2004's Late Planting of Onions
20th Apr 2005
It was on the 23 rd April last year that I planted my onions in their beds, and they were probably the strongest plants that I've had for few years. A number of you will probably think that date to be quite late as I know some growers, particularly those growing for the heaviest classes, will have planted during early March. The difference of course is that their beds will have been heated either by having hot water pipes running around and underneath the soil or they will have heating cables just underneath the planting level of the root ball.
Planting later naturally means that the onions need to be in larger pots which is a change from my usual pattern of planting out from a relatively small pot. The reason for the strong plants was certainly as a result of adding Nutrimate to the potting up mixture, the foliage was powerful and standing bolt upright. No heating was given to the bed at all and when it was covered with black and white polythene I was surprised that the bed temperature hardly dropped. If you are concerned about the temperature of your bed being low and you can"t use heating cables in the soil, then cover the bed over with clear polythene. Clear polythene will heat your soil up faster than anything else. At the same time it will also germinate any weed seeds in the soil which you can hoe off prior to laying the black and white polythene. In my case, whether it is the location or not, but my onions always seem to peak around mid July and I find it extremely difficult to keep them growing on after the end of that month.
Last year I had some lovely onions in my bed measuring 21 inches in circumference during the middle of July. They had a lovely green top on them so I thought they would possibly make 22 inches, a size that I like a set of quality onions to be at. It was a mistake, because even though I had about two at that size to harvest at the end of July the remainder seemed to run out of steam and had to be harvested during early August when approaching 21½. There was another problem as well, around half of the onions just wouldn't ripen properly and they never had the superb condition all over that is so necessary when competing at the highest level. The bed was also in need of some organic matter which it has had this time round so I hope to have that little extra bit of growth to give me those extra few inches. The beds have been soaked through a few times to make sure that the level of salts in them is negligible. This is known as the Conductivity reading and if you had a soil test it should be approaching zero on the ADAS scale. If it's a high reading you will need to really flush out the bed with plenty of water as your onions will struggle to grow in soil with a high Conductivity reading.
There's no doubt that the use of the horticultural disinfectant Jet 5 was a real contributory factor to the excellent growth rate that I had in the bed last year. It cleaned out the soil and I never had any problems with any disease whatsoever. The beds were once more given a good and thorough soaking and the way I did it was as follows. I propped a plastic 45 gallon drum on a steel platform that I have and these were on top of my long carrot bed block work, just outside the polytunnel. This means that I had a good head of water that was gravity driven through a length of hosepipe and through my watering lance. Each of the two onion beds as well as the leek beds were given 45 gallons of the diluted Jet 5 at the manufacturers dose rate for cleaning out irrigation pipes. Once the beds had dried out a little they were given 3 ounces of Vitax Q4 and Calcified Seaweed to a square metre and 5 ounces of Nutrimate. The whole bed was then thoroughly rotovated with my lightweight cultivator. The bed will now be raked level and the position of the onions marked out in two rows with eighteen inches between the rows and between each plant. The same size pot that the onions are growing in will then be sunk in the exact location, some slug pellets will be scattered on top and only then will the bed be covered over with the black and white polythene. By simply feeling for the rim of the pot underneath the polythene, you can make a cross cut where the pots are, remove the pot and simply plant the onion in the pre formed hole. Next water each plant with about a pint of water to consolidate the surrounding soil around the onions root ball. Re adjust the split canes and clips making sure that the neck of the onion is perfectly erect. Personally, once I see the onions growing away, in about a fortnight or so, I very carefully remove the clips. With my hand underneath, the leaves, I gently lower those that would fall down and possibly snap off, until they are resting on the polythene.