Onions

Onions - Allium Cepa

• Onion Cultivation Requirements
• Onion Sowing Types
• Onion Varieties
• When To Plant Onions
• Onion Spacing & Depth
• Care of Onions
• Harvesting Onions
• Common Onion Problems
• Selection & Storage of Onions
• Nutrition & Health
• Preservation
• Onion Hints & Tips
• Onion Recipes

Onion Cultivation Requirements

Soil

Onions do not tolerate acid soil.

Onions sown in the Autumn and those that are to be over-wintered must be grown on well drained ‘warm’ soils. It is best if these crops are grown after a well manured summer vegetable such as Brassicas or Potatoes, and to withold top dressings of fertilizer until growth resumes in the Spring.

Position

A sunny, sheltered spot.

Crop Rotation

Plant onions in the same place as Brassicas were in the previous season.

Onion Sowing Types

There are 2 ways to sow onions, from seed and from sets. Onions Sets are partly grown onions from seed.
Use the table below to weigh up the good and bad points of onion varieties from onion seed and onion sets.

Heat-treated onion sets are easiest to care for and will give you the best chance of success.

Onion Varieties

When To Plant Onions

Onions should be treated differently according to their type. Each is described below.

Maincrop onion seed and sets (small, part grown onion bulbs) should be sown outside starting mid-March. If they are sown under cloche protection, they can be sown four weeks earlier.

Japanese onion seed should be sown outside in mid-August.

Spring (or salad) onion seed should be sown at three week intervals from early April to early June.

Onion Spacing & Depth

Spring onions - 60 per 1m (3ft) row

Onion Sets - rows 25-30cm (10-12 inch). Push the small bulbs into the soil 7.5-10cm (3-4 inch) apart. The tip of the bulb should be just visible.

Care

Check that the onions are receiving a regular supply of rain water - watering may be required in dry periods up until mid-August. From then on, do not provide any water, it may delay the maturing process. Weeding will also be necessary, because onion foliage provides no protection against weeds.

Maincrop onion seeds will need to be thinned (reduce the number of seedlings to avoid crowding) when the seedlings reach about 5 cm (2inch). Thin the seedlings to 13cm (5inch) apart. The same applies to Japanese onions. Maincrop onions from sets and Spring onions should need little or no attention other than water and weeding.

Harvesting Onions

Mature garden onions are ready for harvesting when the green top withers, falls over and starts to turn brown. This usually happens in mid to late summer. Be sure to harvest before the fall rains, mature onions will rot quickly in cool, wet soil.

Lay mature onions in a single layer on newspaper in a warm, well ventilated place to cure for a few days. Leave undisturbed until the outer skin becomes papery and crispy dry. Select unbruised onions, rub off the stringy roots, and braid the tops. Hang in bunches or place in mesh bags and hang away from moisture. If stored in a dry cool place (10-21°C or 50-60°F), they will keep for months.

Onion White Rot

If the foliage is yellow and wilts check for fluffy white growths, this is Onion White Rot. Plants should be thrown away(not composted) and don’t grow garlic or onions in the same area for at least 8 years.

Common Onion Problems

Onion Fly

This looks like a normal fly - it lays its eggs in Spring on the neck of the onion, and the developing larvae will tunnel into the onion and destroy it. Hoe around the onions regularly to expose the eggs. The time of greatest risk is when you thin the onions - the flies are attracted by the scent. Growing from onion sets removes the need for thinning and the onions are unlikely to be attacked.

Onion Eelworm

Eelworms are microscopic worms in the soil which cause the onions to distort and swell in size. There is really no effective chemical cure, and it will be necessary to stop growing onions in the patch of ground for three to four years.

Nutrition & Health

All members of the onion family offer some protection against heart disease. Research suggests that oils in onions (as well as other members of the onion family) help to lower LDL in the blood stream while increasing HDL levels. Mature, dry onions are also a good source of fibre. Only scallions and green onions contain vitamin A.

Preservation

There is no successful way to preserve scallions and green onions for more than a few days. However, mature onions can be dried and hung in mesh bags or braided together and stored in a cool (10-21°C or 50-60°F) place for several months.

The traditional way to preserve onions is to pickle them in vinegar.

Onion Hints & Tips

Why do onions make you cry? When you cut into an onion, the cell walls are damaged releasing a sulfur compound called propanethial-S-oxide which floats into the air. This compound is converted to sulfuric acid when it comes in contact with water which is why it stings your eyes. Chilling inactivates the propanethial-S-oxide so it does not float into the air. Thus, no tears.

To keep eyes dry when chopping onions, try chilling peeled onions in the refrigerator before chopping. To get the onion smell off your hands, rub with lemon juice or vinegar. To freshen onion breath, chew a little parsley or a coffee bean.

Onion Recipes

Have you got any onion recipes? Add a comment below and we’ll add it.

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