With plastic use under scrutiny and sustainability goals climbing higher on the agenda, a major research project by Wageningen University & Research is helping greenhouse growers make confident, science-based choices about plastics. The recently completed Circular Use of Plastics in Agriculture and Horticulture project offers practical results, including fully tested biodegradable grow bags and flower netting, that prove circular alternatives can match conventional materials in performance while vastly improving end-of-life outcomes.
"We wanted to get a grip on the central question: what is the most circular and sustainable choice for a plastic product used in agriculture or horticulture?" says Wouter Post of Wageningen Food & Biobased Research. "But we found that the answer is product- and cultivation-specific; it depends on the crop, the production system, and how the material is used and disposed of."
Two functional prototypes: grow bag and flower netting
In collaboration with seven industrial partners, the research team focused on seven different plastic products widely used in greenhouses during their three-year research. Grow bags and floriculture support netting were two personal highlights of Wouter out of these seven, as they showed exactly what they intended with the project. These were chosen not only for their prevalence but for the technical complexity involved in replacing them with biodegradable alternatives.
In the case of grow bags, currently made from polyethylene, the challenge lay in developing a biodegradable film that could retain sufficient mechanical strength, moisture resistance, and nutrient barrier properties during an entire tomato crop cycle. Researchers at Wageningen's Food & Biobased Research developed the material, fabricated prototypes, and tested physical properties such as stiffness, tensile strength, and water vapor permeability.
"We then transferred the materials to Wageningen Greenhouse Horticulture, where they were tested in live tomato production," Wouter shares. "And we showed that the tomato crop performed just as well in the biodegradable bag as it would in a conventional one."
After harvesting, the bags were subjected to industrial composting conditions. The material fully biodegrades, meeting EN 13432 standards, proving that circularity can be achieved without sacrificing performance.
The second case involved floriculture netting, particularly in freesia and fascia flowers, where netting is often left in the soil post-harvest and treated as waste. Current polypropylene or polyethylene netting does not degrade and can contribute to long-term soil contamination.
"With another of the seven products, grass turf netting, the requirement was even more complex: the material had to remain functional in soil for up to a year, but then biodegrade rapidly," Wouter explains. "We developed a net from biodegradable polymers, confirmed its strength and longevity in the crop cycle, and then validated that it degraded quickly once exposed to composting or moist soil microbial activity."
A dual-lab approach: material and cultivation science
The project was executed by two departments under Wageningen Research: Food & Biobased Research, which focused on developing and analyzing polymer materials, and Greenhouse Horticulture, which handled the cultivation trials.
Wouter explains how this collaboration worked in practice: "At our side, we developed new material formulations, processed them into demonstrators, and analyzed key properties like oxygen permeability, flexibility, and UV resistance. Then, we transferred the prototypes to our colleagues in the greenhouse labs."
There, the products underwent crop cycle trials - including plant performance, rooting behavior, irrigation compatibility, and handling during and after use. "Once cultivation was complete, the materials were sent back to us for end-of-life testing: compostability trials, biodegradation kinetics, and potential recyclability."
This workflow ensured a comprehensive assessment from the lab to the greenhouse to the waste stream.
A real-world decision tool for growers
While technical breakthroughs were key, the project also produced a decision-support tool for growers and suppliers. The tool, freely available online, uses a guided questionnaire to help users evaluate which plastic type or disposal route best fits their crop system and sustainability goals.
"We wanted to make our insights accessible, not just to our project partners but to the broader sector. That's why we developed this tool and a comprehensive report covering materials, disposal options, legal context, and tested case studies."
A role for legislation and market shifts
Post points out that some aspects of plastic use in agriculture are already being shaped by policy. "In areas like mulch films and coated fertilizers, legislation is now requiring biodegradable options. This project supports that direction, while also providing data and prototypes that could inform future regulatory developments."
Cost remains a consideration. Biodegradable materials currently cost more than conventional plastics due to lower production volumes and limited industrial-scale availability. However, Wouter believes the gap is narrowing.
"The price difference is shrinking. And if governments begin applying 'true pricing' to conventional plastics, accounting for environmental harm, then biodegradable options will become even more attractive."
With these real-world, tested results in hand, the project offers greenhouse growers proof that circular plastic solutions work.
"We've shown that it's technically feasible to move toward circular models in greenhouse production for a wide range of applications," Wouter concludes. "Now it's about scaling up and making sure growers have the tools and data they need to make informed decisions."
For more information:
Wageningen University & Research
www.wur.nl