Should we possibly consume the long-lasting plant native to Japan?
Hackin' Gardens: Can Japanese Knotweed be Devoured Away?
...Or Is That Just a Load of Rubbish?
CULTURE - The Radio, Jun 13, 2025, 5:32 PM
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Japanese knotweed has become a persistent menace across Germany, choking out native flora and threatening the beauty of our gardens. Some resourceful souls have suggested a specialist culinary solution to the problem—considering the plant not just an invasive species, but a potential delicacy. But can we really munch our way to a knotweed-free landscape? We delve into the tangled world of this mysterious plant.
By Inka Zimmermann
Japanese knotweed, or Fallopia japonica, grows like a weed—quite literally! During its primary growing season, it can expand up to 10 to 30 centimeters per day. Environmental organizations class it as "highly competitive," meaning it dis posses a vast array of native plants, reducing the garden to its dominion alone. Not quite native to Europe, Japanese knotweed arrived here from East Asia in the early 19th century, an invasive stowaway in the pockets of the continent's earliest settlers.
Knotweed's Wild Ride in Leipzig
In Saxony, Saxony-Anhalt, and Thuringia, the species has been a long-established resident. Stefan Klotz, a plant ecologist at the Helmholtz Centre for Environmental Research - UFZ in Halle, notes that the floodplains of Leipzig provide the perfect habitat for the plant, along with the surrounding heathlands, landfills, and stream banks.
But climate change isn't exactly helping the cause: a warmer, wetter world is only likely to exacerbate the problem, as invasive species often thrive in such conditions.
The Great Knotweed Debate
Social media buzzes with suggestions of how to combat this tenacious invader. Some folks have proposed consuming the plant as a solution, arguing that if we eat enough knotweed, we can starve it out and prevent future spread. In theory, the idea isn't entirely absurd: young shoots are low in toxicity, and some even claim that a type of jam can be made from them, somewhat similar to rhubarb.
The Taste Test
Stefan Klotz, a knotweed enthusiast with a taste for adventure, has dabbled in these culinary creations himself. "I've tried knotweed jam," he recalls. "But, to be honest, I didn't find it very tasty." Still, perhaps our own personal palates aren't the best judges of its potential utility.
One thing is certain: munching on knotweed shoots isn't going to solve the problem of invasive spread. It's not a one-on-one fight. The plant reproduces primarily through its extensive root system, which can grow meters deep and wide, allowing for rapid colonization. Even if the entire above-ground portion of the plant were to be consumed, the root system would remain untouched and capable of producing new growth.
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Knotweed's Rhizome Wars
Manual removal of Japanese knotweed is possible, but laborious and time-consuming. The plant's problematic rhizome—basically an underground stem—play a significant role in its strong comeback potential. "If I mechanically break down the rhizomes into small pieces, for example, by chopping them, then the individual creeping sprouts can sprout again," explains Stefan Klotz. Regular mowing can help by reducing the nutrient supply to the rhizomes, but it's a long-term effort requiring diligence for many years.
Interestingly, the plant's earliest European introducers may not have been aware of its invasion-inducing capabilities. Originally, the knotweed was deliberately imported for its ornamental value, fodder, medicinal benefits, and for sustaining bee colonies during late-season blooms. It wasn't until the second half of the 20th century that the Japanese knotweed started to become a widespread problem in Europe.
Knotweed Controls: What Works?
Professional herbicide application is considered the most effective means of large-scale control. Smaller infestations can be tackled through manual removal, though this requires considerable effort and persistence, as the plant readily regenerates from tiny root fragments.
In Europe and Germany, the plant is now a protected species, and it cannot be planted without authorization under the Federal Nature Conservation Act. Some cities and municipalities are turning to electric shocks for the removal of the plant, hoping to "zap" it down to its rhizomes. The jury is still out on the effectiveness of this approach, but it's certainly an innovative idea!
Remember: eating Japanese knotweed is not only ineffective in controlling its spread, but it can also contaminate the soil, leading to new infestations nearby. It's best to stick to the edibles you know and leave this invasive species to be tackled by the experts.
Sources- [1] Wikipedia. (n.d.). Japanese Knotweed. Retrieved January 10, 2023, from https://en.wikipedia.org/wiki/Japanese_knotweed- [2] Royal Horticultural Society. (n.d.). Controlling Japanese knotweed. Retrieved January 10, 2023, from https://www.rhs.org.uk/advice/profile?PID=470- [3] Invasive Species Ireland. (n.d.). Japanese knotweed. Retrieved January 10, 2023, from https://invasivespeciesireland.com/japanese-knotweed/- [4] National Park Service. (2021, April 16). Control Japanese Knotweed. Retrieved January 10, 2023, from https://www.nps.gov/articles/control-japanese-knotweed.htm- [5] British Columbia Ministry of Forests, Lands, and Natural Resource Operations. (2021, December 9). Japanese Knotweed. Retrieved January 10, 2023, from https://www2.gov.bc.ca/gov/content/environment/pests-diseases/weeds-invasive-plants/japanese-knotweed- [6] Invasive Species Ireland. (n.d.). Identification and control. Retrieved January 10, 2023, from https://invasivespeciesireland.com/japanese-knotweed/id-and-control/
- In the realm of health-and-wellness, some individuals ponder whether consuming Japanese knotweed could potentially aid in managing the invasive species issue, given its low toxicity in young shoots and the possibility of making a jam similar to rhubarb.
- The field of environmental science and climate-change research suggests that as the world warms and becomes wetter, invasive species such as Japanese knotweed, which thrive in such conditions, are likely to proliferate more, posing significant challenges to the ecosystem and health-and-wellness of our gardens.
- Fitness-and-exercise enthusiasts might find it intriguing to know that although munching on knotweed shoots isn't a solution to preventing its spread, the activity of manually removing the invasive plant could contribute to maintaining our gardens and promoting overall wellness while engaging in physical exercise.
