Feather Reed Grass 'Karl Foerster' Calamagrostis x acutiflora 'Karl Foerster'

'Karl Foerster' is a popular and attractive cultivar of Calamagrostis x acutiflora. It is a cool-season, ornamental, feather reed grass that was awarded the Perennial Plant of the Year Award in 2001. This plant is named in honor of German nurseryman Karl Foerster, who discovered this plant and introduced it commercially in 1950. It is a member of the grass family (Poaceae.)

This cultivar prefers full sun to partial sun and grows in a wide range of soil conditions, including clay. Cool-season grasses grow most in the spring when the temperatures are below 75 degrees Fahrenheit. During the summer, they tend not to grow very much, but maintain their color. Cool-season grasses are best cut back in early spring, leaving about 1/3 of the plant. Harshly cutting back this grass can be detrimental. It spreads slowly by rhizomes and is best propagated by division in the spring or early fall. This plant is highly resistant to deer and rabbit grazing, and it is tolerant of wet soils, drought, and clay soils. It requires very little maintenance. During hot, humid, or wet summers, this plant suffers and is susceptible to rust diseases.

'Karl Foerster' plant can grow up to 3 to 5 feet tall and 1 to 1.5 feet wide, with bright green, glossy, narrow, arching, upright leaves. Initially, the head of the flower emerges green, then airy with pinkish-purple plumes that appear on an upright stalk in early to mid-summer. After a couple of weeks, the inflorescence changes to dark maroon, then becomes bronze, and eventually tan. The plumes will become narrower and golden tan; this color lasts through the fall. The stalk rises above foliage and measures up to 5 feet tall. The flower stalk remains through the winter. The flowers on this cultivar appear about two to three weeks before the species plant, C. x acutiflora.

The cultivar, 'Karl Foerster', is nearly identical to another cultivar, Calamagrostis x acutiflora 'Stricta.' They are often confused and mislabeled in many nurseries.  A helpful hint: 'Karl Foerster' is sterile and does not self-seed. 'Stricta' is about 1 to 2 feet taller at maturity and flowers about 2 weeks later. 

Consider planting along ponds or streams in mass plantings, groups, or as a specimen. Does well in narrow, vertical spaces.

Insects, Diseases, and Other Plant Problems: No significant insect pests or diseases. May be susceptible to rust in the presence of extended periods of rain. This grass tends to fall over if grown in shade.

More information on Calamagrostis x acutiflora.