He added: "They're at a very high level, so people can't complain. In my years as CEO of Home Depot there was always growth but now there's hardly any growth. But we're at a high level so people can't complain."
He said the UK was doing better than France and Germany though with low inflation and a mature market, Europe-wide sales are "flat".
Herbert said: "People are are buying less than ever but are buying better quality. The trend is for quality. Every company is trying to become a retail brand because of the internet."
He said that meant innovation and differentiation was required more than ever and smaller family-own companies in the garden centre industry were better at this than big corporations because they have less politics.