Supermarkets have gone "greener", but still need to do more to help customers reduce their environmental impact, according to a report.
Some stores like Sainsbury's have plastic bag recycling points
Sainsbury's, Waitrose and M&S were given a B grade for their efforts in a survey of eight big food retailers by the National Consumer Council (NCC).
Tesco and Asda were awarded a C grade. while Morrisons, Somerfield and the Co-Op received D grades.
The NCC said chains must do more to cut plastic bag use and recycle packaging.
They were also urged to increase the amount of organic and locally-sourced food on their shelves.
Chair of the NCC Larry Whitty said: "NCC's research has spotted important signs of progress right across the market, with all stores now beginning to embrace sustainability.
"But much remains to be done if supermarkets are to become truly green grocers."
Tesco was said to be showing "potential", and along with Somerfield was said to be leading the way in offering customers incentives to bring back used carrier bags.
The Co-op and M&S, on the other hand, were the only supermarkets not to have plastic bag recycling points in stores.
The NCC said all retailers must do more to cut plastic bag use, for example by removing bags altogether from checkouts.
M&S and Sainsbury's were found to have done the most to use recycled and Forest Stewardship Council-certified content in packaging, but overall the NCC was "disappointed" by progress in this area.
It said most stores offered "very little choice" of organic produce, and some actually slipped in their ratings for stocking and promoting in-season vegetables and organic fresh produce.
While there were "some improvements" in the availability of sustainably-sourced fish in all chains, but there was little progress in promoting these products.
Asda's "Smart Price" value fish fingers were named the consumer group's green product of the year because they are made from sustainably-sourced pollock.
Andy Bond, Asda chief executive officer, said the chain was "delighted", adding: "Customers tell us they want to do the right thing, but don't want to pay more for the privilege."
Tesco offered the cheapest energy-efficient light bulbs at the time of the survey, but was "let down by a lack of information in store and on helplines", the NCC said.
The "Green Grocers?" report was based on a survey carried out in April.