The walled garden is perhaps the centrepiece of Broughton Grange gardens and has been widely acclaimed. It was designed by leading landscape designer Tom Stuart-Smith in 2000, and consists of three-terraces contrasting the structure and form of topiary with wild, luxuriant herbaceous planting, whilst softly framing a beautiful rural backdrop. The design was conceived entirely in relation to the surrounding landscape, thus supporting superb views to distant natural features and buildings. Previous to its construction, the site was farmland. Hard garden features, such as the walls, gates and garden buildings, were designed by architect Ptolemy Dean and include a notable stepped stone wall on the western side. There are two sizable beech (Fagus sylvatica) tunnels on the eastern side of the garden and three pleached lime (Tilia x europea ‘Pallida’) squares to the west (one per terrace), which are underplanted with sweet box (Sarcococca confusa). The pleached lime structures frame a formal vista to the south, which incorporates hornbeam (Carpinus betulus) and yew (Taxus baccata) topiary specimens.
On the upper terrace, there is a Mediterranean climate walled border containing warm coloured perennials. There is a small vegetable and fruit growing area, which consists of a central circular fruit cage containing mainly soft fruit, surrounded by espalier apples. Four symmetrical sections within the garden are used for growing a variety of vegetables. Step over apple and pears are planted on two sides around the perimeter. The main planting has a prairie feel which consists of pencil yews (Taxus baccata ‘Fastigiata’) that punctuate low grasses such as tufted fescue Festuca amethystina, switch grass (Panicum virgatum ‘Shenandoah’) and African lovegrass (Eragrostis curvula). During summer, many spires of hooded, pale yellow flowers of Phlomis russeliana dominate the top terrace, accompanied by selected cultivars of Salvia nemorosa, Salvia x sylvestris and delicate purple Allium sphaerocephalon.