Japanese knotweed material

Why Knot Design

The Japanese Knotweed is an invasive species that causes a major problem in the
Netherlands. It spreads quickly and leaves a trail of destruction to public spaces and our
biodiversity. The plant is currently being incinerated, which releases a lot of CO2 emissions.
To prevent this and spread awareness, Why Knot uses the Japanese knotweed to make

interior products. The material is strong, light and visually unique because the fibers are
used in various ways. In the process, sustainability is a big focus point (e.g. dry process and
no harmful additives) and the option to reuse or biodegrade it, therefore it contributes to a
circular economy.

Made of

98% of the material is a blend of Japanese knotweed originated from Rotterdam. A 100%
biobased binder is added to strengthen the material and increase the natural qualities of
the plantsfibers.

Production proces

The Japanese knotweed is harvested 2-3 times a year by a contractor on behalf of
municipalities and water boards. Why Knot is currently working with knotweed from
After pruning, the knotweed is immediately processed into usable fibers and will dry out in
the shredding process.
The fibers are delivered to Why Knot, which processes them into products through material
blends, binders and pressing. The production process takes ± 2 hours.
The products are personalized, making it clear where the material comes from, which
spreads awareness about the invasive species.
When the product has been used, it can be returned so that it can be processed into a new
product. It can also be put in the soil to biodegrade, which enriches the soil and there is no
risk of the knotweed growing back.


The Japanese knotweed material will be used as indoor design products. This way,
companies can take the first step towards circular offices or workplaces.

Environmental impact

Every year, 1,728,000 kg of CO2 is emitted by burning Japanese knotweed in the
Netherlands, which can be mitigated by using it as products.
No water is used in the process and a minimal amount of energy, giving it a small footprint.
CO2 is stored in the Japanese knotweed and thus also in the material/products.
No harmful substances such as formaldehyde are used.
When the product is used, the raw material can be reused for a new product. The material
can biodegrade completely and there is no risk of Japanese knotweed growing back.

Also nice!

Many indoor materials contain substances that are harmful to your health, such as
formaldehyde. Using knotweed products will greatly contribute to more healthy working
environments, because it is 100% biobased and not harmful to people and climate. In
addition, each product has its own unique look and feel due to the different fibers and the
time of harvesting. This ensures that everyone has a unique product to take care of.

Growth opportunities

Why Knot’s goal is to process all major invasive plant species in the Netherlands as
sustainable products so that it is no longer seen as ‘waste’ but as a usable raw materials.
This makes that we will make more use of the plants that grow locally and in this way
collaborate better with nature.