Looking back at the Japanese Knotweed Symposium

Knotweed on a pedestal

We look back at a two-day gathering with researchers, designers, and artists, which aimed to explore Japanese knotweed and our relationship with this contested plant. Japanese knotweed was put on a pedestal, and the positive tone of this event was surprising as well as refreshing. It made us realize that knotweed and our response to knotweed gives ground to much broader questions about research, circularity, and our understanding and definition of nature in the city. A big thank you to all the speakers and the guests for your insightful contributions!



Symposium slide -

Looking back at the Japanese knotweed Symposium

Apart from the exciting new insights that came as a result of the symposium, we also found that collaboration and interaction between different discpilines can be a great stepping stone for a more holistic approach to dealing with knotweed. It was a great invitation to share insights and work together. In this article you can find the presentations of all the speakers that contributed to the symposium as well as other useful links. On top of that you can find the recordings of the whole event in case you missed out on (part of) the program. 

Presentations of the various speakers

Did you miss out on some of the presentations? Was there information that particularly excited you? Or did you miss the chance to take a picture of that one beautiful slide? Here you can access all the presentation that were shown during the symposium. Enjoy!

Friday 14th of April

Block 1: Introducing the Invasive Exotic

Get to know the invasive exotic, as a newcomer, as a threat or as a part of our environment.

Johan van Valkenburg (NVWA)

Johan van Valkenburg is a Senior Scientist at the Netherlands Institute for Vectors, Invasive plants and Plant health (NIVIP) of the NVWA, leading research projects relating to invasive non-native plants. In his talk he explored how decisions regarding the management and control of 'invasive exotics' come to be, and in what way knowledge is communicated to various actors.


Johan van Valkenburg - Japanese Knotweed Symposium Day 1

Download his presentation here: J. van Valkenburg - Japanese Knotweed Festival

Remko Andeweg (Bureau Stadsnatuur)

Remko Andeweg works as an urban botanist at Bureau Stadsnatuur, which is a part of the Natural History Museum Rotterdam. He will talk about his observed shift in the urgency to control Japanese knotweed, and he touched on the plethora of techniques that are used to control or exterminate the plant.


Remko Andeweg - Japanese Knotweed Symposium Day1 -

Download his presentation here: R. Andeweg - JKW as unfriendly stranger 

Sus Willems (Duizendknopen ontward)

Sus Willems worked for the Environmental department of the Flemish government, and recently started  an ecological consultancy company 'Duizendknopen Ontward'. In his presentation he presented cheap and relaxed ecological control methods that are focused on keeping the plant in check by introducing other (plant) species.


14-04-2023 Sus Willems geeft een presentatie tijdens het Japanse Duizendknoop Symposium - Lief je Gast - Japanse Duizendknoop Symposium Het Japanse duizendknoop symposium, dat plaatsvond op 14 April 2023, is een bijeenkomst met onderzoekers, ontwerpers en kunstenaars, waarin de Japanse duizendknoop en onze omgang met deze plant werd onderzocht. De Japanse Duizendknoop is een 'invasieve exoot' die mag worden uitgeroeid. We zoeken juist naar manieren om met deze plant samen te leven. Zijn er ook andere mogelijkheden dan een buitenstaander uitroeien?

Download his presentation here: S. Willems - My Exotic Neighbourhood

Block 2: Responding to Japanese Knotweed

How can we respond to Japanese knotweed? A collection of diverse and innovative approaches, both philosophical and practical.

Anke Wijnja (The Nature Connection)

Anke Wijnja is a forager, nature coach, mindfulness trainer, bushcrafter and craftswoman. She works from sustainable incubator 'De Ceuvel' in Amsterdam Noord. In her work she explores why some plants are celebrated and other plants are contested. She shined new light on Japanese knotweed by diving deeper into its culinary, medicinal, and nutritional properties. 


Anke Wijnja - Japanese Knotweed Symposium Day1 -

Download her presentation here: A. Wijnja - Wildpicking

Gjalt Jan Feersma Hoekstra (Agriton)

Gjalt Jan Feersma Hoekstra (Agriton Group) has been active as a consultant for sustainable solutions in Agriculture for over a decade. His Dutch company Agriton Group, has brought the Bokashi concept to the Netherlands. In his talk he described the Bokashi concept, and helped us make an informed decision whether Japanese knotweed 'waste' can be processed with Bokashi into a valuable product.


Gjalt Jan Feersma Hoekstra - Japanese Knotweed Symposium Day1 -

Presentation not available.

Norbert Peeters (Universiteit Leiden)

Norbert Peeters is a botanical philosopher, writer, and PhD-student at Leiden University. He took us on the historical journey of knotweed in the Netherlands, and he explored the sudden shift in the way Japanese knotweed is publically valued. 


Norbert Peeters - Japanese Knotweed Symposium Day1 -

Download his presentation here: N. Peeters - How knotweed came to be loved and hated

Janny Vos (CABI)

Janny Vos manages a Dutch office of the Centre for Agriculture and Bioscience International (CABI). CABI’s scientists have carried out extensive research into the biocontrol potential of an insect and a fungal pathogen that target knotweed. Janny Vos is involved in this research, and gave us an insight into their progress.


