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
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.
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.
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.