Award-winning designer Christine Parsons said she was astonished when a "highly respected and very experienced" designer complained to her about contractors.
"He wanted to know what it takes to make a contractor take a designer seriously," said the board member of the British Association of Landscape Industries.
"We will probably talk about this and set up a forum for registered designers to come together," she told last week's Glee garden industry trade show.
"My first thought was that it was a loaded question and then I thought such a question suggests they probably don't take designers seriously. That is something we need to explore professionally. I think it goes back to the situation where anyone can say they are a garden designer.
"There are a lot of courses out there and not every one is professionally accredited. Maybe a contractor will meet a designer who isn't perhaps very competent, so when the next one comes along they may think they will be rubbish.
"We need to work towards a situation where all garden design practices are registered and go through professional processes." Parsons' Sheffield firm Hallam Garden Design has won several awards.