Notcutts and Blue Diamond are believed to have been in contention for the seven-centre chain owned by French group Truffaut.
Truffaut, owned by Belgium-based Louis Delhaize, backed G&L founders Kenn and Jackie Lloyd in 1997 to expand from their original Cadbury centre.
They bought Endsleigh, Barnett Hill, Gardenlands, Melbicks, Percy Thrower's and Huntingdon over the next three years. Cadbury and Endsleigh were sold to La Salle Investment Management in 2006 for an estimated £30m and leased back.
The Lloyds have now retired. Neville Prest is managing director and Carol Paris is operations director. The centres are run from Bristol.
Quinton Edwards director Simon Quinton Smith commented that a purchase of G&L by someone else "will hopefully allow them to move into the next phase" after the sale and leasebacks in 2006.
"If Garden Centre Group is going to end up with quite a number of sale and leasebacks with the same landlord, and if some don't work anymore because the rents are too high, there is a logical progression to talk to the landlords and see what can be renegotiated."
GCG and G&L both declined to comment.