The HTA figures emerged after the SEEDA-funded waste management pilot project report was publicised last week. The report identified the main types of waste generated and outlined ways for reducing, reusing and recycling.
Recent HTA studies showed gaining BS and ISO accreditations cost around £2,100 but savings of around £10,000 could be made on areas such as reducing landfill. And boasting environmental credentials could lead to sales increases of around £22,000.
HTA business project manager Alec Turnbull said: "Accreditations can lead to real financial benefits, not added costs.
"They can open opportunities for new market sectors for big suppliers and councils with high environmental standards."
WYG Environment Planning Transport carried out the report. Andrew Colquhoun, chairman of SEEDA's Horticulture Working Group, said businesses had to act now.
"They must manage different waste streams as landfill capacity is expected to run out by 2014 in the South East and landfill tax has increased," he said. "Segregation, segregation, segregation should be the mantra for horticultural businesses. Staff must be properly trained to recognise and sort waste to cut the amount going to landfill and save money. However, there are still hurdles to overcome, such as distances to the nearest specialist waste contractor."
The report suggested smaller businesses could pool waste for collection or share kit like balers for polythene waste. Growers could also ask suppliers to reduce packaging. Six nursery businesses and two garden centres in south-east England were studied.
The "general waste" stream, where recoverable or recyclable waste often ended up, made up the greatest proportion of waste generated on the sites studied. Much of this was likely to end up as landfill.