The Outdoor Space Company was created eight years ago by David Richardson, who is planning to emigrate to Australia.
Bowden's garden design and build arm is headed by David Howard, former head gardener to HRH The Prince Of Wales, who has been working with Bowden since the beginning of the year.
Bowden owner Tim Penrose said: "This really is a natural extension to our business. We offer planting plans, and have already designed and built gardens with David Howard.
"The Outdoor Space Company has been run by David Richardson in a highly professional manner, and we are both proud and looking forward to building on its reputation.
"We will be working hard to ensure we pay great attention to detail in looking after David's clients as he sets off to start a new life in Australia."