How to grow winter onions
The first thing to think about when considering winter onions is whether or not they are the right crop for you. The benefits of growing these vegetables are numerous; planting sets in the autumn allows them to get a head start before winter settles in. The sets are less prone to drought that causes onions to bolt and you will have a crop weeks ahead of your peers. Weeds grow slowly during winter, so there is less competition for resources such as food and water, so winter onions will be much larger than main-crop ones. In addition, they are extremely easy to grow, so who wouldn’t want a vegetable like this. Taste-wise, they are every bit as flavourful as main-crop onions.
know your onions
First source onion sets from a reputable grower, that way you will have a crop that is free from disease and deformity. Two good winter onion varieties are Senshyu, a Japanese variety, golden-skinned and globe-shaped, and Radar a good white onion.
October is the best time to plant winter onions, but before planting your sets it’s important to prepare the soil. Dig the ground over with a garden fork, and work in some well-rotted homemade compost, or failing that, some well-rotted manure. Rake the ground level and make a shallow drill.
Onion sets should be planted in rows with around six inches between each set and eight to ten inches between each row. The sets should be put in root end downwards and should have their shoulders and tip above the soil. However, blackbirds and jackdaws may take great delight in pulling your onions up to look for grubs. If that happens it’s quite ok to plant the entire set just under the soil.
If the autumn is dry and warm it’s best to water your onions twice a week for the first two weeks, to ensure they don’t dry out too much, other than that, no watering is required.
Feed the onions with an organic manure, such as pelletted chicken manure once between autumn and Christmas, and then once a month throughout the growing season the next year.
Although weeds will be growing slowly it’s still important to keep winter onions well weeded, particularly as spring begins, and this is where a sharp hoe comes in useful. When planting it’s a good idea to leave enough room between each set, so that the hoe can get through, otherwise you’ll end up hand-weeding.
By early summer, winter onions will be huge, some up to 2lbs in weight, whilst main-crop onions will be just getting going, and will probably be wanting to bolt if the weather is dry.
Onions are ready for harvesting when the tops go brown and die back, however, you can pull them early. If the chef needs onions for supper, dig a few up whilst still green; this seems to make no difference to the flavour at all.
It’s best to harvest onions when the weather is dry and settled. Lift them with a garden-fork and leave them lying on the soil for a few days to dry out. Have a contingency drying out area such as a child’s bedroom, the airing cupboard or under your partner’s side of the bed in case the weather turns foul.
Many growers say that winter onions don’t store well, they do, but they must be scrupulously dry first, so after a few days drying twist off the brown tops and rub off any loose skin and soil, then leave them to dry for a few more days. Place the onions on newspaper in a tray and store somewhere cool and dry, such as a garage or well-insulates shed, then use them as needed.
By growing winter onions as well as main-crops, it’s possible to grow enough to use all year round.