Foraged Food Friday: Japanese Knotweed

Japanese knotweed is a highly invasive plant that comes up in early May, or thereabouts.

Young shoots of Japanese knotweed
(Fallopia* japonica or Polygonum cuspidatum)

A piece of rhizome the size of your fingernail can grow a new plant in just ten days and they're capable of growing through concrete. It's hardly surprising, then, that it's an offence in the UK (section 14(2) of the Wildlife and Countryside Act 1981) to "plant or otherwise cause to grow in the wild" Japanese knotweed (amongst others). Bearing in mind how easy it is to start a new plant, avoiding breaking this law requires some care. Put simply, any piece ypu cut off a plant must be destroyed carefully**. I choose eating and burning as two effective methods of destruction. Whatever you do, do NOT put offcuts on a compost heap.

When such an invasive plant turns out to be edible, I feel almost duty bound to eat it. That said, it took me a while to find some that I could harvest. The photo above was taken in my neighbour's garden and she wanted it left to grow leaves so she could apply glyphposate to them. I don't generally hold with using weedkiller but I have to concede that if you're going to make an exception for one plant, this is the one to make it for.

By the time I found another patch, about a week later, the shoots were no longer quite so tender. Nonetheless, I took the lot - a carrier bag full. The taste is reported to be just like rhubarb and as I couldn't see myself eating that much rhubarb crumble, I thought I'd have a go at chutney. I'd never made chutney before, but it's basically a mix of fruit and/or veg boiled up in vinegar and sugar - how hard can it be?

I started by chopping and stewing the knotweed - it was about three litres, chopped - with a pint of vinegar, lots of garlic (it was getting on a bit), a piece of fresh root ginger, and some more spices - cinnamon, cloves and juniper - tied in muslin. I then looked around the kitchen for other things I could throw in. One small onion... an apple that had been in the fruit bowl too long... a few ounces of muscovado sugar... a couple of half-jars of jam that just weren't getting eaten - rhubarb and ginger and apple and ginger (I prefer ginger in chutney than in jam) and a little 'Victorian chutney' that had also been lurking in the back of the fridge too long. I don't even know why it was in the fridge - it shouldn't need it. It was too sweet at that point, so I looked for something to balance that, and found half a head of iceberg lettuce in the fridge. It needed using up anyway, so that went in. Towards the end of cooking I decided that it needed more salt and that it was a very unappetising shade of light brown. I solved both of these with the addition of the remains of a jar of Marmite (a largeish tablespoonful).

Towards the end of cooking, the mixture stuck and burnt a bit. I stirred that in, which darkened it, so the marmite probably wasn't entirely necessary. In total, I got eight smallish jars of chutney out of all this.

Knotweed chutney

It's not the best chutney I've ever tasted, but it's certainly the sort of chutney flavour I was after and it's a lot better than the 'Victorian chutney' that had been lurking at the back of the fridge. I've been using it for all the usual things I use chutney for - eating with cheese and with plain things such as potato cakes and fritters, and stirring into sauces. It's pretty good. The only downside is that it does have some rather tough fibrous bits in, due to my not catching it early enough.

I don't suppose I'll need any more chutney for a few years yet, but I may think of another use for it next year. I might try making cordial, in which case the tough fibrous bits are less important, as I'd strain them out anyway.

---

* I was intrigued by this Latin name, so looked it up. Indeed, both the fallopian tubes and this genus of plants are named after the same person, the sixteenth century Italian anatomist, also professor of botany, Gabriele Falloppio.

** If we're being strictly legal about this, Japanese Knotweed is classified as controlled waste and therefore should only be disposed of at a licensed landfill site. I'm not quite sure what they do with it there, but I consider burning it to be more in keeping with the spirit of the law than any kind of landfill.

Also harvesting this week
Blusher mushrooms
Ceps
Oak bolete (some of each of these two have been dried, to store)
Sepia bolete
Scarletina boletes (these are the most fabulously colourful mushrooms!)
Hazelnuts, just a few as most are now gone
Parsnips
Evening primrose roots
French beans
Nettles
Mint
Rosemary
Bay
Sloes, for wine (we haven't quite reached the first frost yet, but it's mighty chilly and I know other people have been harvesting them, so I didn't want to leave it any longer in case I missed out)

Also eating
Crab apple and rowan jelly
Plain crab apple jelly
Bramble jelly
Lacto-fermented courgettes
Courgette puree (from freezer)
Tomatoes

Also drinking
Blackcurrant cordial
Sloe wine
Heather ale
Dandelion and honeysuckle ale
Beer with actual hops

Foraged food challenge summary page here.