The ornamental grass Blue Fescue (Festuca glauca) is a popular, low-maintenance, cool-season plant known for its distinctive, spiky blue-gray foliage. This clumping perennial maintains its color through mild winters. Annual trimming is beneficial for the plant, though the method differs significantly from mowing a lawn. Regular maintenance encourages the plant’s characteristic dense, mounding form and vibrant color.
The Rationale for Cutting Back
The primary reason for cutting back Blue Fescue is to remove the buildup of old, dead foliage, commonly referred to as thatch, which accumulates within the center of the clump. This spent material reduces air circulation and can trap moisture, creating an environment susceptible to fungal diseases and crown rot. Removing this dead matter significantly improves the plant’s health and longevity.
Shearing forces the plant to redirect energy into producing fresh, new foliage from the crown. This stimulated growth is typically a more vibrant, intense shade of blue-gray. If the old, faded blades are not removed, they will flop over and obscure the new growth, causing the plant to lose its attractive, tidy, mounding shape. A clean cut ensures the plant starts the growing season with a uniform, fresh appearance.
Optimal Timing for Shearing
The most beneficial time to perform this maintenance cut is in late winter or early spring, just before the plant begins its active growth cycle. This timing ensures the winter-damaged foliage is removed right before the new, bright blue blades emerge. Waiting until after new growth has started makes the task difficult, as you risk accidentally cutting the fresh foliage.
Trimming in late fall or early winter is discouraged because the remaining blades provide insulation for the crown during freezing temperatures. Leaving the foliage intact during winter also provides visual interest in the landscape. Waiting until the threat of severe cold has passed maximizes protective benefits and ensures the plant is ready for a strong burst of spring growth.
The Proper Pruning Technique
The process of pruning Blue Fescue involves cutting the entire clump back uniformly, rather than simply removing individual dead blades. Use sharp, clean tools, such as hand shears, hedge clippers, or even electric trimmers, to make the job easier and ensure a clean cut that minimizes damage to the grass blades. The goal is to reduce the plant’s height by about two-thirds, leaving approximately 2 to 4 inches of growth above the ground.
The process can be simplified by gathering the entire clump of foliage into a tight bundle, like a ponytail, before making a single, clean cut across the top. Once cut, remove all the trimmings and any remaining dead debris from the center of the crown. This thorough cleaning allows sunlight and air to penetrate the base of the plant, encouraging healthy, dense regrowth.
When Division is Necessary
While annual shearing maintains the foliage, Blue Fescue is a relatively short-lived perennial that requires a different type of maintenance to ensure its survival: division. After approximately three to five years, the plant’s center often becomes woody and dies out, which results in a characteristic “donut” shape where only the outer ring of foliage remains healthy. Simple pruning will not fix this structural issue.
Division involves digging up the entire root ball, a task best performed in the spring alongside the annual shearing. The dead center of the clump should be discarded. The healthy outer sections can then be separated using a sharp spade or knife and replanted, effectively rejuvenating the parent plant and providing new clumps.