Fonseca Terra Prima Organic Reserve Port is made from organic grapes. Historically, organic port is difficult to produce, partly because of problems with vine disease and partly due to a lack of nutrients in the soil, both of which require treatment or fertilisers.
For the last stage of the process the producer had to locate a specialist distiller with the ability to produce an organic fortifying spirit, which was then approved by the Port Wine Institute.
Terra Prima will be stocked by Sainsbury's from Monday (13 November), priced at £10.99.
A year ago Marks & Spencer was one of the first retailers to bring out an Organic Reserve Port, priced at £9.99. A spokeswoman said the port did well last Christmas. "Organic port is a niche market but we are looking to develop this," she said.