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Here you can find answers to the questions we are most frequently asked about silphium, our silphie fibers and our silphie paper.


What is the silphium plant?

The silphium plant is cultivated in Germany as an energy crop. Silphium features a whole host of environmentally friendly properties and helps conserve existing ecosystems and biodiversity: it is perennial, has a long and late blooming period, requires hardly any fertilizers and pesticides, offers erosion and groundwater protection, helps ensure humus accumulation, and much more.

Where is it cultivated?

Primarily in Germany (roughly 10,500 hectares in 2022), although increasing numbers of silphium farmers in nearby countries – Italy, France, the Czech Republic, Slovakia, the Netherlands, Hungary and Austria – are using silphium as a source of sustainable bioenergy in their biogas plants.

Is the crop grown specifically for paper production?

The silphium plant is native to North America and so far has been cultivated as an energy crop, e.g. as an alternative to corn, on roughly 10,500 hectares (2022) of land in Germany. According to Germany’s Agency for Renewable Resources (FNR), a total of some 1.5 million hectares was used for energy crop cultivation in 2020, of which roughly 989,000 hectares for corn.

Previously, all parts of the silphium plant were used for biogas production. Now, separating the fibers prior to the biogas process make it possible to use the fibers as a raw material in paper production and offers an extra source of income for farmers and biogas operators. By doing so, we create cascading value for the plant. In expanding the area of cultivation, our focus is on areas that are already used to cultivate energy crops. We have no interest in repurposing other areas such as those used for food production.

Are EU agricultural subsidies available for silphium cultivation like there are for other cultivated areas?

Areas used to cultivate silphium can be classified as ecological focus areas (EFAs). In addition, some German states currently offer subsidies for cultivation.

Silphie fibers

How are the Silphie fibers produced?

Silphium is a perennial energy crop. It is harvested in the fall, chopped and preserved using an ensiling process to produce silage that can be used year-round as an input for treatment as fibrous material. Previously, the silphium plant was used in its entirety to generate energy. Now, by focusing on cascading use, we also enable the fibers to be used as a raw material. They are separated using a biothermal procedure before bioenergy production, and are processed into a new, regional and sustainable raw material. And with zero chemicals. Just a small amount of water and energy are used. The remaining parts of the plant are fed into the biogas plant as a fermentation substrate. Our silphie fibers are produced locally right next to biogas plants.

What can Silphie fibers be used for?

Silphie fibers are the raw material for fiber-based products. Additional treatment, such as milling, can adapt the fibers to customers’ specific needs and ensure optimal functionality in downstream processing. The areas of application include paper, fiber molding applications or natural fiber-reinforced plastics. Other uses are also conceivable.

Can silphie fibers be FSC® or PEFC-certified?

Silphie paper can be produced in combination with FSC-certified pulp, and as such is certified FSC Mix. Silphie fibers are not currently eligible for FSC or PEFC certification since these certifications are reserved exclusively for wood and paper products.

Silphie paper

Can it be called silphie “paper”?

In accordance with DIN 6730, paper is a flat material essentially comprising fibers, mostly of plant-based origin, that is formed by removing water from a fibrous suspension in a sieve. Since silphie fibers are fibers of plant-based origin and silphie paper is created using a paper-making machine, as previously described, we are well within our rights to speak of silphie “paper”.

What is silphie paper?

Silphie paper is made of silphie fibers and conventional pulp or recycled paper. Our paper grades have a silphie fiber content of 35%. The silphie fibers give the paper its brownish look and natural feel.

What grammages are available for silphie paper?

  • SilphiePaper: Basis weights from 60 gsm
  • SilphieLiner: Basis weights from 100 gsm
  • SilphieBoard: Basis weights between 200 – 450 gsm

What can Silphie paper be used for?

Silphie paper is suited to a wide range of different paper applications. While our primary focus is on packaging applications, particularly in direct contact with food, we also offer specific graphics applications. Our paper products are machine-smoothed and surface-treated, and feature good printability in standard printing processes (offset, flexo, screen and digital printing).

  • SilphiePaper: paper bags, labels, banderoles, sleeves
  • SilphieLiner: corrugated material, liner for corrugated cardboard production, fruit and vegetable trays
  • SilphieBoard: folding boxes, banderoles, displays

Is silphie paper FSC-certified?

We offer paper products featuring 35% silphie fibers. Following successful FSC® certification, our paper products use FSC-certified pulp.

Can silphie paper be used for printing?

Silphie paper products are machine-smoothed, surface-treated and feature good printability in standard printing processes (offset, flexo, screen and digital printing).

Can silphie paper be bleached to make the surface lighter?

Bleaching is possible in principle; however, it would require the use of chemicals that we have previously avoided. Nevertheless, our R&D activities focus in part at examining possibilities to bleach silphie paper.

Is the paper vegan?

Since we refrain from using animal-based products in all of our raw materials and supplies, we can designate our entire product range (SilphiePaper/SilphieLiner/SilphieBoard) as vegan.

Is silphie paper recyclable?

Silphie paper can be recycled just like conventional paper. You can dispose of it in the waste paper stream like you normally would.


Would you like to find out more about OutNature and its products? Just ask us!