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?
Donald
AOnions are biennials which means they usually grow during year one and flower and set seed in year two. But when th eplant feels stressed, it panics and rushed to reproduce by flowering. It then sets seed before it’s fully grown, a condition known as ‘bolting’.
Examples of stressful situations where onions are likely to bolt are when the growing conditions are either too hot and dry, or too cold. 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, protect them from undue stress by keeping their conditions as constant as possible.
Cover them with horticultural fleece if a cold snap is expected in spring, and keep them well-watered during hot spells. As this will not only ensure the plants have plenty to drink, but will also stop them getting too hot.
Another way to help prevent bolting is to grow varieites known to show resistance to bolting. Some great examples include ‘Sturon’, ‘Jet Set’, and ‘Stuttgarter’.
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.
David Domoney is a Chartered Horticulturalist, Broadcaster, and Author. David has worked with a number of the UK’s leading garden retailers as a plant buyer and strategic consultant. With more than 30 years experience, in horticulture, David is as passionate about plants now as he was when he bought his first plant at a village fete.
Thanks that was so helpful
Well done. Thanks for that. Good advice. I’ve always eaten them just wasn’t sure whether I should have been
I garden in Cyprus so weather extremes are common. I planted onion sets instead of seed this year as I heard they are less susceptible to bolting. The white onion sets have almost all bolted, but the red onion sets seem to be free of flower heads.