Janny Vos (CABI) Japanese Knotweed Symposium -

Download her presentation here: J. Vos - Bio Control of Japanese Knotweed

Jaike Bijleveld (Amsterdam Municipality)

Jaike Bijleveld is in charge of controlling knotweed in Amsterdam on behalf of the municipality. She will talk about their strategy, concerns, and current developments. Is there space to celebrate this persistent plant?


Jaike Bijleveld Japanese Knotweed Symposium Day1 -

Download her presentation here: J. Bijleveld - Japanese Knotweed Festival


The first day of the symposium was rounded off by a panel discussion led by Nout Verhoeven, director at the engineering office of the Amsterdam municipality. In a colourful discussion Johan van Valkenburg, Sus Willems, Norbert Peeters, Janny Vos, Jaike Bijleveld and Debra Solomon explained what they took from the day and gave their final take on how we should interact with knotweed. By uniting these different perspectives, we invited everyone to ask themselves the same question.


Panel Japanese Knotweed Symposium Day1 -

Saturday 15th of April

Block 3: Growing Companionship

Let's talk about knotweed in our built environment and how we can inhabit the city together. 

Mas Jansma (UVA)

Mas Jansma is a biology student at UVA. He performed a research project centering around the genetics of the knotweed populations in Amsterdam. He explained how he relates to the plant as a researcher, and showed that we may not know 'our neighbour' as well as we thought.


Mas Jansma (UVA) - Speaking at the first Japanese Knotweed symposium at Mediamatic Justin Knelange

With: Mas Jansma

Download his presentation here: M. Jansma - Phylogenetic relations of knotweeds in Amsterdam

Edwin Keijsers (Wageningen University & Research)

Edwin Keijsers has been working as a researcher at Wageningen Food & Biobased Research for the last 27 years, and is involved with the European project CityLoops. His work revolves around extracting and processing natural fibres for optimal use in circular industrial processes. During this symposium, he explained how Japanese knotweed could be used to replace non-renewable materials.


Edwin Keijsers (Wageningen university & Research) - Justin Knelange

Download his presentation here: E. Keijsers - Knotweed Festival

Gaja Mežnarić Osole, Danica Sretenović & Sebastjan Kovač (Krater)

Krater is a production space for a variety of practices such as papermaking, woodwork and myco-design located near the city centre of Ljubljana. Taking the regenerative capacities of pioneering species as its inspiration, Krater is set to produce environmentally conscious materials, practices and alliances.


Krater (Gaja Mežnarić Osole, Danica Sretenović & Sebastjan Kovač) - Justin Knelange

Block 4: Art/Design research

Artists and designers look at the ways at which we can work and live with Japanse knotweed.

Raphael Jaschko (Neo Flutes)

Raphael Jaschko is a musician and craftsman from East Bavaria, Germany. He talked about the difficulties and the beauty of crafting with knotweed, showed the different instruments that he has crafted, and delighted us with live flute performances.


Raphael Jaschko (Neo Flutes) - Justin Knelange

With: Neo Flutes

Download his presentation here: Neo Flutes - Japanese Knotweed Festival

Why Knot Design

Why Knot Design is set to turn a hated plant into a beloved product. They showed the beauty and potential of knotweed as a degradable and reusable material.


Marit (Why Knot Design) - Justin Knelange

Download her presentation here: Why Knot_ Japanese Knotweed Festival

Introduction Festival participants

Some of the artists presented their contribution to the Japanese knotweed symposium. We got to know them and their work during a short presentation round.

Uno Fujisawa & Takako Hamano


Uno Fujisawa & Takako Hamano (EatArt) - Justin Knelange

Download their presentation here: Uno Takako - Eat Art

Lucie Havel


Lucie Havel - Justin Knelange

With: Lucie Havel

Download her presentation here: L. Havel - Dyeing with knotweed

Pauline Wiersema


Pauline Wiersema - Justin Knelange

Download her presentation here: P. Wiersema - Duizendknoop Kookshow

Not in My Backyard

Niek & Kristof will took us on a walkthrough of their exhibition 'Not in My Backyard'. 


Niek Kosten & Kristof Vrancken (Not in my backyard!) - Justin Knelange

Download their presentation here: Not In My Backyard

Exhibitions opening

The second day of the symposium was closed off with a celebratory opening of the several exihibitions of the Japanese Knotweed festival. We got to know the artists behind the exhibitions and their relationship with Japanese knotweed.

Niek Kosten & Kristof Vrancken (Not in my backyard)


Niek Kosten & Kristof Vrancken (Not in my backyard) - Justin Knelange


Alaa Abu Asad (The Dog Chased its Tail To Bite it Off)


Alaa Abu Asad (The Dog Chased its Tail To Bite it Off) - Justin Knelange


Virgile Durando (Duizendknoop Mozaïek)


Virgile Durando - Justin Knelange

Download his presentation here: V. Durando - Symposium

Yoshinari Nikishi (Invasive Energy Harvesting: EROI Drink)


Yoshinari Nishiki (Invasive Energy Harvesting: EROI Drink) - Justin Knelange



JKF Symposium day 2 audience - Justin Knelange


Sponsors Japanese Knotweed Festival -


Recordings of the livestream