Preparation of the Onion Beds
22nd Apr 1998
A lot of hard work and preparation went into the onion beds this year, they were initially all forked over to a good depth during early Winter with nothing added at that time in the way of organic matter as the soil was well manured the previous season. The polythene over the roof area was then removed from the Aly traps so the soil within the beds was well and truly cleaned out. During late February the final preparation was carried out and each of the 4 beds were given 3 compost bags full of a mixture of composted oak and Beech leaves.
The soil was sent away for analysis earlier on and the readings on their return showed that the soil was well balanced and needed only two ounces of Nitrogen and one ounce of Sulphate of Potash per square metre to bring the beds up to their optimum nutrient levels. I did however add one extra item and that was 2 ounces of calcified seaweed as a soil conditioner, I have great faith in this product and use it by the bag full every season in all my mixes whether it be for potting on or for the bore holes for long and short carrots, parsnips as well as the long beet and it's excellent also for the lawns.
Soil Warming Cables
Once the fertiliser had been worked into the top spit with my Mantis tiller, the soil warming cables were sunk down about nine inches below the surface of the soil and three lengths run along each bed. These cables are thermostaticaly controlled and don"t cost the earth to run, the thermostat is set on maximum for the first few days and then regulated at 18°C until the warm weather really sets in. Two years ago I invested in lengths of porous piping which are made from re cycled tyres and these were cut into the appropriate lengths and formed to suit the beds giving a row of hoses either side of each row of onion. last year the pipe was just lightly pressed into the top surface of the soil, this time it was sunk approximately 50mm which makes the pipe seep a greater distancs laterally.
The next job was to mark out the beds at 20 inches between the rows and 17 inches between the plants this allows me to fit in 80 plants in the four beds. Once they have been marked out, the same size pot as they were growing in was plunged into the soil up to it's rim and each pot was then filed to the brim with a dilution of Armillatox, the whole beds had already been thoroughly saturated once earlier in the year. This I hope will further help towards cleaning up the small percentage of onions that succumbed to the white rot disease last season.
Finally the beds were covered over with black and white polythene sheeting with the white side upwards and rather than tucking in the edges into the soil using a spade as i have done in the past, the sheet was left to overhang the beds and tacked down with short pieces of batten. This will keep the beds more evenly moist as they had a tendency to dry out along the outer edges last year. Prior to laying down the polythene, slug pellets were scattered over the surface area of the beds just to make sure that the lovely moist warm conditions underneath won"t harbour any slugs or snails.
The onions were moved from the growing cabinet on Wednesday the 10th of March and spaced out on the opposite bench with the artificial lights switched off. This meant that they had no bottom heat or light and were being gradually acclimatised to the conditions that would prevail initially in the polytunnel.
They were planted on Sunday the 22nd which was 5 days later than last year whilst still in their 100 mm square pots and a beautiful warm day it was as well warming up the beds even further. The actual planting after all the preparatory work takes only a couple of hours and as we had a mild night afterwards followed by a few days of rain the plants received no check whatsoever. Even if we now have the odd night of falling temperatures, I'm convinced that if the roots are still kept warm by the soil warming cables, the plants will not suffer any long term effects.
I was more than pleased with the majority of the onions as they were on five to six leaves and measuring in excess of 600mm from the top of the pot to the tip of the leaves. There were however a few plants that had started pulling upwards as if looking for the light and beginning to have too much of a gap for my liking between each leaf resulting in the stem on some of the being well over six inches in length. As I had no spares of the same calibre they were all planted so I"ll just have to see how they perform during the season, I shall certainly keep you in informed.
After planting the split canes and the clips that had supported the onions foliage whilst in the pots were left on this year and will remain around them until the plants are visibly seen to be growing away, at this point they will be removed. Each planting station was then given about half a pint of warm water from the watering butt that I always have in the greenhouse, this ensures that the root ball and the surrounding soil become one ensuring that there won't be any air voids between the plant and the soil and gives the plants every chance to grow away.