I went out to my veg plot last weekend and found that my onions and shallots had bolted. Once I'd overcome my disappointment and finished cursing the weather, I realised that it wasn't the end of the world when I decided to dig one of the bolted shallot bulbs up and was surprised to find that it was quite good actually. It had developed about seven shallots, they were small and had very thin skin, but definitely shallots and big enough to use!
Why do onions bolt?
Onions, shallots and garlic are all part of the Allium family, a plant that naturally flowers once every two years. But flowering (or bolting) isn't such a great thing when you're trying to grow lots of good-quality bulbs to eat.
Usually, given normal summer weather conditions, it's easy to grow a good crop of onions, shallots or garlic without them bolting before they reach maturity. But the weather this summer has been exceptionally wet with temperatures barely reaching average, and it's encouraging onions all over the country to bolt early. All's not lost though! Despite the fact they've bolted, you can still use them and they still taste great, they just don't store as well as fully mature onions.
What to do when your onions or shallots bolt
As soon as you see them develop flower heads you should either snip off the flower at the top of the stalk or, if the stalk is quite thick, snip the whole thing off about 1 inch above the bulb (but not the leaves). Doing this stops the plant from wasting energy on making seeds.
Once you've snipped the flowers off they can be left in the ground or harvested. Those that are left in the ground won't develop any more, but it is a good way of keeping them until you want to use them. If an onion has bolted it's not necessary to wait until the foliage turns brown before you harvest them, in fact leaving them that long could cause them to start to rot or become woody.
If some of your onions or shallots have bolted but others haven't, always use the bolted ones first. The un-bolted bulbs have a good chance of going on to reach maturity and can be harvested later.
Once you've harvested your onion or shallot bulbs that have bolted, don't worry about drying them out as they won't store very well anyway. They'll keep for a week or so in the cupboard, but it's best to use them straight away while they're fresh. If there are too many, they can be chopped and frozen to be used in future recipes.
How to avoid bolting onions in future
The best thing you can do to avoid bolting is to plant 'heat treated' onion sets.
Marshalls heat treated onion sets include Hytech, Hyred, Fen Early, Red Fen and Rumba, and will be available to buy from next month. These onion sets can be planted in the autumn for an early summer harvest, or stored and planted during spring for a later summer harvest.
There are also lots of varieties available with good resistance to bolting. These include Onion Troy, Onion Stuttgarter Stanfield, Onion Autumn Gold, Onion Sturon, Shallot Zebrune, Shallot Biztro, Shallot Yellow Moon and Shallot Picasso - many of which are availble to buy now, and the rest are new and will be available to buy from Marshalls from next month!