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Growing vegetables
Onions

This is a very rough guide to growing Onions (seeds, sets and Spring Onions) in the UK, but even within the UK, the climate varies, so due allowance must be made for local conditions.

As well as variations in climate, there are also numerous different named varieties of the different vegetables - always read the seed packet for detailed guidance for particular varieties.

When sowing seeds, always mark the line of seeds to show the position and label the rows so that when the seedlings come up, you know what they are.


Terms used below:

Drill - a shallow depression into the bottom of which seed is sown - normally formed by pulling a hoe or a gardening trowel (backwards) through the surface of a prepared bed. Drills are used where the planting depth is relatively shallow and seeds are planted close together. Once the seeds have been sown, they are covered by pulling a hoe over the surface of the bed to fill the drills.

Seed bed - a specific area of the garden where seeds are sown for germination and later the seedlings are 'planted out' to other areas. The area is normally level and with a fine soil, this helps the young plants to grow and makes it easy to lift the plants for planting out.


Onions (from seed)

Where to sow Outdoors in a open ground

 

Site/Soil Open, rich, well drained, well dug. Lime if acid. Preferably manured previous Autumn, do not plant or sow on freshly manured bed.

Avoid planting in an area where the previous crop was of the onion family.

 

Sowing time Spring sowing: February under cloches or March to April

Autumn sowing: August (not advisable in cold areas)

 

How to sow and aftercare Sow onion seeds in the Spring or Autumn very thinly in 1.2cm (½ inch) deep drills, leaving about 25 to 30 cm (10 to 12 inches) between rows.

Thin Spring sown onion seedlings in stages to about 5 to 10 cm (2 to 4 inches) - make sure all thinnings are removed (they may be used as spring onions) to prevent Onion Fly attack.

Thin Autumn sown onion seedlings to about 2.5cm (1 inch) in the autumn - make sure all thinnings are removed (they may be used as spring onions) to prevent Onion Fly attack. Further thin the onion seedlings to about 5 to 10 cm (2 to 4 inches) between plants in the Spring.

(Close spacing will give smaller onions than wider spacings)

Onions must be thoroughly dried before storage, if the weather is fine, the onions may be laid on the surface of the soil to dry naturally - otherwise spread them out under cover to air dry. When dry, cut off the dead leaves before storing.

 

Time from sowing to harvest About 22 weeks (depends on variety)
   
 

Onions (from sets)

Where to plant

Outdoors in open ground
Site/Soil Open, rich, well drained, well dug. Lime if acid. Preferably manured previous Autumn, do not plant or sow on freshly manured bed.

Avoid planting in an area where the previous crop was of the onion family.

 

Sowing time

Late February to early April

 

How to plant and aftercare Plant the onion sets (like small bulbs) so that the tips are just showing above the soil, plant them in rows with about 7.5cm (3 inches) between sets and about 25cm (10 inches) between rows

(Close spacing will give smaller onions than wider spacings)

Onions must be thoroughly dried before storage, if the weather is fine, the onions may be laid on the surface of the soil to dry naturally - otherwise spread them out under cover to air dry. When dry, cut off the dead leaves before storing.

 

Time from planting to harvest About 22 weeks (depends on variety)
   
 

Onions - Spring

Where to sow

Outdoors in open ground

 

Site/Soil Open, rich, well drained, well dug. Lime if acid. Preferably manured previous Autumn, do not plant or sow on freshly manured bed.

Avoid planting in an area where the previous crop was of the onion family.

 

Sowing time

March to June for summer/autumn harvest

July to August for winter/early spring harvest

 

How to sow and after care

Sow spring onion seeds very thinly in 1.2cm (½ inch) deep drills, leaving about 15cm (6 inches) between rows

Make a number of successive, small sowings of spring onion seeds to extend the harvest without producing a glut

Do not thin the spring onion seedlings as they grow

Protect using cloches from September onwards in cold areas

 

Time from sowing to harvest

about 12 weeks

 

   
 
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