By Master Gardener Michael Harrelson, reprinted here with permission in Let’s Talk Plants! April 2022.
Pink Muhly Grass or Pink Hair Grass, Muhlenbergia capillaris, is an unsung hero in landscaping plants. Beautiful and easy to grow, this glossy, wiry, tall grass fits into landscapes both structured or wild.
Although not a native to Southern California, Pink Muhly grass is an ornamental, non-invasive, drought tolerant plant. Since it does not aggressively reseed, it is cited in numerous sources as a good replacement plant for invasive grasses. Pink Muhly is quite suitable for our climate and not very picky about its growing environment.
Growing 3-4 feet high and 2-3 feet wide, Pink Muhly prefers full sun but tolerates partial sun well too. Plants tolerate poor soils as long as drainage is good. Although it can grow in moist, marshy conditions it is quite happy with little watering. It can survive on strictly rain and dew moisture, but in the heavy heat of summer and early fall, watering helps keep the plant looking its best. In coastal areas, Muhly grass tolerates salty air and windy conditions and will remain evergreen where there is no frost. The dense grasses provide good cover for small wildlife and the seeds supply food for birds and small mammals.
Pink Muhly blooms from late summer to early winter before going semi-dormant for a few months. Once the plants have passed their peak bloom time, trim back the grasses in late winter or early spring. February is the ideal month for pruning. If you wait to cut plants back later in the year, you won’t kill the plants, but they will look chopped instead of wispy when they should be at their peak the following bloom season. The grasses can be trimmed to 2 inch high clumps or down to the ground.
Pink Muhly doesn’t throw seeds invasively, plants can be propagated by seed or by dividing plant clumps. Digging up and dividing bigger clumps every three to four years is recommended so that the plants don’t get too thick. Chop the clumps of grass in half or into thirds. Replant the biggest clump keeping roots moist during the first month. The remaining clumps can be planted elsewhere, given to a gardening friend, or simply composted. Some plants might lose their pink color over time so remove and replace if necessary.
Feed grasses in spring with a balanced slow-release fertilizer. Apply 1-2 inches of mulch outside the root zone at the base of the plant to retain consistent moisture and keep weeds to a minimum.
Muhly grass is pretty tough but not always pest-free. Overwatering, lack of drainage, and lack of air circulation can create an environment appealing to aphids, mealybugs, rot, slugs, and snails. Watering overhead can promote rust. Gophers and rabbits can chew the plants down.
Pink Muhly grass is attractive when planted en masse, great for defining borders or for filling areas with poor soil conditions. These delicate grasses are especially beautiful when pink blooms are backlit by early morning or late afternoon sun, backlighting the pink blooms like whimsical puffy clouds.