I am excited and dismayed to announce I finally found a patch of Japanese knotweed near me. Luckily not “near” enough I have to fear imminent invasion. On the other hand, the more I learn about how knotweed spreads, the less safe I think we all are.
Best of all (if there can be an upside to finding a highly invasive plant), I found it just in time to foraging the spring shoots, which are the edible parts of this ferocious weed. The location isn’t perfect for foraging, a little too close to a busy country road for my tastes. But I will take what I can get since this is reported to be a tasty wild edible … and do my part to help control its spread!
(Not really – based on the size of the infestation, there’s no way I could physically eat enough knotweed shoots to make a dent in its inexorable march into the countryside.)
The scientific name for this plant is either Reynoutria japonica, Fallopia japonica, Pleuropterus zuccarinii, or Polygonum cuspidatum – I have to admit this situation baffles me. Whichever name you give it, Japanese knotweed is one of the most invasive weeds on the entire planet.
The previous year’s dead stalks mark this plant’s location in the winter. The stalks are segmented like bamboo, hollow, and reddish in color.
Japanese knotweed was originally introduced into Europe and the United States as an ornamental for landscaping. In the United Kingdom in particular, this weed has caused enormous amounts of damage. Its roots find their way into small cracks in asphalt, rocks, waterworks, and foundations; then they expand, causing the cracks to worsen. Almost impossible to kill, even a small discarded chunk of the root can grow into a whole new infestation. Which means digging up the plant in an effort to kill it can actually contribute to its spread!
Once the shoots breach the soil in the spring – the first week of April for this patch – they grow very quickly. Some sources say they can grow as fast as four inches a day during the peak of its growing season in the summer!
The spring shoots are best harvested when still short – a foot high or less – tender, and unbranched. Discard the leafy tips and any leaves that may be forming. My plan is to leave these parts on the site, rather than bring home any part of this plant that won’t get eaten. You know, just to be on the safe side!
The older and larger shoots may need to be peeled before use. The shoots can be eaten raw or cooked. The flavor of knotweed is similar to rhubarb, although it is variously described as more sour, “earthier”, “greener”, or even “gamier” than rhubarb. Many sources recommend using any rhubarb recipe for knotweed but some foragers prefer recipes with more imagination and finesse. I am still debating what to do with my upcoming harvest. Because Japanese knotweed grows so fast, the foraging window is usually only a few weeks; time is of the essence.
As a bonus (I do always try to look for the positive side of things), Japanese knotweed shoots are apparently high in resveratrol, the antioxidant that allegedly makes wine healthy. The roots store the highest concentration – in fact, Japanese knotweed is even cultivated commercially for use in manufacturing resveratrol supplements. But I am not messing with the roots, thank you very much. I’ll stick to the shoots.