Sinclair managing director Peter Rush says growing media suppliers need to find better consistency in their products than in 2013 to keep the faith of gardeners.
He said: "There's no doubt we observed there were consistencies in blends. We saw some differences in products we got hold of.
Consistency varied through the year. Ultimately that is one of the big challenges for the industry. Consumers want consistency and good quality on a consistent basis."
Recent Gardening Which trials found several peat-free and peat-reduced seed composts performed badly.
Rush said peat-based mixes did better but because there was a peat shortage in 2013 some blends were not as they had been in 2012.
But in 2014, after a good harvest in 2013 "suppliers are using peat in greater percentages basically to bring costs down and enhance consistency of the quality of products."
Sinclair released results last week showing a loss in 2013 linked to the poor weather gardening year.