The annual awards attracted 400 guests and rewarded the best gardening products of the year.
Solus won the top Sword of Excellence prize for its Nortene Home Composter, while Honda won the marketing excellence prize for its live seed mailer.
But Westland UK sales manager Ken Evans, who failed to win anything for the top-selling new weedkiller Resolva, said: "Are these the green awards or the manufacturers' awards? GIMA needs to understand this is not a green award - it's commercial. Look at the categories they've awarded on - have they delivered revenue to garden centres, DIY stores or grocery outlets - that's what we're here for. There's no evidence of that in two or three categories. It's about commercial against gimmicky. The awards are politically correct at the moment."
Bayer marketing head Jane Lawler, who will be GIMA president in 2009, said: "How do we make the award winners genuinely those products that have done the best in the market in the season we're talking about? Presumably judging included carbon footprints and environmental soundness. That's important but they're not necessarily products that sold best, which would give retailers a better way to judge new products."
GIMA director Neil Gow said: "We have independent judges. GIMA has no influence over the judges."
He added: "Entrants are not asked to submit detailed sales figures. We rely on judges' knowledge of the products and, if they are retailers, how they sold through."
- For a full list of winners, see www.gima.org.uk/gimawards.htm.