The Cornwall-based young plant supplier is one of nine European growers using the Proven Winners Europe branding to promote their products.
Harnett said: "We should find out who the consumer is, though our immediate customer is the grower."
He said that in the US, where Proven Winners originated, it has become a strong consumer brand. "The website there received 2.4 million unique visitors last year."
Harnett said it is more difficult to create the consumer brand in the European marketplace because there is resistance. "A lot of larger businesses - the sheds and multiples - want to promote their own brands. We are concentrating on getting good new plants through and producing quality plants at a good price."
The growers in the Proven Winners Europe group pool knowledge about propagation, distribution and marketing with the aim of promoting "outstanding, innovative plant varieties emerging from some of the world's finest plant breeders", said Harnett.