Bedding grower Doug Bradbrook, who runs Ravensworth Nurseries in Richmond, Yorkshire, was presented with the Harlow Carr medal by Roy Lancaster at the RHS Hampton Court Palace Flower Show.
The accolade was awarded for his "ongoing contribution to the bedding plant industry" in the north of England.
He said: "It's something you don't expect. They only give one or two a year and it was a nice night, even though it was pouring down outside, with thunder and lightning. It's good to see horticulturists getting awards. I think of them as going to garden writers normally. It is a bit of a boost for the bedding industry."
Bradbrook set up the business with his brother-in-law in 1963 and has specialised in producing bedding since he switched from growing tomatoes and lettuces due to increased competition and heating costs.
He said "times are tough" for growers, and have been for the past two years because of the effect of variable weather conditions on UK trade. "But we are able to avoid problems with fuel prices because we have our biomass boiler, which means we are carbon neutral," he said. "It allows us to continue growing poinsettias, which are an energy-hungry crop."