Shenandoah switchgrass is a culitvar of panicum virgatum, a species of ornamental perennial grasses. Shenandoah switchgrass is identifiable by the deep red color the otherwise green blades turn in summer, then deepening to a rich burgundy in fall. It's hardy and thrives in USDA Zones 5 through 9 and provides fall and winter interest in the garden. Switchgrass grows in a clumping upright fountain habit and reaches up to 6 feet in height at maturity. It requires little pruning, save the removal of dead or damaged foliage.
Inspect your switchgrass plants periodically during watering time to look for troubled areas. Remove any broken, dying or otherwise damaged blades or stalks throughout the growing season as you spy them. Place the cut at the base of the blade or stalk just above the crown of the clump and pull the cutting clean from the canopy.
Shear down the dead top foliage in winter after the first hard frost or leave the drying grass in pace to provide visual interest in the garden during winter. Cut back all of the dead grass in the early spring down to the crown to make way for fresh green growth. Discard or compost the cuttings.
Prune lightly to tidy the switchgrass that successfully overwinters in warmer climates. Remove only the damaged or unattractive individual blades by cutting them off at the crown and pulling them out. Cut back any blades that are lying on the ground from weather damage or have been trampled, in order to preserve the natural fountain form.