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Calamagrostis x acutiflora Karl Foerster:
A choice tall ornamental grass

The stately, upright grass Calamagrostis x acutiflora 'Karl Foerster', commonly called feather reed grass, is one of my all-time favorites.

It makes a striking five-foot tall exclamation point in the garden.

This is such a good plant that in 2001 it became the first ornamental grass to be named "Perennial Plant of the Year."

Karl Foerster's feather reed grass: origins

K.F. grass, as I like to call it for simplicity's sake, is named for German nurseryman, Karl Foerster, one of the big names in the renaissance of ornamental grasses in the garden.

Foerster introduced this grass, thought to be a natural hybrid of Calamagrostis epigejos and Calamagrostis arundinacea, to the nursery trade in 1950. Originally, he found it growing in the Hamburg Botanical Garden.

The name Calamagrostis x acutiflora (pronounced cal-ah-mah-gros'tiss ah-cute-i-floor' ah) is from the Greek for reed, kalamos, and agrostis, grass.

Calamagrostis x acutiflora 'Karl Forester' is a cool season grower with dark green, shiny foliage that appears in early spring and lasts until late fall.

Flowers appear in June - earlier than many other ornamental grasses. At first, they are loose, feathery and pinkish in color, then, through the summer, they become very narrow, gradually turning a wheaten color that lasts through the fall. The flower stems grow bolt upright and stand up well through summer and winter.

How to grow Calamagrostis x acutiflora 'Karl Foerster'

K.F. grass is hardy from Zone 4 to 9. It grows best in moist, well-drained fertile soil, and does well in moist heavy clay soil. In my garden, it thrives in both heavy clay soil and sandy soil.

This is a cool-season grass, which allows for planting or transplanting in spring or fall. You can easily propagate this grass by division, but the flowers are sterile so it can't be grown from seed. Fortunately, this means it is not invasive and will not seed itself around.

Like most ornamental grasses, Karl Foerster feather reed grass is easy to grow. It prefers full sun, but will take light shade, but too much shade causes it to flop a bit.

Annual maintenance consists of cutting the old growth down in early spring before new growth starts. We usually make the cut somewhere between 10 to 12 inches from the ground, as shown here.

K.F. grass grows out from the center, and after a few years, you may discover a hole-in-the-donut effect. When this happens, dig it up and divide it in spring.

Replant vigorous divisions from the outer sections. Or leave a section in the ground and dig up and divide the rest of the plant.)

I divided a couple of large mature clumps one spring and managed to get more than a dozen new plants from it, which allowed me to plant a dramatic swath on the hill at the front of our house very inexpensively (see picture below).

Designing with Calamagrostis x acutiflora 'Karl Foerster'

Besides its upright habit – which makes it a very architectural plant - one of the attractive features of this grass is that it moves gracefully with the breeze.

In a small garden, one or two clumps serve as good specimens or accents, especially when surrounded with lower-growing companions.

Its narrow growth habit makes it a good tall grass for tight spaces.

In larger spaces, Karl Foerster grass is a natural for mass planting. It's also a fast-growing screen plant to use alongside swimming pool fences or even as in informal hedge.

Good companions early in the season are daffodils and tulips. Later on, it mixes well with late-flowering perennials as coreopsis, coneflowers, liatris, Joe-Pye weed and rudbeckia.

Related information:

Growing and caring for Calamagrostis x acutiflora Karl Foerster
and other ornamental grasses

Ornamental grasses for shade

About Panicum or switchgrass

Back to introductory page on Ornamental Grasses

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