What I Know About Growing Onions

This is only my second year growing onions (brown and red), so this isn’t a long blog with endless tips and tricks because I am still learning as I go but thought other beginners might find it useful.

I think onions are one of the most used vegetables in the kitchen and I’ve loved growing them over the past two years, and hope to have even more in this years harvest. Onions are pungent though, even when they are growing they can smell strong - but that’s actually a good thing for a gardener as the scent can deter pests so having them in the middle of your vegetable patch or raised bed can help protect your other vegetables.

I’ve also only ever grown onions from ‘onion sets’ and not seed - each year I’ve started more and more from seed but initially I bought starter plants to fill my raised veg beds. I think this is the best way to get started with any vegetable growing by the way, it’s much easier and quicker to get a harvest and you can work out quickly what grows well and what you end up eating or wasting in terms of how many plants you need of each vegetable for the next year.

WHAT IS AN ONION SET?

Onion sets are basically just partly grown or immature bulbs which look like small onions already, when they are planted they will continue to grow to full size onions. They are the easiest way to grow your own, and can be bought in bags of 20+. You can buy good quality onion sets online, from specialist Plant, Seed & Garden Suppliers like Dobies or Suttons, or from your local garden centre. I got mine from Knights.

ONIONS VS SHALLOTS

There is debate in the kitchen world about the difference (or lack of) between onions and shallots and how they can be used and/or substituted in recipes. But when it comes to growing them I was surprised to find that shallots grow in clusters (more similarly to garlic), whereas onions are a ‘loner bulb’ so each seed or set produces just one onion. This impacts the spacing required when planting them. I’ve also planted shallots this year (or the first time), so I’ll keep you updated on that success too.

OVERWINTERING

I like to overwinter my onions, it means the veg bed is still used in the colder months, and also means an earlier harvest freeing up the patch for other later growing vegetables.

To overwinter your onions you should plant your onions sets in October (and they should be ready to harvest late May-June).

Raised beds are perfect for overwintering vegetables like onions - it’s essential the soil is not going to get waterlogged over the wetter months as this can cause the onion bulbs to rot.

PLANTING AND SPACING

The more space onion sets have the bigger they will grow, so I’d recommend spacing them out (in all directions) between 4-6” to get large onions. If they are closer together you could harvest every other onion earlier as a ‘green onion’, leaving the remaining ones to grow more in the new space - although I’ve not tried this technique before as I have ample room.

If you were to opt for the seed approach, onion seeds can be sown close together, and thinned out once the seedlings have grown. Maybe next year I’ll try them from seed.

Ideally onions should have full sun exposure - especially if you are overwintering them when ever inch of sunlight will be essential.

SPOONING AND TRIMMING

This will be the first year I try these techniques. Spooning onions requires you to scrape away some of the soil from the top of the onions so you can see a small part of the bulb - as I’ve overwintered mine I am only going to do this from April onwards so that any late frost or cold weather doesn’t damage them.

Trimming the green shoots above the ground to 5” will help keep all the growth in the bulb and not in the stems. As you’ll notice last year the green shoots on our onions were thick and extremely tall - I’m excited to see how much bigger the onions will be this time using this technique.

These techniques are definitely not essential (last years harvest proves that!) but regardless of how short you decide to keep the stems you should always cut off any onion flowers you see as buds.

*Last years onions grow very tall and thick, this year we will be trimming them to keep the growth in the bulb not the stem.*

HARVESTING ONIONS

Your onions are ready when the tops have been green, then go yellow and then wilt over (this final stage is a sign the onion is no longer growing). You will also notice that each onion pushes itself up to the surface too so you can see they are big, ripe and ready!

To harvest your onions, gently pull them with a firm grasp, or scoop them carefully out of the ground and shake off any excess soil. They should pull out of the ground fairly easily with the right wiggle and pressure.

Once harvested, onions should be left flat for a few days (preferably a week or two) in the garden or on a shed floor to dry out the long bits at the top. Once dried they can be strung up, plaited or just placed carefully into a net bag to be stored

ONION STORAGE

When it comes to storing your home grown onions there are some non-negotiables to remember. Red or white or brown onions should all be stored in a cool, dry, well-ventilated space out of direct sunlight. Pick an unheated room in the house or a dark spot in the shed. If you have any onions with soft patches, surface bruises or thick necks then use these up as soon as you can instead of storing them for the future. A well stored onion can be kept for up to 10 months and still be perfectly edible and super tasty - mine have never lasted this long as I’m always cooking with them almost as soon as they are harvested!

OTHER ONION FACTS

I’ve also learnt along the way some other interesting facts like onions were (and are) considered an aphrodisiac by the ancient Greeks, ancient Egyptions, Hindu’s and the French! And perhaps more useful to know, onions can help hayfever sufferers with their natural and potent anti-histamine and anti-inflammatory properties!

HERE’S WHAT I KNOW

You can grow onions from seed (which I’ve not done), or buy ‘sets’ of small onion bulbs
Plant onion sets with at least 5” of space around them so they can fully grow
Over wintering can free up space in your veg bed or planter for more vegetables by providing an earlier harvest. Make sure the sets are planted in October in full sunlight
Spoon your onions by digging the dirt away until you see the top of the onion bulb. This stops it growing too much of the green shoot out the top, and concentrates the goodness and growth into the bulb (this will be my first year trying this method)
Keeping your onions short - similarly to spooning to keep the goodness growing in the bulb as much as possible you should trim the green tops at about 5” above ground level. If you keep the onion stems short you should get larger onions although this will impact the ability for them to be plaited for storage.
They are ready when the tops have been green, then go yellow and wilt over - they push themselves up to the surface too.
Store onions in a dark and cool place for up to 10 months