The Peat Terrace Garden Garden is probably the UK's largest example of an unusual Victorian concept of peat brick terracing designed to subtlety change the pH of the natural soil to enable ericaceous planting. This partly wooded area of the garden was first constructed in 2006. The second larger phase of construction from 2017 to 2019 was carried out using peat bricks sourced from eastern Europe. The garden can be accessed from the Fountain Garden to the north, the Long Borders to the west and the Spring Walk and Arboretum to the east. The garden consists of cascading peat brick wall terraces that step down through the woodland, leading to the Victorian Sunken Garden, Stumpery, Bamboo Garden and Water Meadow. Within the garden a stone obelisk on top of a terraced mound draws your eye as you walk down from the Fountain Garden. As you reach the obelisk and look back up the hill there is a good view of the fountain in the distance, which is framed by a stone pillared gateway. The terraces are planted out with woodland shrubs such as Rhododendron spp., Daphne spp., flowering dogwood (Cornus florida/kousa spp.,), and Japanese maple (Acer palmatum) cultivars. Herb layer plants include the rampant wild garlic (Allium ursinum), Helleborus spp., lungwort (Pulmonaria spp), barrenwort (Epimedium spp.) and many different ferns. The area has a predominantly ericaceous theme and plants have been selected in order to provide good colour mostly in spring.
Overlooked by the peat wall terraces and next to a round pond, the small, shaded Victorian sunken garden contains a range of herbaceous plants and ferns set within small peat walls. These include snowbell (Soldanella villosa), delicate Asplenium Trichomanes and Athyrium filix-femina ‘Congestum Cristatum’. During spring and early summer, candelabra primulas flowers are complemented by the bold heart shaped foliage of Hosta ‘Wide Brim’, followed by daylily Hemerocallis ‘Gentle Shepherd’ and Astilbe ssp., from midsummer.