How to Plant, Grow and Harvest Onions
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How to Plant, Grow and Harvest Onions

This easy step by step guide with photos shows how to plant, grow and harvest onions in your home garden. Onions are grown all year round in most climates and are used almost daily in cooking which makes these bulbs a must for the home vegetable garden.

Onions are closely related to leeks, garlic, shallots and chives. They have been cultivated for almost 7,000 years in many parts of the world. Ancient Egyptians revered the onion for its shape and rings which they believed represented eternal life.

Onions germinate easily from seed and can be either sown direct or germinated in a pot or punnet then transplanted when they are big enough to handle.

When do you plant onion seed?

In warmer climates onion seed is sown in the fall or autumn however in cooler climates it is best to plant onions in the spring. As onions store well it is not necessary to plant successive crops unless you don’t have a lot of room to store the onions once harvested.

Onion seedlings planted in a pot.

What is the best location for growing onions?

Onions like a full sun position with well drained soil. Poor or heavy soils should be improved with dolomite or compost. Onions don’t like hot summers however they can be successfully grown in shade houses during the summer months.

Planting, Growing and Harvesting Onions

Tools and Materials Needed

  • Onion Seeds – These Sweet Spanish Onion Seeds have a 90% germination rate and come in a value pack of 300. (Paid link)
  • Aged Manure or Compost
  • Liquid Fertilizer – This Kelp Seaweed Concentrate is 100% organic and great for your soil. (Paid link)
  • Shovel
  • Trowel
  • Mulch
  • Twine or String – This highly rated durable Twine has many applications in the home and garden. (Paid link)
  • Scissors
  • Box
  • Pots or Punnet and Saucer (Optional)
  • Seed Raising Mix (Optional)
  • Mist Spray Bottle (Optional)

Instructions

How to plant, grow and harvest onions in the home garden.

  1. Germinating Onion Seedlings in Pots

    To raise seedlings; fill the pot or punnet with seed raising mix then place in a saucer and water well. Sprinkle the onion seed over the top then cover with ¼ inch (5mm) of soil. Keep moist with a mist sprayer. Place in a warm windowsill with good air circulation.

    Using a mist spray bottle to keep onion seeds moist.

  2. Sowing Onion Seed Direct and Soil Preparation

    To sow onion seed direct; first prepare the soil by adding a few handfuls of compost or aged manure then dig in well. Make rows with your trowel 16 inches (40cm) apart then water. Sprinkle the onion seed along the rows then cover with ¼ inch (5mm) soil. Keep moist with a mist spray.

    Soil prepared for planting onions with rows.

  3. Transplanting Onion Seedlings

    Seedlings will emerge in 7 to 10 days in warmer weather and up to 2 weeks in cooler weather. Seedlings can be transplanted or thinned out when they are 4 inches (10cm) tall. Space onion seedlings 4 inches (10cm) apart in the rows.

    Transplanting the onion seedlings to their final position.

  4. Onion Plant Care

    Mulch around the onions then apply liquid fertilizer every 2 weeks and water regularly.

  5. Harvest Time

    Onions take 180 to 240 days to reach maturity. The bulbs are ready to harvest when the leaves begin to dry out. If you are experiencing difficult climatic conditions which cause the leaves to bend over and don’t stand up again then the onions can be harvested early.

    Onions with outside leaves dried ready to be harvested.

  6. Harvesting the Onions

    Onions can be left in the ground until the leaves completely dry out or they can be harvested as the outside leaves begin to brown. Water the onions well then use the trowel to angle under the bulb being careful not to damage the bulb itself. Gently lift up then pull out of the ground.

    Digging the onions out of the ground with a trowel.

  7. Remove Excess Soil

    Use a soft brush to gently brush off any excess soil without damaging the drying outer skin.

    Using a soft brush to remove excess dirt after harvesting the onions.

  8. Tying Onions Together for Drying

    Place half a dozen onions together then tie twine or string around the top of the bulbs leaving enough string for hanging.

    Tying onions together with twine for hanging.

  9. Hang the Onions

    Find a shady place with good airflow to hang your onions such as a garage, under a tree, porch or in a shade house. Tie or hang the bunch up high enough so they are out of the way and hang freely.

    Hanging bunches of onions to dry in a shadehouse.

  10. Leaves Completely Dry

    Once the leaves are completely dry take the bunch down then dust off any dirt. Depending on the humidity and temperature they can take up to a month to dry.

    The hanging bunches of onions have finished drying.

  11. Cut the Leaves

    Cut the dried stems just above the bulb with pruners or scissors. Hang onto the dried leaves.

    Cutting the dried leaves off of the onion bulbs.

  12. Storing Onions

    Store the onion bulbs in a cardboard, wood or Styrofoam box layering the leaves and onions. The dried leaves will help to create airflow around the onions and prevent mould. Store in a cool, dry place out of direct sunlight.

    Storing the onions in a box with their dried leaves.

Tip

Keep an eye on stored onions and discard any which have become soft. Sometimes onions will begin to sprout. It is best to immediately use sprouting onions otherwise they will need to be thrown out.

Never put onions in the compost heap. They are toxic to worms.

Onions are sweeter right after they have been harvested and are perfect for salads.

Do you have sore knees when gardening? Try these top rated no cry Knee Pads, perfect for gardening. (Paid link)

Are you looking to add more vegetables to your garden? Try these guides to growing Leeks, Garlic, Beetroot or Potatoes.

For more information on growing vegetables, see this guide to Vegetable Gardening or this Homesteading guide to get more out of your home.

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