A Complete Guide to Growing Onions | Love The Garden

How to Grow Onions

Lucy Pitts's picture
By Lucy Pitts, Garden Enthusiast
A selection of Onions.

Used in cooking and traditional medicines since ancient times, the onion is a staple for many of our kitchens as well as a great vegetable to grow in our gardens. The fact that they are bursting with flavour and goodness, easy to store and grow all year round, all makes growing your own onions another obvious choice for the vegetable patch or allotment and one of our all-time favourites.

Growing Onions From Seeds or Sets  

Onions take 3 – 4 months from planting from seed to harvest, and the first choice you have to make is whether to plant onions from seed or from sets. Sets are small, immature onions planted in late spring or summer and available at most good garden centres or nurseries. They’re easier and quicker to grow, especially in colder regions and can be more resistant to problems but you may find you have a wider choice of variety if growing from seed.

And think about what you want to do with your onions as you decide which onions to grow. Are you looking to pickle them or use them in salads and cooking? Do you want to grow spring onions and when will you be planting them? What are your weather conditions and what does your local garden centre recommend as the best for your area?

Onion seedlings.

Preparing to Plant

When growing onions, they prefer neutral or slightly alkaline soil and they’ll need a well-drained and sunny spot. Don’t plant them into freshly manured soil (if you need to add manure, do so a couple of months in advance and dig well in so that it has time to settle) and if your soil is heavy, consider breaking it up by adding grit or a good organic compost. Onions are not suitable for shallow grow bags but the deeper filled planters are a good choice for those with no space to plant out in the garden.

Get Planting

You can grow onions all year round. If growing from seed it’s best to plant them inside at this time of year (January / February) and them plant them out in late March to April. Plant the seeds in clusters of 5 or 6 but if you are growing from sets wait until the spring and then plant them so that their tips are just showing, about 10cm apart. Spring onions can be planted from April. If you experience a dry spell then water your onions and you can add a light general purpose fertiliser in early summer.  

Growing your own onions doesn’t require much ongoing maintenance, just make sure you keep their beds well weeded and watch out for the birds. When their foliage starts to go yellow (3 -4 months after planting as seed, less if planting from sets), they are ready to lift.

Different ways of planting onions.

In the past it was considered a good idea to bend the onion foliage to encourage the harvest but this is no longer good practice …just wait for the leaves to fall back naturally. Finally, if you can, harvest them on a dry, sunny day by lifting them with a fork, cleaning off any excess soil and leaving them on top of the soil to dry off.  

Did you Know? 

It’s not hard to believe that onions are low in calories and fat but did you know that they have a whole myriad of other qualities that make them an essential part of our diet? There’s evidence that they can reduce the risk of heart disease, are anti –inflammatory, help with cholesterol, contain anti-oxidants and are anti carcinogenic.  

They are also high in iron and are good for blood glucose control. In some parts of the world they are used for the treatment or stings or bites, warming the feet and even sore throats! So perhaps it’s no surprise that the ancient Egyptians worshipped them as representing eternity and used them in their burials. But above all else of course, they add that essential ingredient and flavour to many of our everyday meals.  

A selection of harvested onions for culinary use.
Imade Credit: NaturalOne.org

 

Onion Pests and Diseases

There are a number of specific pests and diseases that are common with onions. The common pests are the Onion Fly, the Lesser Bulb Fly and Thrips. Even though there are few pests that occur in onions they do so in abundance so watch out and be sure to take every precaution to prevent them in the first place.

When it comes to diseases there are many more that can affect growing onions. Some of these diseases include Downy Mildrew, Smuts, Leaf Blight and Onion White Rot. Most of these except the latter is treatable. Make sure you are planting in healthy soil to avoid these diseases.

Our Top Tip for Avoiding “Onion Eyes” 

Everyone has a tip for how to avoid sore eyes when chopping onions from putting a spoon or a piece of bread in to your mouth. But our favourite and the one we’ve found most effective is putting the trimmed onion in water (or holding them under a running tap) for a few minutes before chopping and slicing.  

What are your “onion eye tips” and where did you learn them? Was it from family legend, a top chef or a neighbour? Share your tips with us and let us know how you get on with growing your own onions on our social media pages, or leave us a comment below. Remember we always love to see your photos so feel free to share them!  

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