New World Little Gardens

redonion pattern
red onion

Red Onion

Allium cepa

One of the most essential vege crops, onions take a few months to reach full size but are well worth the wait.

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Getting started

  • Put the soil tablet on a saucer and pour 50ml of water over it.
  • Put on gloves and mix the water into the soil with your hands to make a wet mixture. Watch the soil expand.
  • Use most of your soil to fill up the pot to around 2cm below the top.
  • Now place your seed mat on top of the soil (take care not to press down too hard).
  • Now use the rest of your soil mixture to cover the seed mat.
  • Remember to wash your hands when you’re done!

How to keep your Little Garden healthy

  • Place the pot on a clean saucer in a place with enough light, but not directly in the sun.
  • Check the soil in the morning, and before bed. If the soil feels dry and crumbly, pour a small amount of clean water over the surface.
  • Within 2-3 weeks you should see a little plant appear from the soil. That means the seeds have germinated and will be ready soon to move into a bigger pot or garden.
  • If more than one little plant grows, you can thin your red onion seedling by choosing the strongest-looking one and removing the others.

When your seedling is ready to go in the garden

  • When the onion is about as tall as your finger (in approx. 4-5 weeks), it’s ready to shift into the garden or a pot.
  • Get your onion used to life outside: you can harden off your red onion by putting it in a warm and sheltered spot for 1-2 hours a day and return inside for the night. Do this for 4-5 days, leaving it outside for a little longer each day before you shift it out into the garden forever.

Planting best practice

  • Give your onion full sun with free-draining soil. In partial sun it won’t produce fat, juicy bulbs.
  • Onions don’t like competition from other plants, so they need lots of space. Plant onion plants 15cm apart in rows that are 30cm apart. Ensure their spot is weed-free and keep weeding around them while they’re growing. Be careful not to disturb the developing bulb.

Look after your plant while it’s growing

  • Onions need constant moisture, so water 1-2 times a week while the bulbs are forming, more often if the weather is dry. 

Harvest time

  • Onions are slow-growing plants. After 4-5 months the tops of the plants will start to turn yellow and fall over. That’s a sign that the edible bulbs under the ground are ready to harvest.
  • Lift out the bulbs carefully by hand. Leave them to dry in the sun for 1-2 weeks, turning them every now and again, to dry their outer skin. You can leave them on the ground if it’s sunny or dry. You can also hang them on a fence, or the roof in a dry and airy garage or potting shed.

Watch out

  • If conditions are hot and dry, tiny thrips can attack your onions, causing silver or white flecks on the leaves. Treat with a pyrethrum-based insecticide. To avoid a thrips infestation, keep the area around your onions weed-free, and water regularly while the bulbs are forming. You can also plant a Little Garden Purple Tansy nearby to bring in hoverflies, whose larvae eat thrips.
  • Onions can be prone to the fungal infection such as downy mildew, especially if under-watered. Water regularly and ensure your onions have good air circulation, to avoid the humid, close conditions that lead to problems with fungal infections.

Red Onion in your gardens