How to Grow Onions from Bulbs: A Simple Guide to Growing Onions

Onions are a versatile vegetable that can be used in many different dishes. They can be grown from seeds, but it’s quicker and easier to grow onions from bulbs, which are known as onion sets. In this guide, you will learn how to plant and care for onions so that you can enjoy this delicious vegetable all year long.

How to Grow Onions from Bulbs

Onions growing in a garden

When is the Best Time to Plant Onion Bulbs?

Autumn or Spring

Onion bulbs can be planted in the spring or autumn, but if you live in an area with a mild climate, you could even plant onions year-round. In general, onions prefer cool weather though, and will not do so well in very hot weather.

If you live in an area with harsh winters, it’s best to plant your onions in late summer or early autumn. This means they have time to establish themselves before the cold weather sets in, ready for a harvest the following year. Otherwise, you can plant them in the spring for an autumn harvest in the same year.

Where is the Best Place to Plant Onion Bulbs?

Onions prefer well-drained soil that is rich in organic matter. If your soil is heavy or clay-like, you may want to consider planting your onions in raised beds or mounds. This will help improve drainage and prevent the bulbs from rotting.

Full sun is best for onions, but they will also do well in partial shade. If you live in a very hot climate, some afternoon shade may be beneficial to prevent the bulbs from scorching.

What you’ll need

  • A packet of onion bulbs (also known as Onion Sets)
  • A sunny spot in your garden
  • Well-drained soil
  • A dibber tool or something to make a hole in the soil
  • Water

Planting onion bulbs in rows in a bed

How to Plant Onion Bulbs

1. Choose a sunny spot in your garden that has well-drained soil. If your soil is particularly heavy or clay-like, you may want to add some organic matter such as compost or manure to help improve drainage.

2. Make some small holes in the soil around 10cm apart

3. Place the onion bulbs in the holes so that the pointed end is facing up

4. Backfill the hole with soil until the tip of the bulb is just showing

5. Water the bulbs well, making sure to soak the soil around them.

6. Mulch around the onions with straw, hay, or shredded leaves to help keep the soil moist and prevent weeds from growing.

7. Onions are ready to harvest either when the onions get large enough to eat or once the tops begin to turn yellow and fall over. To harvest, simply lift the bulbs from the ground with a garden fork.

How Long do Onions Take to Grow?

Onion bulbs typically take a few months to mature. However, this will vary depending on the variety of onions you are growing as well as the climate conditions.

  • Onions planted in the autumn should be ready to harvest in spring or early summer
  • Onions planted in the spring should be ready to harvest in late summer or early autumn

Onions growing in a garden in the sunshine


If your onions are not growing well, there are a few things you can check:

Are they getting enough sun?

Onions need at least 6 hours of sunlight per day

Do they have enough water?

Onions need to be kept moist, but not wet. Water them regularly, making sure the soil is always damp but not soggy

Are the onions overcrowded?

If the bulbs are too close together, they will not have enough room to grow properly. Thin them out so that they are around 10cm apart

Are the onions being affected by pests or diseases?

Onion flies or maggots, thrips, and fungal diseases can all affect onion growth. Check your plants regularly and take appropriate action if you see any signs of pests or disease. You might consider covering your onions with garden fleece. You can also grow parsley as a companion plant, as it’s said to repel onion flies.

How to Store Freshly Harvested Onions

Once harvested, brush off any excess dirt and allow the onions to dry in the sun for a few hours. This will help to prevent them from rotting. Trim the roots and the tops, leaving around 5cm of stem attached to the onion. Onions can be stored in a cool, dry place such as a garage or shed. Place them in a crate or basket, making sure they are not touching each other. Alternatively, you can hang them up in meshes or old tights. Onions will typically keep for a few months if stored correctly.

Freshly harvested onions from the ground

Onion Varieties to Try


These golden-skinned onions grow well and mature early in the year. When they’re harvested, the onions keep well, so can be enjoyed for a long time.

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This is a great-tasting variety, full of flavour. Plant in spring and enjoy round, straw-coloured onions that mature in August.

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These firm, semi-flat onions are a tried and tested old favourite that also stores very well.

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Red Baron

A great red onion variety with good yields and a beautiful flavour. It also keeps well and makes a tasty, vibrant addition to the salad bowl!

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Growing Onions Summary

  • Plant in autumn or spring
  • Plant 10cm apart in well-drained soil
  • Place bulbs in soil with tips just showing
  • Harvest when big enough or the leaves are yellow and falling over

Hopefully you’re now ready to grow some fresh, tasty onions. They’re such a useful and versatile vegetable to have in the kitchen and are great for adding to many dishes, such as curries, casseroles and stews. You could also add them to a fresh salad or even make onion soup. Enjoy!

Have you been growing onions this year? Which varieties are your favourites? Which will you try next? Let us know in the comments!


You might also like this post about how to plan a vegetable garden.


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