Feather Reed Grass (Calamagrostis x acutiflora)

Feather Reed Grass 'Overdam'
The Flowers, or Inflorescence, of Feather Reed Grass 'Overdam'. Photo: Georgianna Lane / Getty Images

Overview and Description:

The Feather reed grasses (Calamagrostis x acutiflora) are cool season, clump forming ornamental grasses that bloom early in the season and remain tall, straight, and upright, throughout the growing season, unlike many grasses that have a weeping or floppy habit.  Feather reed grasses are semi-evergreen, meaning they will retain their color in milder climates and weather. They also tend to be well-behaved clump formers, so you do not have to worry about them aggressively spreading throughout your garden or becoming invasive..

  • Leaves: Narrow and upright blades. There are varieties with variegation and in different shades of green and greenish-yellow.
  • Flowers: Slightly shaded yellow, white or red, changing to a buff color for the fall. The flowers, or inflorescence, are held above the leaves and persist throughout the winter.

Botanical Name:

Calamagrostis x acutiflora

Common Name:

Feather reed grass

Hardiness Zones:

Most feather reed grasses are reliably perennial in USDA Hardiness Zones 5 - 9.

Exposure

Plant feather reed grasses in Full sun to partial shade. They will be smaller and flop a bit if grown in too much shade.

Mature Size:

There is a bit of variation in the mature size of feather reed grasses, but you can generally expect them to grow about  4 - 6 ft. (h) x 2 - 3 ft. (w)

Bloom Period

June - July. Although ornamental grasses are not grown for their flowers, they can be quite attractive, especially when the light shines through them.

Feather reed grasses bloom early and retain their inflorescence all season. Most of the hybrids are sterile, so you don't have to worry about self-seeding.

Suggested Varieties:

  • Calamagrostis x acutiflora 'Karl Foerster' - Green leaves, reddish flowers. 3-4 ft. tall.

     

  • Calamagrostis x acutiflora 'Overdam' - White variegated leaves, white flowers. 2-3 ft. tall.

     

  • Calamagrostis x acutiflora 'Avalanche' - Yellow variegated leaves, golden-brown flowers. 2-3 ft.  tall.

     

  • Calamagrostis brachytricha (aka Stipa brachytricha Korean Feather Reed Grass - A related grass which makes a nice alternative in partial shade. A bit less upright, but well-behaved. 3-4 ft. tall.

Design Suggestions:

Feather reed grasses are very versatile, working well as specimen plants or in mass plantings. They are a nice complement to the late blooming colors of fall.

They provide a nice architectural, vertical accent, especially in smaller gardens.Because of their upright nature, feather reed grasses will created a lovely swaying screen.

Since feather reed grasses are fond of damp soil, they make an excellent choice for bog-like areas around water gardens or even around swimming pools. Their compact clump-forming growth also makes them a perfect fit in containers.

Growing Tips for Feather Reed Grasses:

Planting: Ornamental feather reed grasses are very easy growing. They are propagated by division, not seed, so you’ll need to start with an existing plant.

Plant at the same depth as it is in the pot.

Soil: Feather reed grass is tolerant of a wide range of soils and growing conditions, although a rich, well-draining soil with a neutral pH is ideal. It prefers a slightly damp soil and can survive even poorly drained soil. Once established, feather reed grass is drought tolerant. Your feather reed grass will be a smaller plant if grown in a dry site.

Caring for Feather Reed Grass:

Since Calamagrostis is an early blooming, cool season grass, it can be cut back in the fall. However it looks nice all winter and many gardeners prefer to leave it standing until early spring. Just don’t wait too long in spring, to cut it back, or the new grass will start to grow though the old blades, making it difficult to shear without cutting the new blades as well. Cut back to about 6 inches from the ground.

The cultivated varieties tend to be sterile and set no seeds that could cause them to spread aggressively. They are also clump forming, rather than spreading by rhizomes. They will eventually need to be divided, generally every 3-5 years, to prevent them from dying out in the center. Divide in the fall or early spring. Gardeners in cold climates will have better luck dividing in the early spring.

Pests & Problems:

Virtually pest free.