Golden Acres Nurseries operations director Simon Edwards has decided to end the exhibition because he wants to expand the nursery's core bedding production.
Edwards said external factors had made no difference to his decision. He explained that the GAN show was a "reasonably profitable enterprise" but a "very small part of what we do".
"In the past five years we've concentrated more on core business and stopped growing nursery stock and propagating." He pointed out that the legacy was there if anyone wanted to take over the show, but it took up too much staff time.
He added that bedding was no good in polytunnels in January and February and he wanted to bring it into the glasshouses where GAN was held.
The neighbouring Southern Growers trade show was also thought to be under threat after organiser Monro South went into administration this month. But Roundstone Nurseries managing director Peter Cook said it would go ahead on 9 November at Roundstone Nurseries in West Sussex.
"We still intend to run Southern Growers. The date is provisionally in the diary and we're starting a marketing plan. With Monro South in administration, there is uncertainty there in terms of what is happening and we'll have to wait and see whether a buyer comes along.
"We think there is a need for a southern-based show and we will do whatever we can to run a show here, even if it is run entirely by Roundstone. The demise of GAN heightens that need."
GAN started in 1994 as a nursery open day. In 1998, 77 exhibitors occupied 150 stands and by 2010 there were 174 exhibitors occupying 235 stands.
Edwards said: "Those of us who worked to make this event what it is are immensely proud of what has been achieved and grateful for the support that all the exhibitors and visitors have shown us over the years." GAN had become the largest horticultural trade show in the south and the first of the year.