The sale of the stake by AIM-listed TEG Group gives Parkwood full control of Verdia.
Parkwood Holdings is acquiring TEG Group's shares in Verdia Horticulture, a joint-venture company that was launched in 2007 to manufacture horticultural compost products.
The Verdia plant at Exeter, Devon, is part of a larger facility that is owned by Glendale Grounds Management. Parkwood said the parties believe the future of Verdia is best served as a wholly owned operation.
The cash consideration for the shares is £150,000. Working capital loans of £200,000 have been repaid to TEG.
In the year to December 2008, Verdia recorded a before-tax loss of £51,000.