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TREES & plants

Blue oat grass

Blue oat grass is a cool season clumping grass with blue foliage, attractive flowers and a mounded form.

This plant has some cultivated varieties. Go to list of cultivars.

Botanical name: 
Helictotrichon sempervirens
All Common Names: 
Blue oat grass
Family (English): 
Grass
Family (Botanic): 
Poaceae
Tree or Plant Type: 
  • Grass, 
  • Perennial
Native Locale: 
  • Non-native
Landscape Uses: 
  • Container, 
  • Foundation, 
  • Massing, 
  • Mixed border
Size Range: 
  • Large plant (more than 24 inches)
Light Exposure: 
  • Full sun (6 hrs direct light daily)
Hardiness Zones: 
  • Zone 4, 
  • Zone 5 (Chicago), 
  • Zone 6, 
  • Zone 7, 
  • Zone 8, 
  • Zone 9
Soil Preference: 
  • Moist, well-drained soil
Season of Interest: 
  • Early winter, 
  • Mid winter, 
  • Late winter, 
  • Early spring, 
  • Mid spring, 
  • Late spring, 
  • Early summer, 
  • Mid summer, 
  • Late summer, 
  • Early fall, 
  • Mid fall, 
  • Late fall
Flower Color & Fragrance: 
  • Blue
Shape or Form: 
  • Mounded, 
  • Upright
More Information: 

Size and Form

Blue oat grass grows as an upright tuft or mound, reaching a height 2 to 3 feet when in flower.

Plant Care

Best in full sun and a moist, well-drained soil.  Wet, clay soils may lead to root rot.  This grass does not tolerate hot, humid summers and flowering may be reduced under those conditions.  Good air circulation is needed to minimize rust (a fungal disease).

This is a cool season grass, so its most active growth occurs in spring and fall.  It will be semi-evergreen in winter and can act as winter interest.

Since this grass remains semi-evergreen through winter, it should not be cut back until early spring, before new growth begins.  At that time, it can be cut down to the ground if needed or simply trimmed to remove winter damage.

Disease, pests, and problems

Rust can occur in wet, humid conditions.

Native geographic location and habitat

Native to Europe and Asia

Leaf description

The metallic blue leaves are 1/4 to 1/8 inch wide and 12-18 inches long.  They remain blue all year.

Flower description

Flowering time is late spring into early summer.  The tiny, blue-white flowers are in oat-like clusters held on one side of the flower stalk.

Fruit description

The small fruit (caryopsis or grains) form in the oat-like clusters that held the flowers.  They are tan when mature.

Cultivars and their differences 

Saphirsprudel (Saphire Fountain) (Helictotrichon sempervirens 'Saphirsprudel'): This cultivar is more tolerant of heat and resistant to rust.  Steel blue leaves.

Helictotrichon sempervirens or Blue oat grass

We do not seem to have this in our living collection.