Pruning hairy sedge encourages more robust growth and helps maintain its desired form. Regular trimming can revitalize the plant, ensuring it invests energy in thriving, rather than sustaining old or overgrown foliage.

The optimal times for pruning or trimming hairy sedge are early spring and winter. These seasons align with hairy sedge's dormancy period when the plant's growth is least active. Pruning during early spring, just before the new growth starts, helps hairy sedge to direct its energy towards producing new, healthy shoots. It also allows for the removal of any dead or damaged foliage that may have occurred over winter without stressing the plant, as it has yet to put forth significant growth. Winter pruning is suitable as well, especially in late winter, because the plant is dormant, and removing parts of it won't interfere with its developmental processes or flowering cycle. Pruning during these times minimizes the risk of inviting disease or pests that often occur if pruning when the plant is actively growing or during wet periods. Also, since hairy sedge is not in its active growth or reproductive stage, pruning won't affect its ability to produce flowers or seeds.