Short version: A sweet and mild allium (onion garlic family), that is an invasive, self-seeding, hardy, perennial that grows fine in the shade in pretty much all soil. The leaves, flowers, seed pods and bulbs taste great. There is something to harvest almost all year round and most importantly it works as a cut and come again mildly oniony vegetable over the hungry gap.
I first saw the three cornered leek (allium triquetrum), also called three cornered garlic, in a foraging book and then came across it in a friend’s garden. Not knowing what it was, she despised the stuff. She said it was garlicky, but she had not identified it so hadn’t been eating it. I could see why she didn’t like it. It had completely invaded her lawn from where it appeared to have begun in a border. After a mowing it would be hard to visually distinguish from the grass. I begged her for some for my garden and she was happy to give me as much as I wanted, as long as I was prepared to dig it up myself. I wasn’t prepared, but I was totally willing. I ended up digging it out with a soup spoon. There may have been some choice words I would not repeat to my 4 year old directed at the particularly deep bulbs.
Now that I had learnt to recognise it, I could see it everywhere. I have seen it creeping out under many many fences in the area. I have seen it in the herb garden of the local park. I have seen it coming out between paving stones. I have seen swathes of it in Green Park.
Having seen first-hand how invasive it can be I dug my new 20 odd bulbs into an enclosed bed in the front garden, under the roses. I didn’t want to keep the roses, but did because the little monkey loves them, they smell lovely and roses are apparently edible (something to explore this year maybe). Three cornered leek does fine with shade and grows very weedily so I figured it would survive regardless of rubbish conditions. Boy was I right. I left them fo r a year to acclimatise and didn’t harvest anything to let them establish. The next spring though there were plenty of new seedlings and the older plants have come back thicker and longer. This is a rampant self seeder.
How to grow
This is a non-native invasive plant listed on Schedule 9 of the Wildlife and Countryside Act so it is an offense to introduce it anywhere in the wild. Introducing it into your own garden makes it your own problem. You would think that, given that it is invasive, you would be doing someone somewhere a favour if you were to weed it out of your local park. However, it is not legal to dig up the roots/bulbs of any plant without the landowner’s permission. Besides there can sometimes be a fine line between foraging and stealing. Not to worry if you don’t know of anyone who has plants or who to ask permission from if you find it in a park, there are seeds available on the internet.
Based on where I’ve seen them growing, they can be sown or planted pretty much in any soil, with any light conditions. Most importantly, in a small garden, they seem to do well in shade. They can be used to fill up the shady areas of your garden that are less hospitable to edibles.
Once you have them though, apparently it is quite hard to get rid of them so make sure you put them somewhere where they can be contained.
If you have bulbs plant them deep as they seem to like being a good inch or two down. Seeds can be sown in early autumn as they would be naturally. The seedlings that emerge are tiny so make sure that you’ve labelled them well as they won’t look like anything edible till the next year.
You can barely see the thin, tiny seedlings
How to harvest
Harvesting can begin from when the plant is a year old. Existing bubs start poking their leaves out of the ground around October. This is also when the seedlings start to appear. The over a foot long leaves are available for harvesting from winter to summer. This makes it a good one for covering the hungry gap. The flowers can be eaten when they appear from April onwards. The flowers give way to green seed pods the size of petite pois in May. When the plant begins to die back towards the end of summer the bulbs can also be eaten but they are small and fiddly, and I rarely bother as it means less plants to harvest from the next year.
Leaves emerging 
Tiny seedlings within the bigger plants 
Beautiful garlicky flowers
How they taste
The leaves have a sweet, mild garlicy/oniony flavour. They are great raw or fried lightly. If you add them into any dishes, add them right at the end, otherwise you lose a lot of the flavour. The flowers are lovely and sweet in salads. They too carry the allium taste. The young green seed pods keep a lovely crunch when lightly cooked and are very sweet and almost fruity. It sounds terrible, but I thought of lychees. Yes… and oniony lychee sounds foul… if you’re expecting lychee and get onion. However, if you’re just expecting onion and you get a fresh fruity added flavour then it is lovely. Basically, the seed pod is the fruit of the plant, like a tomato or a berry. Sound less icky? The bulbs have a sweet mild garlic flavour.
fried seed pods and leaves 
veggies for crispy duck pancakes 
the three cornered leeks are so mild you can add a few
Warnings
I have read that eating too much can cause digestive distress. You would have to eat quite a bit. The same warning applies to all alliums anyway. In our 20s the husband (then boyfriend) and I ate a bulb of elephant garlic. It was huge – the name gives it away. It was not one of our better ideas. Also, of course if you have any sensitivities or allergies to alliums, this would not be a plant for you anyway.
