Medwyn Williams gives watering tips for onions
Grow your onions on in small cells and water sparingly for better success
If there’s a secret to growing onions, as often some growers seem to think there is, it’s in the watering regime, which is also the most difficult aspect of growing to teach anyone! My preference has always been the same, if I’m in doubt regarding the watering I leave them alone until I know they’re drying out. Applying the correct amount of water in the correct way throughout the growing cycle of onions is really important.
When the seedlings are ready to be transplanted from the seed tray they should first go into a small cell and not a big pot, it’s much too large for them initially. My father had a saying that used to tickle me: “You’d never put a baby into a double bed would you, he’d be lost in it!”
I always use the smaller cells made up of 40, 50 or 60 in an unit that fits into a normal-sized seed tray and using Levington F2S as a first growing medium, they soon romp away. Using these smaller cells means the roots hit the side and bottom of the cell much quicker and they seem to stand upright much faster. You also have less mass in each cell so that even if you overwater it soon dries out. When they’re in these cells you need to water sparingly using a small watering can and applying the water as and when each cell is drying out. Remember that roots need to have some air around them and if they’re sopping wet it’s never going to happen.
I had a customer who came to me earlier on in the year with some onions that had been given everything they wanted in terms of growing, but the choice of pot was completely wrong. The young seedlings had been transplanted into 10cm (4in) pots and were struggling to grow on because the pot was far too large. The mass of compost around the roots was more likely to be consistently wet as there was a larger volume of it to dry out. They should have been moved into a smaller cell and then transplanted from there into a 9cm (3½in) pot after they’d developed a good root system.