Calamagrostis x acutiflora [ka-la-mo-GROSS-tis, ak-yoo-tih-FLOR-uh] is a hybrid of two ornamental grasses of Calamagrostis species – Calamagrostis arundinacea and Calamagrostis epigejos – native to Europe and Asia.
The hybrid plant from the family Poaceae is one of the most widely grown ornamental grasses, all over the world, and is also naturally found in some areas of Europe.
This ornamental grass species also has numerous cultivars out of which Calamagrostis x acutiflora ‘Karl Foerster’ is most widely grown.
Some other popular varieties of the grass are:
- Calamagrostis x acutiflora ‘overdam’
- Calamagrostis x acutiflora ‘avalanche’
- Calamagrostis brachytricha
- Calamagrostis arundinacea
Calamagrostis x acutiflora is named after its genus and the shape of its flowers – Calamagrostis means reed and acutiflora means pointed flowers.
However, it is generally known with the common name feather reed grass due to its feathery flower spikes.
Feather Reed Grass Care
Size & Growth
Feather reed grass is a deciduous, perennial plant known for its attractive foliage.
It features clumps of long narrow bright green leaves, which grow up to 18” to 36” inches in height.
The leaves of calamagrostis x acutiflora Karl Foerster feather reed grass, the most popular cultivar of feather reed grass, grow up to 3’ feet tall.
By the way, Karl Foerster was awarded the Perennial Plant of the Year Award® in 2001.
The foliage is arching and shiny and makes a beautiful display on its own, but looks even more beautiful when it is supplemented with the flowering stalks in summers.
The best time to grow the vertical feather reed grass is from May to September.
Flowering and Fragrance
In the late summer, this handsome ornamental grass produces long flower stems from a central clump.
The flower stems grow beyond the leaves reaching up to the height of 5’ feet and bear spikes/ inflorescences of feathery flowers.
The plumes have a pinkish-purple tinge and last till the fall; the long bloom time is another reason for the plant’s popularity.
The seed heads initially have a golden color, but turn tan when they get mature.
The seeds are winter hardy, but sterile, which means the plant cannot self-seed.
Light & Temperature
Feather reed grass grows best in full sun but also grows well in partial shade.
In fact, it appreciates part shade in very hot weather.
If you live in an area where the weather tends to get really hot in summers, make sure you plant Calamagrostis acutiflora in partial shade and water it regularly because excessive heat and low moisture levels can cause the plant to enter summer dormancy.
However, be careful to not plant reed grass in full shade too as it will affect both its size and form – the plants grown in full shade tend to be smaller and a bit floppy.
The plant is winter hardy to USDA hardiness zones 5 to 9 and sometimes also referred to as cool-season grass.
Watering and Feeding
While the plant prefers moderate watering and moist soil, it can easily tolerate wet soils too.
Once established, the grass hybrid also becomes drought-tolerant.
On average, watering twice a week is enough for the feather reed grass.
Soil & Transplanting
The grass grows best in moist, well-draining and humus-rich (fertile) soil, but can tolerate a wide range of soils; it even grows in wet, compacted, and clay soils, which most plants cannot stand.
Amending the soil with compost before planting ensures maximum growth and large plants.
Grooming and Maintenance
Feather reed grass is a low-maintenance hybrid, but benefits from spring pruning.
Cut back the plant to about 4” to 5” inches above the ground, in early spring, to encourage new growth.
Cut the clumps back to the ground in late winter to promote new growth in the spring.
Propagating Calamagrostis x Acutiflora
While feather reed grass produces seed, they are sterile and hence, cannot be used for propagation.
The best method to propagate this Calamagrostis hybrid is through plant division.
Divide C. acutiflora in fall or spring.
For best results, choose a single mature clump and make sure the divisions have about 5 to 6 growing points.
This ensures flowering in the first year; smaller divisions can take two years to bloom.
Calamagrostis x Acutiflora Pest or Diseases
While the feather reed grass isn’t susceptible to any serious pest infestations or diseases, watch out for rust, especially after the rainy season.
These ornamental grasses also attract birds but are deer and rabbit resistant.
Feather Reed Grass Uses
Feather reed grass is an ornamental plant highly prized for its undemanding nature, ease of growth, attractive green foliage color, early blooming, and long-lasting plumes.
Due to its distinctive shape and growing pattern, the plant makes an excellent focal point in gardens and is also a popular choice for borders and narrow spaces in landscapes.
It also makes a wonderful backdrop for flowering plants and is also widely grown at the banks of ponds and streams.
The feathery plumes of C. acutiflora are showy and hence, used as cut flowers, in both fresh and dried forms, in flower arrangements.