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 other grasses that have a weeping or floppy habit, feather reed grasses look tidy all year, even after they bloom.
Feather reed grasses are semi-evergreen, meaning they will retain their color in milder climates and weather. They also tend to grow in well-behaved clumps, which means you do not have to worry about them aggressively spreading throughout your garden or becoming invasive. These features make them an ideal choice for most gardens.
- 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.
Most feather reed grasses are reliably perennial in USDA Hardiness Zones 5 through 9.
Plant feather reed grasses in full sun to partial shade. They will be smaller and flop a bit if grown in too much shade.
There is a bit of variation in the mature size of feather reed grasses, but you can generally expect them to grow about 4 to 6 ft. (h) x 2 to 3 ft. (w)
June through 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.
- Calamagrostis x acutiflora 'Karl Foerster': Green leaves, reddish flowers. 3 to 4 ft. tall.
- Calamagrostis x acutiflora 'overdam': White variegated leaves, white flowers. 2 to 3 ft. tall.
- Calamagrostis x acutiflora 'avalanche': Yellow variegated leaves, golden-brown flowers. 2 to 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 to 4 ft. tall.
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.
These grasses provide a nice architectural, vertical accent, especially in smaller gardens. Because of their upright nature, feather reed grasses will create 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.
- 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 slightly damp soil and can survive even poorly draining soil. Once established, feather reed grass is drought tolerant. Your feather reed grass will be a smaller plant if grown in a dry site.
Care and Maintenance
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 through 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 of feather reed grass 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. While they don't spread out of control, the clump does get larger. To prevent them from dying out in the center, they will eventually need to be divided, generally, every 3 to 5 years, to divide in the fall or early spring. Gardeners in cold climates will have better luck dividing in the early spring.
Pests & Problems
Along with their easy growing habit, feather reed grasses are virtually pest free.