Blue oat grass, Helictotrichon sempervirens, is a cool season,
clump-forming grass with steel-blue foliage. This is an award-winning plant for
any garden. It won the Award of Garden Merit from the Royal Horticultural
Society in 1993 and was selected for Great Plant Picks in 2004. The neat,
bristly mounds make an attractive ornamental plant. It is similar in appearance
to blue fescue (Festuca ovina glauca cultivars), but taller and with
sturdier blades.
Native to central and southwestern Europe, this perennial grass is hardy in
zones 3 or 4-8.The long, wiry leaves on arching stems are about ½ inch wide and
taper to a fine point. Under optimal conditions it grows about two feet tall and
three feet wide. Graceful flower plumes grow vertically from the center of the
plant. Pale blue flowers bloom on beige, one-sided panicles in midsummer. It
often does not consistently produce the attractive, arching four foot flower stems in more
northern areas where there is a shorter, cooler growing season. The leaves turn
light brown in autumn and persist through the winter.
This small ornamental grass has many landscape uses, with a color and texture
few plants have. It makes a nice addition to the perennial border, particularly
as a contrast to green-leaved plants. Use it as a single accent plant in the
smaller garden or rock garden, grow it in masses for a fine-textured drift, or
try it in a container. Blue oat grass makes a nice row along a walkway, or can
be added to the front of a shrub border. It combines well with Russian sage (Perovskia),
Salvia x sylvestris ‘Mainacht’ (‘May Night’), blanketflower (Gaillardia),
Sedum ‘Autumn Joy’ and other, more upright ornamental grasses. Use it to echo
the blue foliage or flowers of blue spruce, blue junipers or blue-flowering
perennials such as Campanula, lavender (Lavendula), or blue mist spirea (Caryopteris).
For a more dramatic effect, try combining it with plants with deep maroon
leaves.
Plant blue oat grass in full sun. Well-drained soil is essential for winter
survival. Although it prefers a moist soil, it will tolerate sandy as well as
heavy clay soils – as long as it does not remain too wet in winter. Evergreen in
milder climates, the leaves die back in Wisconsin winters; use a rake to remove
the old foliage or cut back close to the ground in late winter. This plant has
no significant insect pests or diseases other than crown rot that occurs in
poorly drained soils.
There are a few cultivars
Propagate blue oat grass by division in the spring or grow from seed. Sow fresh seed in late summer, keep over the winter in a cold frame, and they should germinate in spring.
– Susan Mahr, University of Wisconsin - Madison
