Helictotrichon sempervirens, sometimes known as blue oat grass, is a clump-forming cool-season grass with steel-blue leaves. It is a beautiful plant that looks excellent in any garden.
It was awarded the Royal Horticultural Society’s Award of Garden Merit in 1993 and was named one of the Great Plant Picks in 2004. The neat, bristly mounds create an attractive ornamental plant. It’s similar to blue fescue cultivars, but taller and with thicker blades.
The genus name is derived from the Greek words helictos (twisted) and trichos (hair).
General Information
Blue oat grass grows 2 to 3 inches tall and spreads similarly. Foliage clusters grow to 2 inches, and blooming stems grow to 3 inches. The steel-blue leaf blades, which can reach up to 18 inches in length, are incredibly thin and spiky and form a rounded, porcupine-like cluster.
Spikelets of bluish-brown flowers appear in June on long stems rising high above the leaf cluster, arranged in open, one-sided panicles arching at the top. By fall, the flower spikelets have turned into a golden wheat color.
Care and Maintenance
Plant blue oat grass in full sun, although it can tolerate a little shade. It needs dry soil with adequate drainage. Winter survival needs well-drained soil. Although it favors moist soil, it will grow in both sandy and heavy clay soils, as long as the winters are not too wet.
The leaves are evergreen in warmer locations but die back in cold climates. Remove the old foliage with a rake or trim it back close to the ground in late winter. Except for crown rot, which develops in poorly drained soils, this plant has no serious insect pests or illnesses.
Blue oat grass may be propagated by division or seed in the spring. Sow new seed in late summer, maintain it in a cold frame throughout the winter, and it should germinate in the spring.
How to Use It in Landscapes
This little decorative grass has a unique color and texture. It’s a beautiful addition to a perennial border, especially as a contrast to plants with green leaves. Grow it in bulk for a fine-textured drift, or try it in a container as a single accent plant in a smaller garden or rock garden. Blue oat grass looks great in a row beside a sidewalk or in front of a shrub border.
Companion Plants
There are a number of great companion plants that accentuate the distinctive color and texture of blue oat grass. Combine it with the plants listed here to create an aromatic, drought-resistant, and even salt-tolerant garden.
Wild Thyme (Thymus Serpyllum)
Wild thyme, also called creeping thyme, is a low-growing, crawling, woody evergreen that stays small. It’s generally used as a decorative groundcover. The leaves of the plant are fragrant, although they are not often utilized in cooking. It stands 2 to 3 inches tall and varies in width from 3 to 12 inches. Northern Europe, western Asia, and northern Africa are all home to creeping thyme.
This hairy and prostrate variety thrives in sandy, gritty, or rocky soil, preferring full sun and tolerating poor soil. It can withstand drought and thrives even if it receives little water. During mild winters, it will stay evergreen.
The blooms are little tubular bell-shaped blossoms that range in color from deep pink to purple. From June through September, the blossoms develop on erect stalks. The nectar of the blossoms attracts bees and butterflies, and the plant is resistant to deer and rabbits.
Siberian Irises (Iris Sibirica)
Siberian irises feature strappy, sword-like foliage, just like other irises, but the leaves of Siberian iris are particularly appealing. Their texture resembles that of an ornamental grass. Siberian irises are also cold-hardier than other bearded irises, living happily in zone 3 gardens.
Blooms are mainly blue or blue-violet, although cultivars with yellow, white, pink, and red flowers are also available. The blooms are beautiful and have an elegant form, even if they aren’t very huge by iris standards.
Siberian iris is a perennial flower that blooms for many years. The blossoms feature three petals on top and three falls (drooping petals) below. Siberian iris plants may grow to be as little as 12 inches or as big as 3 feet tall.
Plant Siberian irises in late summer or fall to get the best flowers. If you plant Siberian irises in the spring, don’t anticipate flowers in the same year.
Lavender (Lavandula Angustifolia)
With its aromatic leaves and delightfully scented flower spikes, English lavender (lavandula angustifolia) is frequently misidentified as an herb. Instead, it is an herbaceous perennial with a semi-woody growth style.
This plant grows to be 2 to 3 feet tall, with thin gray-green leaves on square stalks that are about 2 inches long. The leaves may remain evergreen in warmer areas. Lavender grows at a modest pace throughout the warm season, as its woody base gradually expands and fresh stem development reaches several inches.
English lavender prefers full-sun locations. Plants grown in shady areas tend to become leggy and produce fewer flowers. However, in really hot areas, the plants will benefit from some afternoon shade. For the first week, young plants should be watered every other day. Once established, they are drought tolerant. Too much water may limit their capacity to bloom.
English lavender adds a splash of color to the garden in the middle of the summer and is popular in perennial borders, rock gardens, herb gardens, and small gardens. Because of its medium height, it’s ideal for the middle row of a beautiful border with shorter annual flowers in the front and taller shrubs or trees in the rear. It also looks good when massed and is sometimes used as a low hedge.
Blanket Flowers (Gaillardia)
The blanket flower is a perennial with daisy-like blossoms that is simple to cultivate. The plant grows in a slow-growing mound, and the popular name may reflect how it spreads and covers an area. At maturity, the plant reaches a height of approximately 24 inches and a spread of around 20 inches.
Once established, this sun-loving prairie native with daisy-like blooms requires little maintenance and provides months of continuous blossoms from late spring through autumn. Plant in a location with plenty of sunlight and excellent air movement.
Until the plants are established, keep the soil equally wet. Drought tolerance is high in mature plants, and they need little water. If the weather is hot and dry, water once or twice a week. Overwatering may result in root rot and fungal disease.
Powdery mildew, aster yellows, and fungal leaf spot are some of the diseases the plant may contract. Powdery mildew may be avoided by planting in a location with excellent air circulation. But when planted in ideal conditions, blanket flowers pose little challenges.
California Lilac (Ceanothus)
California lilac (ceanothus) is a vivid, gorgeous blooming shrub native to North America that may be found growing wild across the western United States. California lilac is not a real lilac of the syringa genus, but it does produce very fragrant blossoms from late spring to early summer.
Lilacs from California come in a variety of shapes that may be used in the landscape. Some are tall bushes with a height of 8 to 9 feet; while others are compact, low-growing groundcovers with a height of less than 6 inches. Plants feature tiny to medium glossy green leaves that contrast with the brilliant light-blue blooms.
Ceanothus is a simple plant to cultivate in the appropriate spot. It’s best to plant against a south-facing wall, as it needs protection from strong winds and harsh frosts. Once grown, most cultivars need full sun, well-drained soil, and little to no water. In the hotter southern areas, afternoon shade might be beneficial. However, too much shade will result in substandard flowers.
California lilacs need frequent, thorough watering when they are first planted, but once established, they are drought-tolerant and thrive in desert circumstances. They may need supplemental watering during extended hot, dry periods to sustain good growth and blooms. But generally, they don’t like being watered if they don’t have to.
