Vegetation management is important to enhance the setting of the monument. By 2023, the Nevern Castle site was difficult for visitors to understand as the vegetation had grown tall, obscuring the features such as the motte and Square Tower, and their relationship to one another. A programme of scrub clearance in 2023 and 2024 (carried out by Pembrokeshire Coast National Park) has opened up vistas and enabled a clearer view of the motte, inner castle and ditches.
The areas of grassland around the Castle Motte and Bailey, and the ditches and surrounding areas, are under conservation management to increase the area’s biodiversity.
Many wildflowers cannot compete with coarse, tussocky grass, which can reduce the grassland to a single-species monoculture, with a consequent reduction in animal species.
To improve the biodiversity of the site, there is a cut midway through summer and another in late August. These focus on the main earthwork features on site including the motte, ramparts, rock cut ditch and square tower. The main interior section is left largely uncut during the summer, except for a few paths. The entire area is cut towards the end of the growing season. All arisings (cuttings) are removed. This decreases levels of nutrients in the soil allowing a more varied sward and encouraging a greater variety of plants such as wildflowers and finer grasses.
Managing some areas as mosaics of habitats, and allowing short grass, longer grass, mixed scrub and woodland edge to co-exist, increases the variety of flowers, insects and birds in a relatively small area and enhances the attractions of the landscape of Nevern Castle.
In addition to the vegetation management, there is also a felling programme for trees, including those suffering from ash dieback, that need to be cut at the site.