Helictotrichon sempervirens, or blue oat grass, is a species of flowering plant in the Poaceae family of true grasses, native to central and southwest European grasslands. It is a bunchgrass often used as an ornamental grass in garden design and landscaping.
The foliage is pale green with a tinge of blue. It grows in an arching shape, up to 140 cm (55 in) tall by 60 cm (24 in) wide. The grass blooms with pale blue-green flowers in May to August. The plant is an evergreen perennial, although with summer drought stress semi-dormancy occurs. The Latin name sempervirens literally means "immortal" but in botany means "evergreen".
This plant has gained the Royal Horticultural Society's Award of Garden Merit.