This area, close to the early 18th century Stainborough Castle, is one of the most interesting and complex areas of the Gardens. It comprises several different character areas, reflecting the sequential development of the site.

It was originally planted by William Wentworth in c.1755 as a setting for Stainborough Castle, with yews, sweet chestnuts, oaks and sycamores – British native or long-established – being the dominant plants, flanked by winding paths, some of which follow the line of what may be earlier defensive earthworks. Some of the paths, initially gravel, were retained by ornamental rubble (now reinstated in places).

In contrast to the 'formal' wilderness of the Union Jack Garden, this area conforms more to what we understand as a 'wilderness' today: somewhat wild, 'rude and irregular', where games are played with strong contrasts of light / dark, hide / reveal, reassurance / surprise. It was meant to bring 'wild' nature into the 'polite' environment of the fashionable stately home. This kind of wilderness – a dramatic move away from formal geometry in gardens, which had been derived from French style – was the first venture into a design philosophy that had its roots firmly in British soil. Thus, the most important plants in the wilderness are the native oaks, sweet chestnut, sycamores, yews and Scots pines which flank its winding paths.

In the 19th century, the idea of a rough wilderness was less enticing. Instead, the attractions of a 'Pleasure Ground' were more persuasive, suggesting an area of winding walks and shady glades, not rustic and dramatic, but more varied, colourful, even charming. It was in this period that we find the additions of more exotic plants at Wentworth, including two species of stately conifers, both introduced from North America in 1853: Thuja plicata, or 'Western red cedar', and the Sequioadendron giganteum, or 'Wellingtonia', one of the largest and longest-lived trees in the world and popularly named after the 'iron' Duke of Wellington, whose victory at the Battle of Waterloo, in 1815, against Napoleon, was thus commemorated. Collections of plants from the widening areas of influence and empire were important features of this period.

The late 19th / early 20th centuries century saw the culmination of this enthusiasm for exotic plants, with a focus on the introduction of many rhododendrons, including selections from the newly-developed hardy hybrids.

Through much of the rest of the 20th century, gardeners built on this tradition of introducing plants that owed their origins to far-flung parts of the world and, by the end of the 20th century, species Rhododendron, x williamsii Camellia and Magnolia were the three National Collections for which the Gardens became famous. In the winter of 2005/6, hundreds of rhododendrons were transplanted from elsewhere in the Gardens and now the species plants, gathered beneath the banners of the great collectors – including Joseph Hooker, George Forrest, Edward Wilson and Frank Kingdon Ward – represent one of the glories of the Gardens.