Media and communciations commitee members Tony Lane of AM Lane Ltd and Patrick Stileman of Patrick Stileman Ltd were selling books, running an identity quiz and giving out information to the 160,000 visitors to the RHS show.
Stileman said: "There's a lot of pretty bad work that goes on. People can come to the AA and get information about how to do it properly.
He added: "I think poor work by rogue traders is more prevalent, possibly because of the recession. It's very easy for people to pick up a chainsaw and get a van and go out and work. I've heard a lot of stories about people having trees devastated totally unnecessarily when there was no need to prune them. People think trees need pruning on a regular basis but often it only needs doing as a last resort."
Lane said: "In economically difficult times people want to find something that gives them an extra edge over their competitors. If they think being approved contractors is it, all the good for them."