Native to Europe & Asia (arundinacea & epigejos)
FIRST IMPRESSIONS: Calamagrostis x acutiflora 'Karl Foerster' is an extremely popular cool season perennial grass cultivar. During cool weather deep green foliage emerges and forms a robust 2-foot clump. In early spring, culms rise to 5’ bearing panicles of loose feathery mauve tinged flowers. Flowers and foliage are quite mobile, waving in the slightest breeze. The blooms mature into slender golden seed clusters. When the narrow upright grass is topped with erect flaxen grain clusters, plants are reminiscent of sheaves of wheat. This cultivar is easy to grow in full sun to part shade and average well drained soil.
HABITAT & HARDINESS: Famed German nurseryman Karl Foerster first noticed this plant in the Hamburg Botanic Garden. The plant was a chance seedling thought to be a natural cross between two Eurasian species - Calamagrostis epigejos and Calamagrostis arundinacea. Foerster listed this grass in his nursery catalog in 1939 and included it in his 1950 garden book. The cultivar was sold in Europe before arriving the U. S. from Denmark in 1964.
This grass is hardy from USDA Zones 4-7. Plants will survive in southern zones 8-9 but they need cold winters and are not reliable performers further south than Zone 7.
PLANT DESCRIPTION: Calamagrostis x acutiflora 'Karl Foerster' is a graceful perennial grass with a striking vertical habit.
In early spring culms arise from a low cluster of leaves. Plants soon display feathery flower panicles. Since this is a cool season grass it bloom much earlier than other grasses and has an amazingly long blooming period.
The new flowers have a rosy tinge but they quickly develop an amber color. They become more compact and slender as seed begin to form and hold their golden color into the winter.
Foliage can remain evergreen or even initiate growth when winters are mild.
Plants attain 5-6’ height with 2’ spread.
CULTURAL & MAINTENANCE NEEDS: This cultivar prospers in sun or part shade in moist well drained or dry soil. Plants tolerate heavy clay and compacted soil.
Low fertility results in shorter plants. In low nutrient soils, fertilizer may be need to be applied to encourage plants to attain full size.
This grass should be cut to the ground in late winter before new growth initiates. Plants should be divided every few years in early spring to prevent clumps from dying out in the center.
This hybrid is sterile so seed are not viable and cannot reseed.
LANDSCAPE USES: This plant is used as an Accent, Cut Flower, or in a Grouping or Mass Planting. It provides Erosion Control, Fall Color, Showy Blooms, Winter Interest and is a valuable component of Cottage Gardens, Deer Resistant Plantings, Rain Gardens, Water-wise Landscapes, Low Maintenance Plantings and Perennial Borders.
COMPANION & UNDERSTUDY PLANTS: Try pairing with Aster oblongifolius ‘Raydon’s Favorite’, Amsonia hubrichtii, Echinacea purpurea and Rudbeckia fulgida var. fulgida..
Calmagrostis brachytricha has similar cultural needs and can be substituted if needed.
TRIVIA: In 2001 Calamagrostis x acutiflora 'Karl Foerster' was the first ornamental grass to be chosen as the Perennial Plant of the Year by the Perennial Plant Association.