Garden Centre Association (GCA) inspectors Alyson Haywood, Andy Campbell and Ian Boardman are standing down from their roles at the organisation this year.
Ms Haywood will be taking on an operational post with Van Hage, Mr Campbell wishes to spend less time away from home and more time with his family and Mr Boardman is going forward to work on other projects.
GCA chief executive Iain Wylie said: "We're really sorry to see these three widely respected industry experts go, but completely understand their individual decisions to step down at this stage and wish them all the very best with their new ventures.
"They have all been a pleasure to work with and an integral part of the organisation. They will be missed and I'd like to thank them for all their hard work and commitment."
Industry stalwart and GCA inspector Roger Crookes will continue in his role at the association.
Mr Wylie added: "We've begun the task to look for replacements and we're very happy to speak to people interested in the posts from all areas of the industry. Anyone keen to find out more about the role should contact me via email or phone at the GCA before we start the recruitment process in earnest so we can ensure they get full details sent out to them.
"We view this very much as an opportunity to re-fresh our team of GCA inspectors and we're seeing this as a positive situation moving forward, although of course we're very sad to see Alyson, Andy and Ian go."
GCA chairman Julian Winfield said: "The GCA appreciates the effort and contributions over the years from Alyson, Andy and Ian, and the inspection process has undoubtedly improved standards with our members."
Mr Campbell, who has been a part of the GCA inspection team for the past 12 years, added: "I would like to think that I have served the GCA members well during this time, supporting the members in improving retail disciplines and customer service standards as they develop their businesses.
"I have thoroughly enjoyed my time in this role and learnt a lot at the same time. I would like to thank the GCA for enabling me to participate in what I believe is a very powerful business improvement tool and wish them well for the future.
"My reasons for leaving are entirely personal. With a young teenage family, I wish to spend more time at home during these important years, recognising that before I know it they will be making their own way in life. This is not retirement, simply a re-balancing of home and work life."