Seaweed plant pots for sustainable cultivation: turning seaweed waste into soil health and sustainable growth

Context Food systems face two urgent challenges: protecting and improving soil health, and reducing the environmental burden of agricultural waste. Plant pots and trays, widely used in agriculture and horticulture, are usually made from plastic. In Europe, more than 500 million containers are produced every year, contributing to landfill, incineration, and growing microplastic contamination in soils. This damages soil structure, microbial activity, and plant health. At the same time, new organic byproducts are emerging from the bioeconomy. In particular, seaweed is increasingly used to produce biostimulants and biofertilisers, and this process generates a fibrous residue. Although food-grade and nutrient-rich, this residue is often discarded as waste. The challenge Plastic pots are difficult to recycle and harmful for the environment, while alternatives such as peat or coir raise sustainability concerns due to ecological damage or reliance on imported fibres. Few current solutions can be planted directly into the ground while also improving soil health. There is therefore a need for low-cost, sustainable containers that both replace plastic and contribute positively to the soil. Our approach This project will develop biodegradable plant pots made directly from seaweed processing residue, with no chemical modification. The material can be moulded into sturdy, water-retaining pots suitable for germination and short-term cultivation. When planted into the soil, the pots naturally disintegrate, returning micronutrients and organic matter to the soil without leaving harmful residues. By using the whole seaweed byproduct rather than purified extracts, the process is simple, low-energy, and avoids synthetic binders. Aims and objectives Over six months, the project will: Test the durability, strength, biodegradability, and water-holding capacity of the pots under realistic conditions. Assess their effect on soil quality by monitoring nutrient release and biological changes during decomposition. Engage with growers, retailers, and consumers to understand user needs, willingness to adopt seaweed pots, and potential barriers. Analyse regulatory considerations for use in agriculture and horticulture. Explore the feasibility of scaling up production. Potential applications and benefits This innovation directly addresses two systemic problems: reliance on plastic in horticulture and the underuse of organic byproducts. By turning a seaweed residue into a practical product, it contributes to a more circular economy. Benefits include: Environmental: reducing plastic waste, avoiding peat extraction, and enriching soils. Agricultural: supporting plant health through the release of nutrients and organic matter. Economic: creating value from a low-value waste stream and aligning with market demand for sustainable growing products. Social: offering opportunities for localised production, especially in coastal regions, and supporting green jobs. In summary, this project proposes a simple but high-impact solution: transforming seaweed processing waste into biodegradable pots that both grow plants and regenerate soil. It supports national and international goals to reduce plastic use, protect soil health, and promote sustainable and circular food systems.