In 2002, PW Plants won the Tudor Rose for best in show at Hampton Court and in 1997/98 it won the RHS Lawrence Medal for best exhibit of the season. It has won 47 RHS gold medals.
Whittaker will continue working for Bowden as a consultant, just as Martin Rickard has done since Bowden bought Rickards Ferns in 2011.
Bowden is making a move into wholesale, selling mixed trolleys of ferns, hostas and grasses to garden centres and nurseries. The firm will exhibit at the Four Oaks Trade Show on 3-4 September.
Owner Tim Penrose said: "If we do 120 trolleys in our first year, I'll be delighted. When I've gone to garden centres and seen sad hostas on the floor ravaged by slugs, it's no wonder they don't sell."
He said two or three company representatives will "pop in from time to time" to check on the plants at the garden centres and retail nurseries he hopes to supply.
Plants will be branded and include Devon-based Bowden's royal warrant.