A more important warning is not to grow these in areas where you have bluebells or other similar looking spring bulbs. They are around at the same time, look very similar but bluebell leaves are poisonous. Of course, the smell is a good indicator, but also three cornered leeks are so named due to the central rib of the leaf protruding out, giving the leaf a triangular cross section.
long leaves with with high central rib 
triangle cross section 
The flowers look like white bluebells, except for the green line down each petal
Not a Horticulturist 
Interesting, but you lost me at ‘invasive, self-seeding and hardy’. 😁
That seems to describe most of my garden – grape hyacinths, snowdrops, stinking irises, forget-me-nots, mint… Maybe I should skip this one.
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Well, it will take over if not contained, but… the fun challenge is to EAT it into submission. It’s mild so it’s easy to use as a vegetable. I just had to look up ‘stinking iris’… does it really smell beefy?
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We’ve just inherited a garden full of it. We are desperately trying to cut most of it back before it flowers and seeds itself. We would dig it all up as the topsoil seems to have been eroded in many places by it, and it has smothered most other spring flowers that apparently used to be here. But we would need to replace a lot of topsoil and it’s hard to dispose of properly. We are going for the management approach, which will take a few years. It’s hopeless trying to dig it up in the dormant season, so many tiny white bulbs. Oh, and the whole street seems to be affected. Basically, I’m saying IT IS INCREDIBLY INVASIVE, and I would not recommend ever planting it in a garden!
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Oh no Emma… sorry to hear it has been so troublesome for you and it is sad that it wasn’t a choice that you were given. This is a testament to how well it grows and spreads. Thank you Emma for highlighting just how it invasive it is. It’s one that you definitely MUST contain should you choose to grow it. We do love eating it and we will happily eat it into submission. We’ve discovered that wild garlic spreads very easily too but that has a shorter season. If in doubt stick to foraging for it… but be careful with identification if you do.
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Now I’m excited! I walked past our local church the other day and was delighted by the sight of some lovely white flowers that were identical to these. I spent ages searching the internet trying to identify them. Now i I read this and it turns out that they’re edible. Awesome!!!
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Not only edible… but yummy. They probably wouldn’t mind you taking a few leaves, flowers or seed pods to taste. Just make sure it’s not where any animals do their business. If you keep an eye on them and see when the seed pods ripen you could take some seeds. They’re so invasive, you’d probably be doing them a favour. If it feels wrong you could always ask permission… or after lockdown I could send you something.
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Good afternoon, may I ask where to buy some seeds for this Three Cornered Leek? It is the same kind of plant which some Chinese would cover it up to get the sweet yellow tender shoots by depriving the plant of sun light? Thank you for your time.
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Hi Mimi, you might be able to get seeds online. You can look for it using the scientific name – allium triquetrum. Because it is deemed a weed and can take over a garden there aren’t many sellers. Just FYI in the UK it is considered illegal to plant it in public spaces because it is invasive. It’s not the same plant as the ones that the Chinese cover. That is called garlic /Chinese chives – allium tuberosum. There are plenty of seeds available online for those and those are not invasive. The Chinese chives do well in warm weather and the three cornered leeks grow well when it is still cold. I grow both in the same patch so that I have oniony/garlicky greens available all year round. Hope this helps.
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I have had them in my garden for years. Spend my life digging them up. Recently I have taken to eating the flowers and stalks. So I am now more tolerant. You do have to keep them under control or you will end up with a garden which only has three cornered garlic in it.
