Muhly grass (Muhlenbergia capillaris) is a warm-season ornamental grass known for its fine-textured, deep-green foliage and stunning clouds of airy pink or purple plumes in the fall. This North American native forms a neat, fountain-shaped clump, offering color and movement through late summer and autumn. It is popular due to its dramatic seasonal display, low-maintenance nature, and exceptional tolerance for heat and dry conditions once established. Proper spacing is the first step in cultivating this grass, as it directly impacts the visual effect and long-term health of the planting.
Determining Spacing for Mass vs. Clump Planting
The distance chosen for planting Muhly grass depends on the desired aesthetic: a continuous, cloud-like drift or distinct, individual mounds. Mature clumps typically grow two to three feet tall and two to four feet wide. This mature size dictates effective spacing recommendations.
For a unified, sweeping display—known as mass planting—closer spacing is required. Planting the centers of the grasses 18 to 24 inches apart ensures the foliage and plumes grow together. This dense pattern creates a seamless blanket of color, maximizing the visual impact of the plumes.
If the goal is to highlight the natural, elegant form of each individual plant, wider spacing is appropriate. Position the grasses three to four feet apart on center to showcase their distinct, fountain-like shape. This distance allows for full air circulation and prevents the clumps from merging as they reach their maximum spread.
Preparing the Planting Site
Muhly grass requires full sun exposure, meaning the location should receive a minimum of six hours of direct sunlight daily. Insufficient sun causes weak foliage, leading to fewer and less vibrant fall plumes.
While Muhly grass adapts well to poor soils, excellent drainage is required. The plant will not tolerate consistently wet or soggy soil. If the existing soil is heavy clay, drainage must be improved by loosening the soil and incorporating gritty material or coarse organic matter.
The ideal planting time is in the spring after the last frost or in the early fall, at least a month before the first hard freeze. Dig the planting hole two to three times wider than the root ball, but no deeper. This allows roots to expand laterally without burying the plant’s crown too deeply.
Initial Care After Planting
The first growing season requires consistent moisture for the development of a strong root system. Immediately after planting, water the area thoroughly until the soil is saturated to the depth of the root ball. This helps settle the soil and eliminate air pockets.
For the first two to three months, water the plants weekly, aiming for a deep, infrequent soaking rather than shallow sprinkles. Allow the soil to dry slightly between waterings; check by inserting a finger two inches into the soil. Once the plant is established, indicated by vigorous new growth, its natural drought tolerance takes over.
Gently tamp the soil around the base of the plant after watering. Apply a light, two-inch layer of organic mulch to retain soil moisture and regulate temperature. Keep the mulch a few inches away from the plant’s crown to prevent rot and allow for air circulation.