Wyevale Garden Centres online manager Darren Mogg will leave for a role outside the industry on March 31.
Remaining from the Nicholas Marshall era at head office include plant buyers Mark Sage and Nicky Roeber.
WGC is likely to restructure its online department.
Mogg was with the company for eight years.
Terra Firma bought WGC in March 2012, with Marshall being replaced by Kevin Bradshaw soon after. Buying director Steve Pitcher and horticulture head Tim Clapp have since joined B&Q, with many regional managers also leaving and WGC bringing in a host of new faces from across retail.