The NGOs say a 2017 survey they ran found "consumers are crying out for peat-free products, yet a third of respondents couldn’t find peat-free compost clearly available.
They added that sales of peat are increasing despite the looming 2020 government ban.
Growing Media Association chairman Steve Harper said consumers would buy more peat-free if they wanted to and compared to 20 years ago, there is now much more peat-free on the market, with all garden centres stocking alternatives.
But he said GfK data showed sales had risen just a few percent over the last decade from around 13% to 16%. He said manufacturers had spent millions on peat reduction and the GMA had the buy-in of the NGOs into the peat reduction process, which has the next step of introducing a responsible sourcing "calculator" to work out the relative "costs" of materials used in growing media.
HTA horticulture head Raoul Curtis-Machin said the industry was committed to peat-reduction, that targets were voluntary, "the market has to decide" and that no one growing media material should be "demonised".
Harper said prices were a barrier for many consumers, with substitutes more expensive than peat. This is despite a 60-70% peat harvest caused by poor weather this year, which Harper says means prices must rise.
The Bord na Mona managing director added that production costs rise with labour costs, for example in Ireland costs are going up by 10.4% as the minimum wage increases are implemented.
Plastic bags have been hit by polymer (Platts) pricing rises, seeing record highs over the past 18 months and forecast to further increase during 2018. Environmental costs are on an upward trajectory with preparation for licencing under way in Ireland with new tougher targets on water quality.
Freight costs, which account for up to 30% of the cost of a bag of compost, are also rising. There is also ongoing uncertainty around Brexit, and weaker sterling is leaving a 22% difference between now and 2015 average Euro rate, and a 13% difference between current rate and the 10-year (0.80/1.25) Euro average.
Scotts general manager Sheila Hill said: "We have experienced rising costs throughout our business and expect more significant increases in key raw materials for 2018 trading year. Specifically, raw materials such as peat and plastic packaging costs will increase by double digits. This is a significant challenge on top of the impact of currency we have absorbed this season."
Harper added: "Manufacturers are finding themselves under increasing pressure, during a period where costs have risen significantly and millions of pounds have been poured into developing new products and new diluents to reduce the demand for peat."