The award recognises the RHS president's personal choice of the exhibits in the great pavilion.
The north Wales-based nursery exhibited its rare and unusual plants from Vietnam, Taiwan, Korea and Japan.
Co-owners Sue and Bleddyn Wynn-Jones cultivate new plants from seed they collect on expeditions to remote parts of Asia and Central America.
"We felt the time was right to exhibit at Chelsea," said Sue Wynn-Jones. "We've been in the industry for 20 years and are quite well known. Also, we've just started selling plants by mail order, so it's important to get our faces out there. People are excited about the display and we've had lots of interest. It's likely we'll be back next year."
Also having a good start as a first-time exhibitor was Kevock Garden Plants, which won a Silver-Gilt Flora award. The stand featured alpine, bog and woodland plants.
Co-owner David Rankin said: "I have just retired from my job at Edinburgh University, so this is the first year I have been free for Chelsea. It's a huge logistical operation moving everything down from Scotland. And coming so far we didn't know in advance what the stand would be like. Added to that we had problems with the hot weather, but we managed in the end."