The Growing Media Association (GMA) joined the initiative late last year, said BOPP technical chairman Wayne Brough.
"It [is] a practical alternative to ISO standards," he said. "BOPP is primarily a quality-management scheme laying down requirements for professionalism, records and third-party inspections."
Notcutts Garden Centre in Solihull held a training workshop for 17 GMA members. Westland Horticulture, Humax Horticulture and White Moss Horticulture have signed up to the scheme, which aims to im-prove transparency and uniformity.
Brough said: "The scheme was targeted at growers and ornamental packhouses, but with growing media on board we are going down the supply chain."
Brough, an ADAS ornamentals consultant, said BOPP planned to expand "up the supply chain" and involve local authorities and garden centres. He gave no timescales but said: "We are trying to get certification from raw producers right up to the final retailers."
HTA business development director Tim Briercliffe said BOPP certification would allow firms to demonstrate to customers quality of management control, health and safety and consistency.