The trade body is running a survey at www.gima.org.uk/index.asp for exhibitors and retailers about the show, which has seen visitor numbers drop to 9,112 from 11,000 in 2011, 13,000 in 2010 and 24,530 in 2006.
GIMA director Neil Gow, who organised a summit for eight industry bodies to discuss the show last week, says the difference for 2013 for the 38-year-old show is that industry and trade associations are "pulling together to help, while in the past they have worked hard to pull in opposite directions".
Gow said it was a "red herring" to merge Glee with other shows or to move to a cheaper venue from Birmingham NEC because a majority want it to stay put.
Glee director Nick Davison says that without the pet audience following the end of Glee's partnership with PetIndex in 2012, visitor numbers were bound to be down. He said garden centre visitors were only seven per cent down on 2011.
Glendoick Garden Centre director Ken Cox said: "In common with many other garden centres we did not go to Glee this year for the first time in 20-plus years. It can't get any smaller. The crisis started a few years back when pets, furniture and plants all disappeared to have their own shows."
Alton Garden Centre director Andy Bunker said: "Glee has good and bad parts. We need to get it to be a specialist sundries show."