Muhly grass (Muhlenbergia capillaris) is a warm-season perennial ornamental grass that forms dense clumps of slender, dark green foliage throughout the summer. Its signature feature is the cloud-like display of airy, pink or purplish-red plumes that emerge in the fall, offering a striking visual contrast to the autumn landscape. Known for its adaptability and low maintenance needs once established, Muhly grass is a popular choice for gardeners seeking drought-tolerant plants.
Site Selection and Planting
Muhly grass requires a location that receives full sun, defined as six or more hours of direct sunlight daily, to achieve the best bloom density and color. While it can tolerate some partial shade, insufficient light often results in fewer or weaker plumes in the fall.
The soil must be well-draining, as the grass cannot tolerate consistently wet conditions, which can quickly lead to root rot. Muhly grass thrives in poor, sandy, or rocky soils and is highly adaptable to various soil types, including clay, provided drainage is adequate. Lean soil is preferred, as overly rich soil can cause the foliage to grow too vigorously and become floppy.
Planting is best done in the spring or early fall, ensuring the plant has enough time to establish its root system before extreme weather hits. Dig a planting hole that is approximately twice as wide as the nursery container but no deeper, ensuring the top of the root ball is level with or slightly above the surrounding soil. After positioning the plant, backfill the hole and water thoroughly to settle the soil and eliminate any air pockets around the roots.
Routine Watering and Feeding
The watering needs of Muhly grass change significantly between establishment and maturity. For the first two to three months after planting, the grass requires regular moisture to develop a strong root system. During this initial phase, water weekly, allowing the top layer of soil to dry out between waterings, but never allowing the roots to become soggy.
Once established, the grass becomes highly drought-tolerant, making supplemental irrigation unnecessary in areas with regular rainfall. Deep, infrequent watering is recommended only during periods of severe or prolonged drought when the soil is dry to a depth of two inches or more. Overwatering is the most common mistake and should be avoided, as Muhly grass prefers to remain on the drier side.
Muhly grass is adapted to low-fertility conditions and does not require supplemental feeding. Applying too much fertilizer, especially those high in nitrogen, can encourage excessive foliage growth at the expense of its fall blooms. If the soil is exceptionally poor and the plant shows signs of pale or stunted growth, a light application of a balanced, slow-release fertilizer may be applied in the early spring.
Yearly Cutback
The annual cutback is the primary maintenance task for established Muhly grass. This process should be performed in late winter or very early spring, just before the first signs of new green growth emerge from the crown. Pruning too early, such as in the fall, can redirect the plant’s stored energy and weaken the plant before the winter dormant period.
The technique involves cutting the entire clump of old foliage down close to the ground, typically leaving four to six inches of growth above the soil line. Using sharp shears or a hedge trimmer provides a clean cut and makes the task efficient, especially for mass plantings. The resulting clippings can be collected and discarded, or shredded and used as a thin layer of mulch around the plant, taking care not to bury the central crown.