The 130-centre chain is expected to fetch around £300m.
Other interested parties are said to include private equity firms such as Bridgepoint and retailers including Wm Morrison.
Garden Centre Group chief executive Nicholas Marshall told Horticulture Week:
"There is a lot of interest in the company but I can’t go into detail about who is bidding and who isn’t at the moment because that would be unfair. The amount of interest is not surprising because we are unique and it’s a one-off opportunity. We’re all very optimistic because considering where the economy is and the international financial situation I think people see us as a very exciting asset."