Calamagrostis arundinacea [ka-la-mo-GROSS-tis, a-run-din-uh-KEE-uh] is a species of bunch grass and part of the Poaceae family.
It’s native to parts of Asia, including India, China, and the Korean peninsula.
Calamagrostis arundinacea is commonly called reed grass and a few other names:
The names refer to the feathery flowers and seed plumes appearing during the fall season.
The ornamental grass grows in wet soils and poor conditions, making it easy to cultivate outside of its native region.
Korean Feather Reed Grass Care
Size and Growth
Korean feather reed grass grows in clumps with a mound of narrow green leaves.
The leaves typically reach up to 2′ feet tall and measure about a half-inch wide.
Each mound offers about 2′ to 3′ feet of coverage when fully mature.
Flowering and Fragrance
Toward the end of summer, tall flower spikes appear from the center of the mounds.
The stems reach close to 4′ feet tall and produce pink-tinged flower plumes.
The plumes slowly mature throughout October and November, eventually turning a light tan color as the seeds ripen.
By early winter, the flowers wilt and the seeds spread.
Light and Temperature
Korean feather reed grass tolerates cold temperatures, including freezing conditions during the winter.
It is suited for year-round growth in USDA hardiness zones 4 to 9, covering most of North America.
The plant should receive light shade and protection against bright afternoon sunlight.
If grown in a container and placed indoors, it should receive morning sunlight and filtered light throughout the rest of the day.
Watering and Feeding
Korean feather reed grass needs consistent moisture.
The soil should never dry out, especially during its first few years.
After the plant is established, it becomes partially drought-tolerant.
Most plants will need watering about twice per week during the warmer months.
Depending on the region, outdoor plants may not need additional water throughout the winter.
Only fertilize during the warmer months if the plant appears to develop yellow leaves, which may indicate a lack of nutrients.
Use liquid fertilizer mixed with water once per month as needed.
Soil and Transplanting
Plant in average soil. Unlike many other ornamental kinds of grass, reed grass thrives in soil with heavy clay and wet soil.
Almost any soil should work, but adding compost or peat moss to the soil helps ensure optimal growth and larger plants.
Potted plants may eventually outgrow their homes.
Divide and transplant mature plants every few years to keep the plant from becoming root-bound.
At the end of winter, cut the clumps of grass to the ground.
New shoots should appear at the start of spring and quickly reach 2′ feet tall.
How To Propagate Calamagrostis Arundinacea
Propagate with seeds or division.
The seeds appear after the flowers start to wilt.
- Collect the seed pods after they ripen and turn a dark brown color.
- Allow the pods to dry thoroughly before opening.
- Separate the debris and seeds, storing the seeds in an envelope or paper bag.
- Start the seeds in small pots several weeks before the last threat of frost.
- Use regular potting soil and keep it moist.
- After the seedlings appear, wait for several leaves to develop before transplanting outdoors or to larger pots.
The easier propagation method is division.
- Separate a mature clump in the fall or spring.
- The clump should have at least six growing points near the base.
- If the mound has fewer growing points, it may not bloom during the first year.
- Carefully dig up the soil around the mature plant.
- Lift it from the soil and shake off some of the loose dirt.
- Separate the mound into two or more sections, ensuring each section has multiple clumps of grass.
- Place the divided sections in pots or directly in the ground, providing 2′ to 3′ feet of spacing between each plant.
- The soil should remain moist throughout the rest of the season, ensuring the young plants receive plenty of hydration.
Calamagrostis Arundinacea Pest or Disease Problems
The main issues to worry about include typical pests such as aphids or spider mites.
These pests are rare but more common with potted indoor plants.
Treat infestations with sprays of water or neem insecticide.
Maintaining higher humidity levels during the summer may also reduce the risk of spider mites.
The plant doesn’t suffer from any serious pest or disease problems.
However, Korean feather reed grass is an aggressive plant and has the potential to become invasive in some regions.
While it’s not listed as an invasive species, it may overtake nearby plants in the garden.
Suggested Korean Feather Reed Grass Uses
Use Korean feather reed grass to accent gardens or landscapes.
Group the plants to create denser coverage.
The plant also helps cover moist areas such as low spots in the ground near ponds or streams.