Onion flowers. akiyoko/Shutterstock.com

Onion flowers. akiyoko/Shutterstock.com

QI have been growing onions from seed this year and at least a third of them have gone to seed. Where am I going wrong?


AIt’s common for onions to bolt (run to seed suddenly) when there is a cold snap – it’s as if the plant thinks winter is setting in and quickly throws out some seeds.

They can also bolt in very hot weather – they get dry, panic and run to seed.

This is a problem because when the plant puts its energy into creating seeds, it stops growing the bulb.

Onions are temperamental and susceptible to changes in their environment. To stop them bolting, keep their conditions as constant as possible. Cover them with horticultural fleece if a cold snap is expected in spring, and keep them well-watered in any hot weather.

Onions in the garden. Birgitta Kullman/Shutterstock.com

Onions in the garden. Birgitta Kullman/Shutterstock.com

And if you see a flower head forming, snip it off immediately before it blooms.

Dig up any onions that produce a flower stem. Once they start to set seed they won’t grow any more, and they don’t store well either.

But onions that have bolted are still edible and will taste fine, so dig them up first and eat them, leaving the others to mature in the ground.

And finally, don’t be disheartened. Professional growers suffer from onions setting seed too. Just use them in the kitchen – you haven’t lost anything.

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