoses that I had laid below the polythene were utilised only a couple of times. Indeed the onions were only watered about five times in total. This year is looking similar, they will probably have been watered 6 times up to this week when I hope to start harvesting the best bulbs.
This is a very critical job as you need a set of onions that are as alike as each other as you can possibly get them. The linen tape measure is therefore vitally important and they are measured every day at this time to record their girth. What I hope to achieve is to harvest onions that are all of the same girth and as tall as each other. I have already removed any excess skins taking them down to the last guard skin, this is the skin that I hope to remove after the onions have been harvested so that they all ripen at the same time. This is certainly not easy as the first thing you have to assess before you pull a single onion is, how much growth is there left in them? For instance, if your best onion in the bed is measuring 21 inches around, are the remainder there near enough to make that size in a few days time? An even better question to ask yourself is, can I afford to leave the best onion to grow on to be 22 around and have those left got enough power to motor on to the same size.
Three years ago I took the decision to harvest my best onion at 22½ inches and within a week I had another six lifted, after that they came up at 22 and even 21¾, simply because they had run out of steam. If your onions are ready for lifting, remove the top growth leaving a neck of about 4 inches, then with an old knife, carefully cut away the roots from the base of the onion so you can lift it without any damage. You can then trim away the remainder of the old skins that are inevitable to be present around the root plate.
Remove the last skin, praying that nothing will be wrong with the one left underneath. Wash the bulb in some tepid water with a drop of washing up liquid and dry with a soft towel. Powder the onion with Talcum powder or in my case I use Zinc Starch and Talc which as well as drying out the skin uniformly, it imparts a nice a colour to your onion. I also leave my onions sitting on a bed of fine saw dust which I collect from my local timber merchant and then pass it through a quarter inch sieve to make sure that I have got rid of any sharp bits.