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Sow outside
Plant outside
Showing schedule for Southern England in United Kingdom

Soil facts and preparation

Quick facts..

  • Soil Type Fertile, Firm and Well Drained
  • Ideal Ph range 6.0 to 7.0
  • Site Full Sun
Dedicate a large area for your onions if you intend to have enough to meet your culinary needs. Your onion plot should be in full sun and have well drained, rich soil containing plenty of organic matter. Dig in plenty of compost in preparation and add a general purpose fertilizer a week or two before planting or sowing.

Note onions do not like high levels of Nitrogen in the soil so avoid sites where fresh manure has been added in the last year. Onions prefer neutral or slightly alkaline soil so add lime if your soil is acidic.

Pick a spot where you have not grown any members of the onion family in the past 3 years. Ensure the area is completely weed free.

Sowing and planting

Quick facts..

  • Germination 1 to 1 days
  • Sow 15mm deep
  • Sow Spacing 150mm
  • Rows 300mm apart
if growing from seed ensure that you have new seed - onion seed doesn't seem to store particularly well. You can sow seed directly in the onion bed or start off in small pots or cells and transplant when the plants are approximately 14cm tall.

Plant sets so that their tips are about 1cm below the soil. Do not plant too deep as this may result in onions with 'thick necks' that do not store well. Create rows of onion sets 15cm between plants and 30cm apart.

Onions are susceptible to bolting, however choosing sets that have been heat treated minimizes the risk.

Growing a bumper crop

Keep the onion bed weed free. The roots of onions do not penetrate very deep so do not let the soil dry out, water regularly especially in dry weather.

Harvesting the fruits of your labour

Quick facts..

  • Yield 250g per plant
Lift the Onion when the leaves have started to turn brown and appear to be dying. Store the whole plant in a warm dry location for 2 weeks to dry the outer skin of the bulbs.

Do not attempt to store onions that have developed a thick neck or have damaged bulbs as they are likely to rot, use within a few days.

Onions can be stored for up to 6 months in a cool dry place. Either tie in plaits, put in a net or old stocking or store in boxes.

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