Onions are members of the Allium family and a popular crop for those of us who grow our own food. There are three main groups of onions: salad or spring onions, which are sown in the autumn or spring, the autumn-sown varieties for early bulbs, and the early sown kinds for late keeping.
Alliums are good companions for other plants in the garden. They are usually planted next to roses, carrots, beet, and chamomile to give them protection from disease and pests.
Choose an open site to allow the onions as much sunlight as they can get. Onions do best in light, sandy, well-drained, deep loam, which has been well manured; this should be undertaken in the previous autumn.
The roots need air, as well as moisture therefore waterlogged soil, should be avoided. Dig in plenty of compost and manure at the rate of 1 ½ buckets to the sq. yd. For autumn sowing, do not use manure or compost; sow the seed on land where a well manured crop has recently grown.
Two weeks before sowing or planting out, apply fish manure with 10 percent potash content at 4 oz (120g) to the sq. yd. If you are growing the autumn-sown varieties, a dressing of 4 oz. (120g) of bone meal and 2 oz (60g) of sulphate of potash can be given in February.
If the land has a low lime content add carbonate of lime as a top dressing at 5 oz. (150g) to the sq. yd. best results are gained when the soil is kept at pH 6.5 to 7.0. Yellow-green plants characterize nitrogen deficiency, whilst phosphorous deficiency results in light green plants that mature slowly. Poor bulb formation with brown leaf tips is the result of potassium deficiency.
Two sowings or plantings are essential if you are to have a year-round supply of onions. Onions need to go in as early as possible because a long growing season should allow the bulbs to gain good size to harvest.
Onion sets are small bulbs, which are planted in the spring as an alternative to growing from seed. They have a shorter growing season and many gardeners believe them to be easier to grow and harvest, especially in the north or wetter parts of the country. Another advantage is that they are less likely to be attacked by onion fly.
Sow the seeds in September in rows 9 in. (228mm) apart. This second sowing will be ready to be harvested the following June. Thinning out is done in early spring; those that are pulled up are used in salads. However, it is far better to ensure when sowing that the seeds are sown thinly, this means that there is less likelihood of attack from onion fly.
The lack of rain in mid-summer will mean that Main-crop onions will require watering. In particularly dry conditions they will need to be watered for about an hour every ten days or so. However, water should not be given when the bulbs start to ripen in late summer or early autumn. Thin out where necessary and hoe the soil regularly to keep down weeds.
When the tops are beginning to turn yellow, bend over the necks of the plants; the leaves will gradually dry off; when the skin of the bulbs turn yellow, lift them gently and lay them out in the sun to dry off; turn them occasionally so that they ripen evenly If the weather is poor, complete the ripening-off on shelves in the greenhouse or shed.
After about two weeks they should be ready to put into storage, during this period the flavour will develop. Onions may be stored in boxes but to ensure that air circulates around them, make up a rack of wire netting, two or three-tier high and place this in each box.
Alternatively, their stalks can be tied onto a rope so that they form an elongated bunch.
Start by tying the first by its stalk to the rope with raffia and then continue to tie more around and above working them along the piece of rope or stout twine; these can then be hung around the shed ready for use.