How To Grow Blue Oat Grass (Helictotrichon sempervirens) In Your Garden

Helictotrichon sempervirens, commonly known as Blue oat grass, belongs to the Poaceae family (monocotyledonous grasses) and is native to the grasslands of Southwest and central Europe.

This bunchgrass that is often used in garden design and landscaping as an ornamental grass. One of its main features are its attractive blue foliage.

Helictotrichon sempervirens makes for a great landscaping plant.
Helictotrichon sempervirens used as a border in a landscape, photograph by Matt Lavin, CC

Blue oat grass has the advantage that it is fairly easy to maintain.

This ornamental grass blooms as such in June and July (Northern Hemisphere) with flowers that are bluish-brown.

Its leaves are pale green with a blueish tinge, and it grows in an arching form.

It grows in full sun in dry to medium, well-drained soil with the best shades of blue color achieved in dryish soils.

Gardener's HQ Guide to Growing Helictotrichon sempervirens

Preferably, plant the grass between September and the end of November, or between March and the end of April.

At around this time, the temperature is usually not too low.

Use moderately fertile, well-drained soil with a neutral to slightly alkaline pH.

Bury the roots a couple of inches (5 cm) so that the foliage is even.

Close up of Blue Grass.
Close up of Blue Grass, Image by Drew Avery, CC

To avoid leaving a pocket of air, fill and pack the soil well around the plant.

After planting, water the blue oat grass amply.

For container grown Helictotrichon sempervirens, choose a pot that has a volume corresponding to that of the plant to avoid frequent watering. Use a mixture of soil and compost for container plants. Add gravel to provide proper drainage at the bottom of the pot.

In the first weeks after planting, water the plant regularly.

To minimize loss of water through evaporation, avoid watering on sunny afternoons.

If the plant is potted, check how damp the top layer of soil is by either looking at it or touching it using your finger.

However, if it hasn't rained in a month, make a point of watering the plant.

When pruning, remove leaves that have withered as they appear, and in the spring. Remove dead leaves and old stems that have flowered.

Blue oat grass is generally a pest-free plant but may be affected by rust in humid climates.

Helictotrichon sempervirens Saphirsprudel cultivar.
Helictotrichon sempervirens Saphirsprudel by F.D. Richards, CC.

Quick Growing and Care Guide

Scientific Name: Helictotrichon sempervirens

Common Name (s): Blue Oat Grass

Growing Zone (USA / UK Hardiness): USDA Zones 4 to 8 / Europe/ H7 – fully hardy.

Best Used For / Garden Location: Landscapes, Wild gardens, Rock gardens, Borders, En masse for Ground cover, Winter interest, Foundation plant.

Plant Details

Life Cycle / Plant Type: Perennial. Semi-evergreen.

Plant Height: 2 to 4 feet (60 cm to 1.3 m).

Plant Spread: 2 feet (60 cm).

Blooms: Early and mid-summer.

Flower Details: Showy, Blue-brown. One sided panicles, carried on arching stalks.

Leaf Foliage: Narrow leaf blades. Blue-grey.

Fruit: Panicles turn golden as they mature and produce seeds.

Helictotrichon sempervirens Panicles photograph by Matt Lavin, CC
Panicles photograph by Matt Lavin, CC

Growing Conditions and Location

Best Light Conditions: Full sun for best results, or partial shade.

Suitable Soil Types: Average. Neutral to Alkaline pH. Does not like clay soils.

Soil Moisture: Dry to medium, Good drainage.

Sowing, planting, and Propagation: Sow Helictotrichon seeds on the surface in spring as light is required for germination, which typically takes from 10 days to three months.

An easy way to generate more plants is to divide the root-ball of this grass in the middle of Spring.

Or established plants can be allowed to self-sow.

Space plants at about 30 to 45 cm (12 to 18 inches).

Care: Can be cut back towards the end of winter, or alternatively give then a raking over to remove decayed leaves.

Seedlings require adaquate watering during their growing period.

Blue Oat Grass used in a pathway border.
Blue Oat Grass by Matt Lavin, CC

Growing in pots and containers: Yes. Use a fairly large container.

Further Information

Miscellaneous: A tough plant that is tolerant of deer, drought, Salt, and does well in areas of Air pollution.

Can help to bring butterflies to the garden.

Cultivars and Varieties: Saphirsprudel / Sapphire: Wide leaf blades, More reliant blue colour.

Pendula: Purple flushed flowers.

Family: Poaceae (Grasses)

Closely Related Species: Helictotrichon pratense (Meadow Oat Grass).

Native: Central and southwest Europe.

References and Further Reading: Wisconsin Horticulture; This great PDF by the University of Florida Cooperative Extension Service, Guide to Ornamental Grasses by CORE.

Common Questions

Should Blue oat grass be cut back?

You may wish to remove unsightly decaying leaves by pruning in the autumn. Pruning may also help to rejuvenate the growth of struggling plants. Raking also gives good results, as this allows the plant to maintain its basic shape.

What is Blue Oat grass?

It is a true grass belonging to the Poaceae family. As it is a tough grass it makes a great plant to grow when landscaping a difficult area, such as places that get little rain or have abundant wildlife pests (rabbits and deer).

It can make a great coverage plant and also looks good as part of a rock garden.

How tall are Helictotrichon sempervirens?

Plants are typically about two or three feet (60 to 90 cm) high, but can reach a good foot (30 cm) higher in ideal conditions.

Blue Oat Grass Saphirsprudel
Blue Oat Grass Saphirsprudel by F.D. Richards, CC.

Is Blue oat grass invasive?

Helictotrichon sempervirens is not generally considered to be an invasive plant in N. America and is generally easy to care for and control.

The plant is clump forming and does not spread from rhizomes; this makes it pretty easy to control.

NB. Do not confuse with a similarly named Oat grass Leymus arenarius, which can be a pain to remove from the garden. This plant is more commonly known as Sand Ryegrass or Sea Lyme Grass and has vigorous growth.

I hope that you enjoyed this garden plant guide on how to grow Helictotrichon sempervirens. You may also enjoy the following grass growing guides: How to Grow Cloud Grass, Feather Grass, Draba plant, and Miscanthus plants.

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