Fall for Onions in Autumn

, written by Benedict Vanheems gb flag

Fall-planted onion

Of all the vegetables our green fingers tend it is the onion that boasts the oldest pedigree. Seeds of this flavoursome favourite have been found in the tombs of ancient Egyptians. Getting on for well over five millennia old, they offer compelling evidence that onions have been around for quite a while. Intriguingly, the onions we grow don’t naturally occur in the wild, suggesting that this member of the Allium family was also one of the first plants to be domesticated by man.

Today’s onions are grown just about anywhere it rains – i.e. most places! They’re certainly high up my list of must-have crops thanks to their consistently providing a near failsafe staple. Assuming you can give them a place on the plot that’s bathed in sunshine and enjoys a free-draining fertile soil, onions will do their thing for you too.

Set to it with Onion Sets

Onions can be raised from seed but a far easier alternative is to start them off from miniature bulbs called ‘sets’. Sets are simply immature onions that have been started off commercially then dried to suspend growth before being sold on to the likes of you and me. The tiny bulbs are no wider than 2cm (1in), usually less, and are guaranteed to be free of viruses ensuring a reliable, eager-to-please product. Plant sets and you’ll suffer none of the vagaries of erratic germination – my springtime sets achieved a 99.5% success rate (yes, one of the 200 I planted stubbornly failed to sprout, denying me the satisfaction of a perfect strike rate).

But while intuition might dictate that spring is the best time to begin growing onions, autumn works well too. Planted at this time of year the tiny bulbs readily put down roots before ticking over quietly for winter ready to take off that much earlier in spring. Autumn-planted sets can yield their pungent haul by early summer, often a full month earlier than spring-planted sets. If you’re an onion obsessive like me you’ll appreciate that this is very good news indeed.

Planting onion sets
Planting onion sets

Planting Onion Sets

Autumn sets follow seamlessly on from summer crops. If you have grown potatoes this season then plant them here, as the soil will have been well dug for this crop and will, hopefully, be reasonably free of weeds. Rake in some general purpose fertiliser about a week before plating to give the soil a boost of nutrients; Growmore or blood, fish and bone is just the ticket. If it’s been very dry where you are then thoroughly soak the ground – you want the sets to be stirred into action as soon as possible.

Onions prefer quite a firm soil, which is where a rather eccentric cultivation technique comes into play. Just before planting, shuffle up and down the onion bed, taking baby steps to push down the soil. This necessary step (or rather steps) in the process may raise a few eyebrows but will ensure the crumb structure of the soil is compacted to give the roots the support they need.

Plant your sets about 2cm (1in) deep so that just the tip of each set pokes proud of ground level. Space each one 7-10cm (3-4in) apart in rows 30cm (12in) distant. Birds have a habit of mistaking the papery tips as tasty morsels, pulling up the sets as they grapple with what they presumably believe to be a juicy worm. Set tips are simply the old leaves of the immature plant, so one way around this is to carefully snip them away down to the shoulder of the miniature bulb before planting. Once your sets are in situ keep the ground clean by hand pulling weeds so as not to damage or uproot the baby onions.

Frosty reception

Extreme cold will kill off overwintering sets. Alas, this means that while those growing in a more temperate climate can autumn plant, it’s not for everyone. Those in USDA zones five or below will have to wait until the soil is workable in spring before planting the conventional way. Furthermore, while British gardeners are spoilt for choice when choosing sets for autumn planting, the same isn’t true for folk in North America, though young seedlings are often found for sale instead.

Red onion 'Electric' sets
Red onion 'Electric' sets. Image courtesy of D.T. Brown Seeds

Not all onions are suitable for autumn planting, either, so be guided by the variety’s description. Two of my personal favourites are ‘Electric’, a beautiful red onion with an almost pink-tinged flesh, and ‘Senshyu Yellow’, a Japanese type with a slightly flattened profile. Of course, there are plenty more out there. While everything else is shutting down for winter, it’s a pleasure to be getting something into the ground in preparation for next year’s bounty.

By Benedict Vanheems.

