How to grow onions

This versatile veggie always tastes better when it has matured in your own organic vegetable patch. Getting to grips with growing onions will mean lavishing some old-fashioned TLC on your crop but we'll show you the ropes in this easy-to-follow guide. Of course, if you want to talk to your onions as well, that's entirely up to you…
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Preparing to plant onions
The cook's friend
No kitchen garden is complete without onions. And most onions, including white-skinned, golden and red varieties, are within the scope of a novice home-grower. Usually, onions are planted in the spring for harvesting in the summer and autumn but there are varieties that can be planted in late summer for an early crop the following year (see Lesson 5). Stored properly, home-grown onions will enrich your cooking long into winter.
Open location
Onions need sunshine to ensure that they ripen properly, so pick a sunny, open position. Well-drained, fertile soil that has been allowed to settle will give your onions the best chance. Ideally, you should dig over the ground during the winter, working in plenty of compost. Some gardeners like to enrich the soil with general purpose organic fertilizer around 10 days ahead of the planting date. Avoid acidic soil.
Taking the plunge
If you haven't had a chance to dig the ground over in winter, don't despair. As long as the soil is reasonably fertile, go ahead and get some onions in. Growing vegetables is all about giving things a try and onions are generally pretty forgiving. But don't be tempted to add manure to the plot as a last-ditch effort to enrich the soil. Recently added manure attracts underground slugs and you won't want those beasties anywhere near your onions.
Try these
Among the straw-coloured onions for spring planting, Balaton, Bedfordshire Champion, Centurion and Orion are all worth trying. Red Baron is a cracking red-skinned variety. Late onions include Reliance and Express Yellow. White Lisbon is a proven spring onion variety. -

Planting onions
Only the crumbliest
Aim to get your onions in the ground in late March or April. Shortly before planting, you'll need to prepare the ground by raking it thoroughly. Break up all clods of earth until you have a fine, crumbly soil known as a "tilth". Remove any stones that you missed during winter digging and clear the patch of all weeds: young onion plants are vulnerable to greedy competitors. Firm the soil after raking.
All set
The easiest way for beginners to get going with onions is to plant sets rather than seeds. Sets are miniature onion bulbs that have been especially raised for planting. Some varieties have been heat-treated to prevent bolting (going to seed). Plant the sets in holes so that just the tip of the bulb peeps through the surface. Firm well after planting. Space the sets between 5cm and 10cm apart, depending how large you want the mature bulbs to grow. The rows should be 25cm to 30cm apart.
Sowing seeds
Create a 2cm-deep drill (trench) with a hoe or trowel. If the soil is dry, water the drill. Sow the seeds thinly and cover them gently with soil. Space the rows 25cm to 30cm apart. The seedlings should begin to show after a few weeks. Keep an eye on your drills after sowing. Don't allow the soil surface to become dry and hard. Onion seedlings are fragile young plants and find it difficult to break through a hard surface. -

Caring for onions
The wrong scent
Once the seedlings have straightened and grown to around 5cm, thin them out, leaving gaps of 5cm to 10cm, depending on the size of bulbs you're aiming for. Don't bruise or over-handle the thinnings and dispose of them immediately: their scent can attract pests. Obviously, this is one chore you won't have to do if you grow your onions from sets.
Rubbing out rivals
Whatever your onion-growing method, one task cannot be avoided. You must weed diligently. Because the foliage of onion plants grows vertically, there is no shade to discourage weeds. Left unattended, weeds will rapidly colonise an onion bed. It is fertile ground, after all. Seedlings in particular need your help to make sure they're getting all the nutrients that the earth has to offer. Weeds are no more than gatecrashers at the soil party. Chuck 'em out! Young onion plants should be watered during dry spells.
Young upstarts
Spring onions, also known as salad onions or scallions, are a great addition to a summer table. Growing these fresh, tangy veggies is lots of fun. Sow as for normal onion seeds in drills 15cm apart but leave out the thinning process. You'll soon have a row of young scallions that will be ready for eating in around eight weeks. Pull alternate plants before the bulbs begin to swell. If the soil is dry and your spring onions are reluctant to leave the earth, try watering the row before harvesting them. -

Onion problems
Approaching maturity
As the summer continues, you need to keep up your weeding routine to give the onions the best chance of maturing. Water during very dry spells until mid-August. After this point, there's no need to water the plants, which are now entering the final stage of the maturing process.
Tunnel trouble
Many gardeners raise trouble-free onions but you may encounter one or two problems. Onion flies, which look similar to common house flies, lay their eggs around the bases of young onion plants in late spring. When they hatch, the larvae make for the nearest source of food – your onions. They tunnel into bulbs and destroy plants, turning the leaves yellow. If you spot an infested plant, lift it immediately and destroy it. Onion flies are attracted to the smell of thinnings, so planting sets cuts down the risk of infestation. They are also attracted to the smell of manure – another reason for not planting onions in soil that has been recently manured.
Purple problem
Wet summers may encourage an attack of downy mildew. The leaves become covered with grey patches which deepen to purple. Remove and destroy infected plants. Thin sowing and early thinning lowers the chance of downy mildew striking, as does the use of sets rather than seeds. Generally, it pays to rotate your onions around the garden so that infection or infestation from a previous year cannot come back to haunt the new crop. -

Harvesting & storing onions
Sunshine harvest
Once the leaves have yellowed and toppled over, leave the bulbs in the ground for another fortnight. If possible, harvest your onions on a sunny day. Lift them gently with a fork and lie them in the sun to dry out. If the weather isn't cooperating, dry your onions under cover, somewhere dry and light. The drying process will take at least a couple of weeks, depending on conditions. When the skins are dry and papery, rub off the soil and prepare them for storage.
Good keepers
Only store sound onions. Damaged or thick-necked bulbs should be used or rejected. Trim the foliage and store in boxes or nets in a cool, frost-free location. Alternatively, you can leave the foliage on the bulbs and plait them on to a length of stout string. Some varieties are specifically bred for their storage qualities and will keep for up to six months.
Winter sleepers
Slow-growing varieties, often known as Japanese onions, can be sown in late summer or early autumn to provide a useful crop 10 months later. Prepare the ground and sow seeds as you would for a spring planting. Do not thin the seedlings: simply leave them in the ground over winter. When growth begins again in early spring, thin the young plants and feed with a general purpose organic fertilizer. Three months later, you'll have fresh onions to kick-start your summer bounty.











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