Delivery from two national hubs, one in Cannock and one south of London, is believed to be on trial from this autumn.
Plants have been delivered direct to centres but will now have guaranteed delivery days.
GCG purchasing director Stephen Pitcher said: "We are currently reviewing all our supply chain options and looking at different ways to improve the delivery of plants and sundries to our customers."
Current distributor Solus said: "Solus is working with them on it and embracing the change. The depots are not central distribution hubs."
Growers and other suppliers are currently renegotiating GCG contracts. One grower told HW they had been asked to cut their prices by three per cent for the 2014 season.
HTA director general Carol Paris said: "Venture capitalists have seen a second successive difficult year and they expect a return on their money and if that hasn't happened will look at alternative ways of doing things."
- Tesco-owned Dobbies will not move to Tesco Headquarters in Cheshunt, Hertfordshire after shedding managing director James Barnes and employing Notcutts chief executive Andy King to replace him, say Dobbies. Industry sources had suggested it would cut costs if the Edinburgh-based group moved in with its parent, but Dobbies has denied that will happen.