How to Plant Karl Foerster Ornamental Grass

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Close-up of "Karl Foerster" ornamental reed grass
Image Credit: Mark Herreid/iStock/Getty Images

Named for the European plantsman that discovered it decades ago, "Karl Foerster" feather reed grass (Calamagrostis x acutiflora "Karl Foerster") remains one of the leading ornamental grasses. This award-winning perennial grass needs little care and it has early summer blooms and tight, vertical growth. Hardy in U.S. Department of Agriculture plant hardiness zones 4 through 9, versatile "Karl Foerster" simplifies planting and beautifies gardens all year.


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Feathery Flexibility

"Karl Foerster" feather reed grass prefers a moist, fertile, sunny spot but adapts readily to other conditions. Unlike many ornamental grasses, it tolerates heavier clay soil, light shade and seasonal dryness in its planting bed. Free from serious disease and insect pests, this cool-season grass stays healthiest where air circulates freely. Its seeds are sterile, so self-seeding into nearby areas is never an issue. Its heaviest growth periods come in spring and again in fall as temperatures drop. When choosing your planting site, give "Karl Foerster" its preferred conditions whenever possible, but let its versatility and flexibility shine when needed.


Features to Consider

Choose a planting site that allows full enjoyment of "Karl Foerster" and its year-round ornamental features. This refined, non-spreading, clump grass grows leaf blades 3 to 4 feet tall, then tops them with 5- to 6-foot, creamy white, midsummer plumes blushed with pink. The flowers tighten, age to golden tan and stay on throughout winter. The plant provides a slender, vertical accent at just 18 to 24 inches wide. Though stiff, the flower stems catch the lightest breeze. "Karl Foerster" fits in plans from stunning mass groupings to containers flanking formal entryways. In fall, fresh green basal growth complements tan blades and seed heads. Plant it where you can easily sneak cut stems for indoor arrangements.


Planting Feather Reed

Spring planting gives "Karl Foerster" all season to settle in. Plant bare root grasses in spring only. For container-grown "Karl Foerster," fall works, too -- just plant one full month before your ground freezes. Prepare mass planting beds in fall. Cover the area with 3 inches of organic compost, till it in, and let winter work the soil. In spring, incorporate 1 pound of granular, slow-release, 10-10-10 fertilizer per 100 square feet. Wear gloves, protective clothing and safety eyewear. Dig holes two times the container width and no deeper than the grass sat in its pot. If bare root, let the soil mark guide you. Space grasses 4 to 5 feet apart, except for hedges or screens. Then use 2- to 3-foot spacing in lines or staggered rows.


Maximizing Foerster's Beauty

Water "Karl Foerster" grass well after planting, and keep soil uniformly damp through the first season. Let the grass spend winter standing tall. The stems and leaf blades add interest and insulate the crown against cold. Cut the grass back in early spring. "Karl Foerster" starts early, so make this one of your first chores. For easy cleanup, wrap twine tightly around the grass, then cut the base back to the ground. Use sharp bypass pruners for singles or hedge trimmers for masses. Wear protective gear and eyewear, and sterilize the blades by spraying them with household disinfectant before and after you cut. Mulch "Karl Foerster" grasses annually. Established plants normally don't need fertilizer or watering.


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