There's nothing worse than going to your vegetable plot and finding that your onions and shallots have bolted. But it's not the end of the world, you can still harvest a good crop, the vegetables may just be a little smaller.
- 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. Bolted onions will 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.
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 if the spring and summer weather is exceptionally wet and chilly, it encourages 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.
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 Rumba, New Fen Globe, Fen Early, Red Fen and Red Ray, and are available to buy between autumn and spring.
Heat Treated Onion sets can only be planted from Mid March. They arrive with us after a minimum 12 weeks of heat treatment for immediate despatch and immediate planting into pre warmed soil. Prepare your planting bed and Pre warm your soil from Mid February. Using fleece or plastic cloches, or covering the ground with fleece held down with pegs. Plant the onions as described and keep cloche or fleece on for the first few weeks. Remove once the plant tip has started growth.
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 available to buy from Marshalls as seeds and sets throughout autumn and spring.
Buy online onions and shallots from award winning online retailer Marshalls Seeds.