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Articles about Vegetable Crops for the Garden

  Advantages of Container Vegetable Gardens
  Best Vegetable Crops for Containers
  Brandywine Tomatoes - Get the Most From This Heirloom Variety
  Choosing a Site For Your Home Vegetable Garden
  Container Vegetable Gardening Tips
  Container Vegetable Gardens
  Double Your Crops
  Getting Children Interested in Growing Vegetables
  Grow Your Own Salad
  Growing Tomatoes in Pots
  Growing Vegetable Plants Becomes More Than Just A Hobby
  How to Grow a Vegetable Garden
  Indoor Container Vegetable Gardening Ideas
  Indoor Vegetable Gardening How to Tips
  Learning About Indoor Container Vegetable Gardening
  List of vegetable crops by difficulty
  Mushroom Growing in Odd Unused Spaces
  Non Hybrid Seeds For Survival Gardening
  Organic Container Gardening - Simple and Easy Ways to Grow Vegetables and Flowers in Pots
  Organic Vegetable Cultivation Table
  Over Wintering Chilli Pepper Plants
  pH preferences of food crops
  Planning your Container Crops
  Planting Tomatoes Upside Down
  Potato Container Garden Tips
  Preparing a Vegetable Garden
  Review: Food4Wealth by Jonathan White
  Vegetable Container Garden Tips
  Vegetable Crops in alphabetical order by name
  Why I Recommend Vegetable Container Gardening
  Why Vegetable Container Gardening is Getting More Popular Today Than Ever
  How to grow organic Asparagus
  How to grow organic Aubergines
  How to grow organic Beetroot
  How to grow organic Broad beans
  How to grow organic Broccoli
  How to grow organic Brussels sprouts
  How to grow organic Cabbage
  How to grow organic Calabrese
  How to grow organic Carrot
  How to grow organic Cauliflower
  How to grow organic Celeriac
  How to grow organic Celery
  How to grow organic Celtuce
  How to grow organic Chinese broccoli
  How to grow organic Chinese cabbage
  How to grow organic Chicory
  How to grow organic Corn
  How to grow organic Cucumbers and Gherkins
  How to grow organic Endive
  How to grow organic Florence fennel
  How to grow organic French beans
  How to grow organic Garlic
  How to grow organic Globe artichokes
  How to grow organic Jerusalem artichokes
  How to grow organic Kale and borecole
  How to grow organic Kohl rabi
  How to grow organic Komatsuna
  How to grow organic Land cress
  How to grow organic Leaf beet
  How to grow organic Leeks
  How to grow organic Lettuce
  How to grow organic Mizuna
  How to grow organic Mustard greens
  How to grow organic New Zealand spinach
  How to grow organic Onions
  How to grow organic Parsnips and Hamburg Parsley
  How to grow organic Peas
  How to grow organic Peppers (hot and sweet)
  How to grow organic Potatoes
  How to grow organic Radishes
  How to grow organic Rocket
  How to grow organic Runner beans
  How to grow organic Salad onions
  How to grow organic Salsify, Scorzonera and Scolymus
  How to grow organic Seakale
  How to grow organic Shallots
  How to grow organic Spinach
  How to grow organic Squash
  How to grow organic Swede
  How to grow organic Texsel greens
  How to grow organic Tomatoes
  How to grow organic Turnips




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Organic Gardening:


How to grow organic Onions


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Onions
Do you know your onions?

Onions

Allium cepa

Family: Liliaceae (Group 6)

Onions are an essential ingredient in many recipes, although it is quite likely that the onions in your local supermarket are in fact shallots, which may taste the same, but grow in groups, instead of singly like the true onion. You can grow both organically. This page only gives cultivation data for onions proper, though. Shallots are dealt with on a separate page.

Onions may be divided into 3 groups: those grown from sets, those grown from seed sown in early Spring, and Autumn-sown varieties. Onions grown for storage must be of spring-sown or spring-planted types.


Site/soil

Onions require good, free draining soil with a high organic content. If you are growing from seed, you need to prepare an onion bed, basically similar to a seedbed in that the soil must be very fine in texture, but with much higher organic content. The soil should be dug over in early winter, incorporating plenty of manure or compost. Leave the ground rough so that the soil may be broken up by the frost. In spring, add lime if necessary and rake the soil flat, firming well. Leave undisturbed for at least 10 days to become 'stale': onion flies are attracted by freshly disturbed soil, but will not lay eggs unless there are onions for their larvae to feed on.

Spring-sown onions

The earlier these are sown, the larger the final crop. Seed should be sown in January indoors at about 50-60ª F (10-16ª C). Either sow in seedtrays and prick out or in modules. Harden off and plant out in March or April.