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Thanks Jane – definitely worth a warning. Funnily I’ve gone a bit the other way. I was absolutely delighted with them and wanted them to overtake my garden. I figured I would eat them into submission but I’ve recently seen a few places – parks and coastal areas that have been overtaken by them and you’re right. Once they run rampant you’re scuppered. I’m now going to dig my little patch out of the back garden and only have them in the front which is bordered by paving so they have nowhere to go. I wouldn’t like them to spread to my neighbours in the back. I may never be forgiven.
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Thought I saw an absolutely massive white stretch of TCL, at the churchyard today, when passing by many bluebells there. I plucked and smelt it. Noting its lovely spring onion fragrance and triangular stem, I told my carer: This is TCL. But when I got home and saw your pictures, I realised they weren’t. They had bulbils; yours don’t.
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Hi Tess
The TCL does have flowers that turn into blobby bits that get heavy and when they reach the ground they root. So I guess they kinda are bulbils? Personally I think they look like peas sitting inside their disappearing petals.
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Ah no they were fever few garlic, those I saw on Wednesday.
Then the next morning on a walk in the forest, this time, I came across a TCL patch. This wild leek was unmistakable as each has that unique green line arising from the base of its petal and no bulbils this time. Feeling confident, I plucked 20 short stems & made an omelette. They were delicious!
Now having tasted them, I can’t get why people complain about them being a nuisance, as they taste just great. I wouldn’t deliberately grow them in my garden though, so as not to frighten the neighbours.
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Thanks Tess
I’m going to have to look up fever few garlic.
That is why I love them. They grow so well and are delicious. However, I have seen the local park and allotments just blanketed in them and they’re really hard to completely remove. So I do also get why someone would despise them too.
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Sorry, typo error, the ones I saw on my Tuesday (not Wednesday) walk was fever few which I didn’t pick & the ones I spotted on Thursday was TCL which were yummy!
On a different note, talking about invasive plants, they do amaze.
My young son and I had planted some sunchokes (just 3) with an unsuccessful, pathetic harvest from a giant deep pot even though 9 robust-looking plants emerged with lovely flowers. And we thought that (nil-harvest) was the end of the deep-pot story. This spring (now over 20 Jerusalem artichoke) plugs have emerged out of pure soil, out of nothing! Where did they come from? We were sure we dug and dug and searched and searched. No tubers. We felt sure there was nearly no-harvest back at Christmas! How odd to be the only people who failed at growing a well known invasive in a pot. But as JAs are well known as the incurable optimistic invasive they are, they are back – with a vengeance. 🙂 I’m wondering whether to plant them in the difficult spot under the massive bully-sycamore tree where nothing else grows in thirsty, shaded clay, shall I? Hmm, 3 to 9 to 23, what next?
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LOL. Yes. They do have a funny way of making their way back. I always worry I’ve dug everything up and keep a tuber to grow but sure enough every year there’s about a dozen little Jerusalem artichoke shoots in my water tank planter.
You could try them in a really hostile spot but that might also mean harvesting is hard and the tubers get broken up when you do. Let me know what happens.
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No, no. It isn’t a hostile spot. It’s the only (sufficient space) spot left! I will let you know what happens next year. 🙂
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Ah. Understood. Good luck. Looking forward to hearing.
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As you once said, space is a ‘growing’ problem. 😂
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Just to add a correction: the weedy clumpy ones my neighbour gave me which tasted like delicious sweet chives (when slightly wilted by frying) are three-cornered leeks, which were also escapees in the forest, whereas the en masse ones in the church yard, I now know, are called few-flowered leek or allium paradoxum.
They were confusing as both have triangular stems but as their name showed, the latter (FF leeks) have very few flowers, whereas the former (TC leeks) have a distinct green line inside each flower and these have plenty of bell-like flowers. I didn’t forage the FF leeks in our parish church as I don’t like the look of them: they had bulbils all over them. Also, I didn’t like the fact that they had to a large extent displaced the native wild garlic (ransoms) that used to be there. What thugs. Maybe we should try to stop them, but boy the bulbils look yucky.
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Ooo… Thanks Tess. Something new for me to look up. Hmm… one of the best ways to control it would be to eat it and get everyone else to eat it. That’s how we keep the three cornered leek in our garden from going insane – especially if we eat all of the flowers. Maybe the bulbils could be used like garlic?
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