Onions are used in so many recipes and form the basis of stews, soups, chutneys and stock. Delicious roasted, fried, pickled or eaten raw, as well as being easy to grow and harvest. They can be stored well into winter. Find out how to grow onions the easy way.
10 reasons to grow onions
- Large amounts of cheap seeds in packets sold in most shops.
- Seeds germinate quickly in any compost.
- You can fit approximately twenty-five onions in a 1-metre square growing area.
- Low maintenance, they just need watering in periods of drought.
- They can be stored for months, well into winter.
- You can let some onions flower and save the seeds for next year.
- They can be chopped up and frozen, to be used later in cooking.
- They are easy to prepare for cooking or can be eaten raw.
- They can be caramelised by frying slowly, which adds sweetness to dishes.
- They provide the basis for many meals by adding depth, plus they are fat-free and low in calories. They contain fibre, carbohydrates, vitamins and minerals.
Our onions last year – what we did
We sowed the seeds in early February and put them on a sunny bedroom windowsill, moved them into the greenhouse in early April, lifted them outside to ‘harden off’ mid-April, planted seedlings in the ground late April / early May, and by late August we were digging up hundreds of onions which we then left drying in our greenhouse for a few weeks.
By the end of September, we had hundreds of onions hanging in net bags in our loft, which we were still eating the following March. We kept an eye on them, eating first the onions that started growing a stem, as these would not last as long as the others. By February, as more onions started growing stems, we decided to peel, chop and freeze them for later use.
Recommended varieties: Ailsa Craig, Red Baron
How you can grow onions
What you’ll need:
- Onions seeds (red or white, or both)
- Seed trays, ideally with propagator lids
- Bag of compost
- Watering can or jug
- Sunny windowsill, and later either a greenhouse or under glass – somewhere protected from the weather
What you’ll do:
- In February, fill each seed tray three-quarters full with compost. Water the compost lightly.
- Arrange the seeds evenly over the compost.
- Cover seeds with compost so the tray is full and place on a sunny windowsill. It’s better if you have propagator lids on your seed trays.
- Water every week or so if the compost looks dry, but don’t overwater them.
- As they grow, keep giving them a trim using scissors to help strengthen the roots.
- When the weather warms up in early April, move the trays into a greenhouse or under glass. Keep watering them if they need it, but stop trimming them now.
- After a couple of weeks, lift the trays outside in a sheltered spot to ‘harden off’ for a week or so.
- Dig small holes in the ground about 15cm apart in both directions. Plant each seedling into the hole. Water well.
Caring for onions
Occasional watering is all that onions need. If you have any insect mesh netting, then covering the onions can be a good idea to protect against onion fly attack.
As the onions grow larger, some may start growing a hard central stem. If this happens then simply break off the stem low down to stop the onion from flowering (or bolting). That onion won’t grow a stem again. We have rarely found that onions grown from seed bolt anyway.
By August the onion leaves will start falling over and collapsing – this is normal and expected.
Harvesting onions
When the onion’s leaves have fallen over or collapsed, you can harvest it.
Carefully loosen the ground with a garden fork and lift. You can harvest as few, or as many, as you wish, but make sure you have lifted them all by mid-September.
Problems
As long as you water them in periods of drought, you shouldn’t encounter any problems.
In 2021, our onions showed strange signs of damage. Find out how we saved 95% of our onion crop after an allium leaf miner attack.
Storing onions
Onions won’t last that long in the kitchen because the heat and moisture will encourage them to start growing, but don’t worry find out how to easily store onions for months by following our storage guide.
