Coed Mawr farm is an important conservation area in Radnorshire with major protected natural habitats. Several hectares of rare grassland have been declared SSSI (Sites of Special Scientific Interest) as well as the River Edw on the Coed Mawr side SAC (Special Area of Conservation). The fields are ideally suited to cattle grazing and therefore well adapted to fatten cattle on the historic Drovers’ trails. The Ancient Semi Natural Woodland, with bluebells, is part of the last 2% of remaining native wild woodland in the UK. Coed Mawr is Welsh for The Big Wood.

About 5 hectares of woodland survived the national denudation due to the steep terrain. This area has been successfully extended in the last 20 years with Sessile Oaks germinated from acorns gathered on the farm. Over 1000 trees were planted in the two new areas, which unite the lower with the upper woodland fragment to form a continuous habitat. The woodland management includes annual pruning of the new woodland trees and a regime of coppicing to enhance the flora and related wildlife. Elsewhere on the farm the original hedgerows have been restored and three new ponds created, to enhance wildlife habitats. The farm has been organic since 2000.

The historic homestead estimated to pre-date the 15th Century was extended in 1650 and restored by Craig Hamilton to its 17th Century character. The surrounding gardens and cultivated areas have been designed to integrate with the original heritage landscape.

Work on the creation of the gardens began in 1995 soon after the acquisition of the farm by Craig Hamilton and Diana Hulton. Initial plans were made for an Orchard and KItchen Garden, which Diana changed into a Rose Garden in 2003. The Rose Garden is characterized by Craig’s loggia with stone columns reminiscent of mediaeval cloisters. There are newly planted zones with ornamental old rose varieties but the main beds are hybrid teas for picking. Thus the Rose Garden is a utility garden, which offers a delightful retreat and contemplative views of the surrounding landscape. The Espalier part of the Rose Garden contains apple and plum trees on Julien stock, which have struggled to mature at the existing altitude and under severe winter conditions. In spring, the Espalier area is a bulb garden (mainly crocus and daffodil) followed by blossom and in summer it is a natural wild flower area. On the steep banks Blackcurrant, Redcurrant, Blueberries and Raspberries flourish above two productive vegetable beds. In 2008, the Rose Garden loggia was extended with twin glass houses in the style of the Schloss Glienicke Greenhouse, Berlin-Brandenburg.

In the main orchard, young 15-20 year-old, late-blossom traditional culinary apple and dessert apple trees produce enough fruit for 2000 bottles of apple juice per season. The orchard is an important addition to the wildlife habitats at Coed Mawr. Other fruit trees include pear and plum. Culinary apples include Blenheim Orange, Bountiful, Catshead, Forester, Galloway Pippin, Monarch, Stirling Castle, Ten Commandments, Wheeler’s Russet.

A small informal patch of land, with a pit lavatory, was the original kitchen garden near the old house and now part of the foundations of Craig’s New Classical Wing. This development includes a formal Walled Garden leading to a long south-facing loggia. To the rear, the new wing forms the southern end of a long narrow Inner Courtyard between the Old House and the Barn conversion enlivened by an avenue of potted Box and Yew.

To the south and east of the Classical Wing the landscape has become a Memorial Garden with several monuments designed by Craig Hamilton. The elevated monument to Selene is on the east west axis of the entrance to the Rose Garden and faces the volcanic hills and setting sun. The recently built Memorial Pond and Pergola structures face west in a stepped landscape that rises to a small temple. Grassy wildflower banks and lawns give way to the bluebell wood.

The Memorial Garden or "Elysian Fields" at Coed Mawr is inspired by the 18th Century Sculptor Johannes Wiederwelt's Memorial Garden at Jaegerspris in North Zealand, Denmark. The monuments thus far include memorials to the architects Schinkel, Persius, Von Klenze, Plecnik, Harvey Lonsdale Elmes and Hack Kampmann as well as a monument to Craig Hamilton's architectural mentor Professor Barrie Biermann.