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Show Comments


"Don't forget Garlic and Shallots there are many more varieties that the ones you can get from the supermarket here in the UK. Any advice on how to grow from seed would be appreciated."
Helene Wiltshire UK on Sunday 11 September 2011
"Helen, we have information on growing shallots (including from seed) in this article: http://www.growveg.com/growblogpost.aspx?id=120 and on garlic here: http://www.growveg.com/growblogpost.aspx?id=110"
Jeremy Dore on Sunday 11 September 2011
"I have more of a question than a comment. I have never overwintered but want to try it this year with my established garden. I want to do leeks, onions, garlic and shallots. All will be from seed. Should I sow the seed directly or start it in my greenhouse first? I have some already started. Should I cover the beds? I generally do with my early spring planting. I live in Oregon right outside Portland. Any help or direction on where to find information over wintering is appreciated. "
Lynda on Wednesday 14 September 2011
"Lynda, leeks should have been started from seed in spring then planted out in summer for overwintering. You may be able to find ready-grown seedlings in garden centres and it may be worth a punt planting these out now as there's still a month or so of growing season left, especially in the mild Pacific Northwest. Garlic and shallot sets can be planted out where they are to grow in October. They'll root quite happily before winter arrives and then sit through winter to shoot early next spring. By planting in fall/autumn you'll ensure plump and tasty bulbs in good time next summer. Onions for overwintering may be sown now (early fall/autumn) into outdoor seedbeds. Sow into 1cm (0.5in) drills spaced 25cm (9in) apart. Transplant the seedlings in spring into a prepared bed so the seedlings are about 15cm (6in) apart in rows 30cm (12in) apart. You shouldn't need to cover the beds in your part of the US, though a cover of horticultural fleece certainly wouldn't do any harm and may speed things along towards the end of winter."
Benedict Vanheems on Friday 16 September 2011
"Thank you for this very informative article, Ben. It answered a couple of questions that had been rattling around in my head, not the least of which was "why do birds pull up our onion sets?" Now I know! Makes sense! Is there an onion variety in the UK (set or seed) to grow in autumn for pickling? I know about shallots, but I wondered about something along the lines of a Paris Silverskin, etc. Many thanks! "
Phyllis Smith on Monday 6 August 2012
"Hi Phyllis. As far as I am aware there isn't a variety of pickling onion suitable for autumn sowing. Pickling onions especially prefer light soil, so the wetter, colder winter may not be suitable for them."
Benedict Vanheems on Tuesday 7 August 2012
"Thanks Ben, that makes good sense."
Phyllis Smith on Tuesday 7 August 2012
"Do you have to soak the onion set roots in water before planting? Mine seem awfully dry."
Lisa on Thursday 4 October 2012
"Hi Lisa. You shouldn't have to soak them - just plant them as they come. The sets should be dry but firm to touch - ie, not soft, which would indicate a diseased set. Discard any that are soft, clearly damaged, or showing signs of disease. Just plant the firm sets. "
Benedict Vanheems on Friday 5 October 2012
"What are the best vegetables to plant in an already established garden in southern California? "
Ava on Saturday 6 October 2012
"I'm a 1st time veggie gardner here!! Planted some sets of both Texas 1015 Sweet Onions and Red Southern Bell Onions only 2-3 weeks ago. Some of the greens of the onions are either bent or falling over. They are about 8-10 inches tall. Should I be trimming them and keep them shorter or just leave them alone and trim only the ones that bend? Thanks for your advise for this new 1st timer!! :)"
Brenda on Monday 3 December 2012
"Hi Brenda. It sounds like your onions have grown in a big spurt in warm-ish weather then perhaps hit a cold spell and flopped over. You shouldn't trim off the leaves, as it's these that will generate the future growth of the onion. They will probably be fine, picking up again next spring. If you get really cold winters where you are you might want to cover the sets with horticutural fleece."
Benedict Vanheems on Friday 7 December 2012
"Very good advice. I've learned something here which I guess is the reason for blogs like this. Some time ago I did a short YouTube video on the subject of planting onion. Hope some of your readers will enjoy! http://youtu.be/77DfIVD2EMY"
Dan Owen on Sunday 16 June 2013
"Not a north QLD crop"
David on Friday 7 March 2014
"I live in southeastern Wisconsin. I can grow beautiful green onions, and have done so over the years from sets, seedlings and this year from seed started early indoors. I just haven't found the trick to getting them beyond a slim green onion into a bulb! The biggest bulb I've ever harvested is maybe 1" diameter. What am I doing wrong, or not doing right?? I've got serious onion-envy of the beautiful fat bulbs I see at the farmers market, and can't consider myself a successful gardener till I produce a nice fat onion. Any tips?"
Gina on Thursday 17 July 2014
"Hi Gina. The main thing is to keep them well watered from spring onwards. This is when the bulb will be forming and swelling. You need to plant the sets or young plants early enough too - get them into the ground by mid spring so that they have enough growing season to swell up in. After the longest day (21 June in the northern hemisphere) they tend to slow right down. So all the time before this is essential for bulb growth."
Ben Vanheems on Monday 21 July 2014
"What about planting onions now for a double harvest as you will? Or will they just not grow well in late summer? "
Kim on Sunday 27 July 2014
"Hi Kim. Unfortunately bulb onions can't be planted in late summer as they will put on too much growth to successfully overwinter, making them prone to frost damage. They will then bolt (run to seed) in the spring before they have made a bulb. You will need to wait until autumn/fall to plant relevant onion sets. If you are after an oniony hit, try sowing a few rows of spring onions, which will be ready to crop in just a few months' time."
Ben Vanheems on Tuesday 12 August 2014
"How would I determine which onion varieties are best suited for fall planting in my area in the US?"
Corey on Friday 20 February 2015
"Hi Corey. I would look at gardening/seed catalogues to see what is recommended. You could also ask at local plant nurseries, as they will be used to advising on varieties suited to the local climate. "
Ben Vanheems on Monday 23 February 2015
"I'm in zone 5 and planted onion sets in March. It's now July 24 and I can't figure out if I can plant a second crop of more sets for a fall harvest. Can you please advise me. Thank you."
Angie on Friday 24 July 2015
"Hi Angie. You can't plant bulb onions now for a crop this year - it's just too late in the season. However, if you wait until fall, you could then plant onion sets for overwintering to give an early crop next year. You will need to give them some protection - in a cold frame or similar - as the winters where you are a pretty cold."
Ben Vanheems on Monday 27 July 2015
"18/09/2022 . I also planted 108 Electric onion yesterday in a bed which I had harvested this years Sweetcorn."
John on Sunday 18 September 2022
"Hi Ben, I keep getting mixed reviews for onion sets. Some say they go to seed, rather than bulbing. How can I avoid this and get nice big bulbs?"
Louise O'Connor on Monday 2 October 2023
"If you want to plant sets, then look for sets described as 'heat treated'. This greatly reduces the risk of them going to seed. I do find that onions started from sets are slightly more likely to go to seed than onions started off from seeds. But then sets are very convenient. "
Ben Vanheems on Monday 2 October 2023

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