Ultimate size is determined by the amount of leaf produced by 21 June (Midsummer's day), from which point no more leaf grows, but the bulbs start to swell. Transplants should be kept well weeded so that they receive maximum light and available nutrients.

Spring-planted sets

Sets are immature bulbs. The advantages of growing from sets instead of seed are that they are easier to grow, less prone to disease, more tolerant of poor soil conditions and often escape onion fly attacks. They also mature earlier. The disadvantages are that they are more expensive, there is a smaller choice of cultivars, and they have a greater tendency to bolt. However, the risk of bolting is reduced by selecting smaller sets(!), and by using sets that have been heat-treated.

Autumn-sown seed

Area Sowing time
North   2nd week of August
Midlands/East   3rd week of August
South   4th week of August

Autumn-sown varieties are mainly Japanese cultivars, for harvesting from June to August for immediate use only. Sow seeds 2.5cm (1") apart in 30cm (12") rows. Timing is critical:

In spring, thin seedlings to 5cm (2") apart and give a top dressing of seaweed meal or a foliar feed.*

Autumn-planted sets

Specially selected for their hardiness, they need a well-drained soil to succeed. Plant any time from September to November, 10-15cm (4-6") apart in 30-45cm (12-16") rows.*

* Harvest Autumn-sown and Autumn-planted onions from June to August. Cannot be stored.

Pickling onions (spring-sown)

Special cultivars are available, but it is possible to produce onions of a suitable size for pickling by sowing any of the normal onions (except giant exhibition types), by growing them close together. The competition will keep them small. Either sow 1cm (¼") apart in 30cm (12") rows or broadcast in 24xm (9") bands and leave unthinned.

Recommended varieties

Spring seeds: Ailsa Craig, Bedfordshire Champion, Hygro, Red Baron, Owa
Spring sets: Stuttgarter Giant, Sturon, Balstora, Red Baron, Centurion, Hyduro, Showmaster
Autumn seeds: Express Yellow, Buffalo, Imai Early Yellow, Senshyu Semi-Glove Yellow
Autumn sets: Unwins First Early, Sutton's Early Crop, Shakespeare, Radar
Picklers: Paris Silver Skin, Barletto

Spacing

Sets and transplants should be planted in 22cm (9") rows, each plant 10cm (4") apart, or 15cm each way (6"x6") if equidistant spacing is preferred. Sets can be planted from February to April, though planting of heat treated sets should be delayed until the end of March. Push sets into the ground so that the tip protrudes very slightly and provide protection against birds, e.g. A netting 'cloche'.

Watering is generally unnecessary except in very dry weather once plants are established, and should be avoided after mid July, or maturity and keeping quality may be reduced.

Bulbs can be pulled for use fresh at any stage. They are ready to harvest for storage once the leaves start to die back and the tops bend over naturally. Lift the bulbs and leave them on the surface in the sun for a few days, turning them over occasionally to dry. In bad weather, they can be dried on mats stretched across a frame indoors, in single layers. After 7-21 days, inspect the bulbs, removing all soft bulbs, those with thickened necks, spots or damage for immediate use.

Storage

Autumn-sown seed and autumn planted sets do not produce onions suitable for storage

Store in strings, net bags or on wire trays.

Cultivation table

TypeSpacingSowPlantHarvest
Spring-sown seed15cm x 15cm (6"x6")Indoors Jan-FebMar-AprJuly-Sept
Spring sets - standard-Feb-AprAugust
Spring sets - heat-treated-end Mar-AprAugust
Direct sown (spring)4cm x 30cm (1½"x12")March direct-August
Autumn sown seed:2.5cm x 30cm (1"x12")direct:Thin to 5cm (2") in springJune-Aug
North of UK2nd week Aug
Midlands/East3rd week Aug
South4th week Aug
Autumn sets10-15cm x 30-40cm (4-6"x12-16")-Sept-NovJune-July
PicklersBroadcastMarch directDo not thinAugust

Pests, Diseases and Disorders

The most serious pest is onion fly, particularly on dry soils. The fly is attracted to freshly disturbed soil to lay its eggs. It can be deterred by sowing in a stale seed bed: i.e. a seedbed prepared 10 days in advance of sowing. This is particularly important for August sowings. It is much less likely to attack sets than seed-grown plants. Crops can also be grown under fine nets.

Stem and bulb eelworm can also be serious on infected soils. The best way to deal with this pest is rotation, growing brassicas or lettuces for two or three years. Keep the ground weed-free, as some common weeds harbour these pests.

Downy mildew, neck rot and white rot are the most common diseases. Of these, white rot is the most serious, worst in hot dry summers. Symptoms are yellow, wilting foliage and fluffy white mould on the base of the bulbs, in which round black fruiting bodies appear. Affected plants should be lifted and burnt. No alliums should be grown on infected land for at least 8 years.





Article ©2004 Frann Leach. All rights reserved.

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