Calamagrostis x Acutiflora
Calamagrostis x acutiflora, commonly called feather reed grass, is a member of the Poaceae family, which also contains most of the common turf grasses such as fescue and bluegrass. Calamagrostis, however, is a dramatic ornamental grass useful in mass plantings or as a strong vertical accent in a perennial bed.
By far the most common and popular cultivar is 'Karl Foerster,’ named plant of the year in 2001 by the Perennial Plant Association, which proclaimed it "one of the most versatile, attractive, and low maintenance ornamental grasses."
Arching, shiny green foliage begins growth in early spring followed in summer by a central clump of flower stems rising to 5 ft. and topped with open feathery flower heads in striking pink or pale plum. As the seed heads mature, they become quite narrow and turn to a golden tan. Foliage is generally 3-4 ft. high by2-3 ft. wide in a slowly expanding tussock.
The ultimate size of ‘Karl Foerster’ is dependent on the amount of water received and how long it grows before divisions are taken. Size also depends on soil fertility. If larger plants are desired, amend the soil with compost before planting and irrigate moderately about twice a week. In hotter situations with less than optimum moisture, summer heat may cause feather reed grass to enter summer dormancy. Although ‘Karl Foerster’ tolerates a wide range of growing sites, including clay, it does best in full sun to part shade and in moist but well-drained fertile soil.
This grass is problem-free in Sonoma County’s climate and requires little maintenance. It is a deciduous grass that looks best when cut back to about 4 in. above the g round in late winter or very early spring before winds scatter the dried foliage.
‘Karl Foerster’ can be propagated easily by division, usually in spring or fall. Its seeds are sterile; thereby, this grass will not self-seed and become an invasive problem. It also means that it cannot be propagated from seed.
Calamagrostis sways gracefully in the faintest breeze. A row at the edge of a pool, along a fence or roadway will move gloriously in the wind. Single specimens stand out against lower perennials like long-blooming Achillea or Nepeta and late-summer and fall-blooming perennials such as Caryopteris(bluebeard), Gaura, Rudbeckia (gloriosa daisy, black-eyed Susan), or Perovskia(Russian sage).
Two variegated Calamagrostis cultivars are 'Avalanche' and 'Overdam'. Both are variegated with white margins, are more compact than ‘Karl Foerster,’ and develop a more delicate texture. ‘Overdam’ shows more green than white in its leaf stripe and flower stems on both are slightly shorter.