Styropack said B&Q's green claims for its new packaging could be undermined if they took into account the cost of importing coir from the Indian sub-continent.
Coletta and Tyson has produced the new bedding packs that rot where they are planted, replacing old polystyrene packs. The bedding packs use 96-99 per cent peat free compost, with a coir base.
B&Q responded by saying the move to APET and coir to replace polystyrene and peat "was driven by our commitment to improving the sustainability of our business."
BioRegional, a sustainability company, has told B&Q, APET and coir has a lower carbon footprint than peat and polystyrene.
B&Q bedding buyer Ben Smith said: "With easyGrow Teabag Technology we're able to offer bedding plants that make it easier to get planting by removing the APET tray and popping the plant, contained in the coir-filled teabag straight into the soil."