Rosier SA, a subsidiary of Borealis AG, specializes in the production and... Rosier SA, a subsidiary of Borealis AG, specializes in the production and distribution of mineral-based fertilizers. Its operations primarily serve the markets of Belgium and the Netherlands, offering a diverse product line that includes granular, liquid, and water-soluble formulations. The company, initially founded in 1880, was formerly known as S.A. Engrais Rosier before rebranding to Rosier SA in 2001, and is headquartered in Frasnes-lez-Anvaing, Belgium.