Artificial Lighting and Heating - Leeks and Onions
27th Nov 1996
I have now cleaned out both my greenhouses so that everywhere is spick and span, well at least for a while anyway! The growing cabinet has also been completed and this weekend all the leeks that I started away a few weeks ago will be placed there. They will from this point, right through to planting out time, be given artificial lights for the whole period. This means that they will be growing away for twenty four hours every day of the week.
Not only will growth be steady it will also be accelerated and the plants must therefore be well looked after. As they have some bottom heat at 65° F as well as a regular minimum air temperature of 55°F, you must make sure that the plants don't suffer from lack of water. This can easily happen when you have hundreds of plants growing in such a warm environment, so a daily check must be made of each individual cell or pot and if required each pot or cell is watered individually. I have a small watering can holding a pint or so of water which is perfect for the young plants of both onions and leeks.
Watering is undoubtedly a knack that comes with experience and either too much or too little can check the plants growth, Indeed in the extreme of both cases it can result in the plants going to seed or as in the case of onions, going double. It is therefore well worth spending time going through the plants to check for their moisture content. Whilst carrying out this function, always bear in mind that even though the pot may well appear to moist on top, because of the bottom heat, the compost at the bottom of the pot could well be bone dry, so every now and then take the plant out of the pot for a visual inspection.
The other scenario is that the pot can appear to be dry on the surface and in need of watering, yet perhaps an inch below the surface the compost could be moist, again a visual check will help. I always have a plastic water butt at the far end of both my greenhouses which are regularly topped up with half a capful of Armillatox this is added to a full drum to keep the water clean and free from algae and fungal spores. The plants are therefore always given water at the same temperatures as they are growing in, this means that they don"t have a sudden chill and a check to their growth pattern.
As the leeks are growing away strongly, keep a careful lookout for some of the young plants bowing out at the base. This happens quite regularly with young plants that are growing fast and strong; because the outer leaf is tough, the plant is unable to break it away so it bends over. In severe cases where perhaps you haven't noticed it earlier, the plant can actually bend right over, the answer is to cut through the outer leaf that"s preventing the leek from growing perfectly erect. If you can spot this cultural defect early enough, the plant will quickly sort itself out and grow straight, if it's really bent though I prefer to discard them.
Large Exhibition Onions
Any time now you can be getting on with sowing the large exhibition onions, particularly so if you have your mind on growing them for the heaviest onion classes, but for the quality ones I prefer to wait for until the middle of next month which usually gives me plants that can be planted out towards the middle of April under the polythene covers. Sowing too early means that you will have much larger plants, but of course these plants will be ready for planting in their beds earlier as well. It's important to realise that if sowing earlier, then the conditions at planting out time must be conducive towards the plants growing away unhindered, you may even have to think about heating your tunnel as well as warming up the soil.
Compost and Seed
Make sure that you are ready for sowing, check your propagator as well as your heating system - bring your sowing compost inside the greenhouse now to warm up, I use Levington F1 but Levington's Multi purpose or J Arthur Bowers seed compost will also do the trick - buy your seed now, there's none better for both the quality and for the heaviest classes than Kelsae - clean out your seed trays and pots by washing them in a 100 to 1 dilution of Armillatox.