Feather reed grass (Calamagrostis x acutiflora) is a popular perennial ornamental grass that comes from a hybrid cross between Calamagrostis arundinacea and Calamagrostis epigejos. Unlike many other grasses that tend to flop after they bloom, feather reed grass looks tidy all year round. It grows in dense clumps of erect, narrow, green leaves that can reach around 3 feet long. Pinkish-purple, feathery flower spikes rise a couple feet above the leaves in the summertime and gradually turn to golden seeds, which can persist into winter. Because the plant is a hybrid, the seeds are sterile, so you won’t have problems with your feather reed grass spreading invasively. The ornamental grass has a moderate growth rate and can be planted in the spring or fall.
|Botanical Name||Calamagrostis x acutiflora|
|Common Names||Feather reed grass, reed grass|
|Mature Size||3–5 ft. tall, 1.5–2.5 ft. wide|
|Soil Type||Rich, moist|
|Soil pH||Acidic, neutral, alkaline|
|Bloom Time||Summer, fall|
|Hardiness Zones||5–9 (USDA)|
|Native Area||Europe, Asia|
Feather Reed Grass Care
Feather reed grass is typically planted from nursery-grown seedlings, not seeds. Plant it in the ground or a container at the same depth it was growing in the nursery container. Once established, this ornamental grass is fairly low maintenance. It rarely has issues with pests or diseases. But watch out for fungal rust, which appears as discoloration on the foliage and can arise from long rainy spells. A fungicide can be helpful, but prevention by ensuring good air circulation around the grass is key.
Regular maintenance will primarily be watering when the soil begins to dry out. Then, plan to cut the grass to the ground as part of your garden cleanup after winter. And feed it annually if your soil is poor.
Feather reed grass grows best in full sun, meaning at least six hours of direct sunlight on most days. However, it does appreciate some shade from harsh afternoon sun, especially in the warmer parts of its growing zones. But if it gets too much shade, it won’t flower as profusely, the leaves can get floppy, and the plant overall will be on the smaller side.
The grass is tolerant of a wide range of soil types. But it does best in a rich, consistently moist, well-draining soil. It can tolerate heavy clay soil and wet areas of the landscape, such as on the bank of a pond.
Feather reed grass has moderate water needs. So water it whenever the soil feels dry about an inch down. Mature plants do have some drought tolerance, but even moisture is best. Soil that is too dry will result in a plant that doesn’t reach its full growth potential.
Temperature and Humidity
The plant is regarded as a cool-season grass and doesn't care for intense heat. It should be planted when the temperature is below 75 degrees Fahrenheit, so it has time to establish a root system to take in moisture before the hot weather arrives. Feather reed grass can survive temperatures below freezing. However, in the northern parts of its growing zones it can be helpful to put a layer of mulch over the plant to insulate it over the winter. Humidity typically isn’t an issue for feather reed grass, as long as there is good air circulation around the plant.
Feather reed grass typically doesn’t require any supplemental fertilizer. But organic mulch and compost mixed into the soil both can be beneficial to add nutrients. If you have poor soil, apply a balanced all-purpose plant food in the spring following label instructions.
Because the plant still looks tidy into winter and can provide interest with the seed heads, most growers wait until late winter or early spring to cut their feather reed grass to the ground. Do so just before new growth appears, so you don’t accidentally prune any new foliage. Use pruning shears or a hedge trimmer to cut the previous season’s growth to a few inches above the soil line.
Propagating Feather Reed Grass
While feather reed grass won’t spread uncontrollably in the landscape, a clump of it will continue to get larger. Eventually the clump will need to be divided once it’s so large that sunlight and air flow won’t reach its center. This generally will occur every three to five years, and spring is the best time to divide. Simply dig up the clump, and gently pull it apart, keeping as many roots intact as possible. Then, replant your divided clumps wherever you’d like.
Feather Reed Grass Varieties
There are a few popular varieties of feather reed grass:
- Calamagrostis x acutiflora 'Karl Foerster' is known for its neat vertical growth habit and pinkish-purple to reddish-bronze flower spikes.
- Calamagrostis x acutiflora 'Overdam' has white variegated leaves and white flowers, and it grows 2 to 3 feet tall.
- Calamagrostis x acutiflora 'Avalanche' has yellow variegated leaves and golden-brown flowers and also grows 2 to 3 feet tall.