Set in a spectacular position above the Menai Straits with Robert Stephenson's railway bridge on one hand and the mountains of Snowdonia lining the southern horizon, Plas Newydd enjoys a superb scenic backdrop to the delights of the garden. It enjoys a very mild climate due to the proximity of the Gulf Stream and thus a wealth of plants and trees rarely found in the British Isles. To the west of the house in the area known as the 'West Indies', lawns are bordered and broken by azaleas, hydrangeas, magnolia and scarlet embothrium, with hoherias and eucryphias flowering just after midsummer.

A dell, created from a small quarry, holds camellias, cherries, pieris and some rare trees. There is an arboretum known as 'Australasia' which was planted in 1981 and contains fast-growing trees and shrubs from the Southern Hemisphere. Finally, after enjoying the terraces near the house which have been replanted in recent years, the visitor can, in May, explore the rhododendron wood full of wild and exotic varieties.