Calamagrostis

fluffy flower plumes

Feather reed grasses

Full sun to partial shade; average, well-drained soil

Feather reed grasses (Calamagrostis) are a great choice when you need a tall grass for a summer combination. ‘Karl Foerster’ feather reed grass (C. × acutiflora) typically tops out at 4 to 6 feet tall when its plumy flowers reach their full height in early to midsummer. It’s suited for Zones 3 to 9. Korean feather reed grass (C. brachytricha) is a bit shorter—usually 3 to 4 feet in leaf and 4 to 5 feet when it flowers in late summer to early fall—and a bit less hardy: usually Zones 4 to 9.

Both of these feather reed grasses are clump formers, so while the individual plants will expand a bit each year, you don’t have to worry about them taking over a border with creeping roots. ‘Karl Foerster’ is also seed sterile, so it won’t produce seedlings, either (something Korean feather reed grass can do, though usually not to the point of being a serious problem).

Color Considerations

In leaf, feather reed grasses are mostly a rich, glossy green that works well with a wide range of flower and foliage colors. There are a few variegated cultivars of C. × acutiflora, including white-striped ‘Avalanche’ and ‘Overdam’ and yellow-striped ‘Eldorado’, all of which are usually a foot or so shorter than ‘Karl Foerster’. Emphasize their markings with white- or yellow-flowering partners, such as daffodils or tulips in spring or Shasta daisy (Leucanthemum × superbum) or coreopsis (Coreopsis) in summer.

The flower plumes of feather reed grasses tend to have a light purplish pink blush, which you could emphasize with pink-flowering partners appropriate to their bloom time. Match ‘Karl Foerster’ with purple coneflower (Echinacea purpurea) or red valerian (Centranthus ruber) in early to midsummer, for instance, or pair Korean feather reed grass with obedient plant (Physostegia virginiana) in late summer. The plumes of feather reed grasses are also pale enough to hold up well with white-flowered partners, such as giant fleeceflower (Persicaria polymorpha) for ‘Karl Foerster’ and false aster (Boltonia asteroides) for the Korean species, or with white-variegated leafy companions for either.

As the aging plumes turn tan, echo their color with peachy to tan heucheras (Heuchera), such as ‘Caramel’; bronzy New Zealand sedges (Carex), such as ‘Toffee Twist’ weeping brown sedge (C. flagellifera); or the seed heads of other grasses, like those of fountain grasses (Pennisetum) or tufted hair grass (Deschampsia cespitosa).

A Perfect Match

‘Karl Foerster’ feather reed grass is so distinctly upright that it makes a great divider or screen in a narrow bed or border: between a walkway and a wall, for instance, or around a deck or patio. I often pair it with tall-stemmed pink flowers, such as ‘Black Beauty’ Orienpet lily (Lilium) or sweet Joe-Pye weed (Eupatorium dubium), but I’ve also admired it planted with purple-blues, like those of lavenders (Lavandula) or Russian sages (Perovskia).

Shapes and Textures

Feather reed grasses have a distinctly upright form. Use single clumps as accents among lower perennials: They make a particularly striking contrast to mounded bedmates, such as aromatic aster (Aster oblongifoliums), blue mist shrub (Caryopteris × clandonensis), and bluestars (Amsonia). Or match them with other tall growers, such as ironweeds (Vernonia) or ‘Lemon Queen’ perennial sunflower (Helianthus).

With their long, narrow leaves, slender stems, and fluffy flower plumes, these fine-textured grasses add variety when paired with strong bloom shapes: Combine them with large, daisy-form flowers, like those of echinaceas (Echinacea) or rudbeckias (Rudbeckia), for instance, or with the bold blooms of daylilies (Hemerocallis) or hardy hibiscus (Hibiscus). Or emphasize their vertical inflorescences with other plumy perennials, such as Russian sages (Perovskia), or with partners that have slender, spiky bloom clusters, such as mountain fleeceflower (P. amplexicaulis).

Seasonal Features

Feather reed grasses are quick to send up their foliage as soon as the soil starts to warm up in spring. The flower plumes of ‘Karl Foerster’ and other selections of C. × acutiflora usually open in June, while August or early September is more typical for Korean feather reed grass. The aging plumes turn tan, dry in place, and linger into winter, along with the skeletons and seed heads of asters, purple coneflower (Echinacea purpurea), upright sedums (Sedum), and other winter-persistent perennials.

Bloom Buddies

Marvelous Matches for Flowering Combos

While full sun and average to moist but well-drained soil suit both types of feather reed grasses (Calamagrostis), these beauties can also grow in partial shade—particularly Korean feather reed grass—and somewhat dry soil. Below are some of the compatible companions that bloom around their peak flowering periods.

Combine with feather reed grass (C. × acutiflora):

Anise hyssops (Agastache)

Bee balms (Monarda)

Blazing stars (Liatris)

Carolina phlox (Phlox carolina)

Echinaceas (Echinacea)

Fleeceflowers (Persicaria)

Globe thistles (Echinops)

Knautias (Knautia)

Meadow phlox (Phlox maculata)

Perennial salvias (Salvia)

Pincushion flowers (Scabiosa)

Queen-of-the-prairie (Filipendula rubra)

Rattlesnake master (Eryngium yuccifolium)

Rudbeckias (Rudbeckia)

Shasta daisy (Leucanthemum × superbum)

Summer phlox (Phlox paniculata)

Tuberous-rooted Jerusalem sage (Phlomis tuberosa)

Yarrows (Achillea)

Combine with Korean feather reed grass (C. brachytricha):

Asters (Aster)

Caryopteris (Caryopteris)

False aster (Boltonia asteroides)

Goldenrods (Solidago)

Ironweeds (Vernonia)

Japanese anemones (Anemone)

Japanese burnet (Sanguisorba tenuifolia)

Joe-Pye weeds (Eupatorium)

Monkshoods (Aconitum)

Montauk daisy (Nipponanthemum nipponicum)

Mountain fleeceflower (Persicaria amplexicaulis)

Perennial sunflowers (Helianthus)

Russian sages (Perovskia)

Turtleheads (Chelone)