Dobbies chief executive James Barnes told the HTA Garden Futures conference that his 25-store chain had 53,977 products on its system, but 40 per cent of sales came from just 250 of them.
He said: "Our challenge is rationalisation - making choices for customers. There is customer confusion about a morass of products. This is about putting them into context."
He said garden centres could not keep adding "candles and supplier stands. They have got to have a reason for being there. This will mean rationalisation - it's what customers want. Sales per square foot are important."
Wholesaler Solus managing director Nick Davies said: "Choice has to be scaled down. The buzzword is category management. If we get it right the retailer will benefit from it. There needs to be willingness from retailers to simplify product ranges."
Scotts general manager Martin Breddy said it would not take much to run down 50,000 stock-keeping units to 30,000, which would result in "a nice, simple and cleaner offer". He added that Scotts surveys showed 45 per cent of customers who look at garden products do not buy and that was "woeful".
"The tyranny of choice is hard for shoppers to navigate their way through," he said. "The amount of inventory tied up in the supply chain makes for an inefficient system."
Cleeve Nursery owner Alan Down said: "We slimmed down dramatically four years ago to stock just the brand leader and alternative across the range and customers didn't notice. It meant far less work with fewer lines to order and manage. Before that, we stocked nine or 10 ways to kill a slug."
But Garden Industry Manufacturers' Association director Neil Gow said: "Dobbies does not have that many stores. This is still an industry led by independents and one of their great strengths is their variety. Too many stock-keeping units is caused by trying to carry too big a range that is too diluted with products beyond gardening."