Medwyn Williams sheds light on leeks and onions!
Maintaining a bright, warm and healthy greenhouse is key to success
Leek bulbils have been pricked out into 60s and 50s cells that fit into a standard seed tray, with a layer of compost in the base from which the emerging roots can gain extra nutrients. I used Humax multipurpose compost, which sustains them until they’re moved on.
They’re grown under 400W SON-T AGRO lights, which are on 14 hours a day to supplement the bleak daylight. I also have a bank of T5 lights covering younger seedlings with a heated mat underneath them.
Last year I grew my best onions and leeks under the Maxibright Horizon 315W CMH Grow Light lamp, which is cheaper to run. At www.medwynsofanglesey.co.uk we sell a Maxibright Digilight Daylight 315W kit with Daylight reflector (V3) and Philips 315W AGRO lamp. Designed for plant growth, it prevents stretching and has very high PAR (photosynthetic active radiation) levels.
Most plants grow well between 400 and 600 PAR and I aim to maintain a PAR of around 400 throughout the growing period. You can increase the PAR by lowering the lamp towards the seedlings or decrease it by raising the lamp above the leaves or flags.
Greenhouse temperature is thermostatically controlled at 15C (59F) to give an even growth pattern. Keeping plants clean and free from pest and diseases is vitally important and I spray every 10 days with SB Plant Invigorator. It’s an environmentally friendly growth stimulant and pesticide and you can eat the crop the same day as spraying.
When potting on leeks and onions, my seedlings go from the cells into 9cm (3½in) pots. In larger pots, over-wet compost roots can rot before they get established. My leeks then go on to 1L, 2L and 4L pots. l You can follow me on Twitter @medwynsofangles.