Helictotrichon sempervirens
Blue oat grass
Common names: Blue avena grass
At a glance
- Light
- Full sun
- Pot size
- from 10 l
- Lifespan
- Perennial
- Flowering
- Jun–Jul
- Hardiness
- Hardy
Photo: Sten Porse · CC BY-SA 3.0 · Source
Description
Helictotrichon sempervirens, commonly known as blue oat grass, is a tufted ornamental grass that retains its steel‑blue, narrow leaves throughout winter. It forms compact, half‑spherical clumps and provides a calm, blue contrast among flowering perennials. In summer, delicate yellow‑brown panicles rise above the foliage and sway in the wind. It thrives best in rock gardens, gravel beds, and Mediterranean plantings. The plant is non‑poisonous and safe for gardens with children and pets.
Care instructions
Plant blue oat grass in full sun on a warm site with well‑drained, slightly sandy soil; it does not tolerate wet conditions. Water only during extended dry spells after planting, then it tolerates low moisture well. In early spring (late February to mid‑March, week 9 to 11), trim the clumps hand‑wide and remove dead stems by hand rather than cutting. Divide larger clumps every few years in spring to keep them vigorous and prevent inward thinning. Pair it with varieties such as ‘Pendula’ for a cascading growth at the edge of a pond.
The care notes were machine-translated from German.
Garden year
FloweringJun–Jul
Soil & site
Soil pH
Soil type
well-drained, lean, sandy, lime-loving
Blue oat grass likes it dry and lean, just as it knows it from sunny steppes and rocky slopes. It will not forgive you heavy, waterlogged soils; the roots rot quickly there. It feels most at home in free-draining, sandy-gravelly soil with some lime, for example in a gravel or rock garden.
Feeding
Light feeder
This ornamental grass manages well with the nutrients in the soil and needs no additional feeding. Too much food is even rather bad for it, as the blades then go soft and fall apart. A thin dose of compost in spring is entirely sufficient as a gesture if the soil is very depleted.
Overwintering
Blue oat grass is hardy in Central Europe and gets through the cold season outdoors without protection. Do not cut it back in autumn; the old foliage protects the heart of the plant from frost and wet. Only in early spring, shortly before new growth, do you comb the old blades out with your fingers or a rake.
Propagation
Methods
- From seed
- Division
The easiest way is to divide larger clumps into several pieces with a spade in spring and plant them straight away in their new place. Each division should bring some roots with it, and then it keeps growing reliably. Sowing is also possible, but it takes longer until a lovely blue-grey clump forms. Keep the young plants moderately moist in the first weeks, without drowning them.
For your garden
Grow Blue oat grass yourself
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