Blue Eyed Grass Plant Profile

Blue-Flowered Native That Is Easy to Grow

Blue eyed grass flowers in field.

Tammy Harding / Getty Images 

Blue eyed grass is not really a grass at all. The "grass" in its common name refers, instead, to its blade-shaped leaves. True grasses such as those you grow in your lawn belong to the Poaceae family, whereas this plant belongs to the iris family. This makes it a relative not only of those beautiful irises that you grow in your flower beds, but also of montbretia (Crocosmia) and northern blue flag (Iris versicolor).

Botanical Name Sisyrinchium angustifolium
Common Names  Blue eyed grass, blue-eyed grass, narrow-leaved blue eyed grass
Plant Type Herbaceous flowering perennial
Mature Size 1 to 2 feet in height
Sun Exposure Full sun to partial shade
Soil Type Must have good drainage
Soil pH Blue eyed grass is not fussy about soil pH.
Bloom Time Late spring
Flower Color Blue
Hardiness Zones 4 to 9
Native Area North America

How to Grow Blue Eyed Grass

Blue eyed grass is easy to grow. In fact, it will often self-seed. Cut it back after it is done flowering if you want to keep it from self-seeding and thereby restrict its spread. Divide blue eyed grass every 2 or 3 years to revitalize it. The plant is generally not bothered by insects or diseases, and even deer tend to leave it alone.

Light

Tolerant of light shade, blue eyed grass often flowers better when grown in full sun.

Soil

The ground that it is growing in must drain well.

Water

Blue eyed grass performs best in soils that are on the moist side.

Fertilizer

Blue eyed grass needs a soil of only average fertility. An occasional application of compost will be sufficient and may not even be necessary.

Close Relation: Prairie Blue Eyed Grass

Sisyrinchium campestre, commonly called "prairie blue eyed grass," is a similar plant. It differs from S. angustifolium in just a few ways:

  • It can have white, as well as blue flowers. And the blue flowers are a lighter blue (S. angustifolium has violet-blue flowers).
  • It is smaller, sometimes reaching only 6 inches high.
  • It is more cold-hardy (to zone 2).
  • Its native range is more restricted, as it is native only to central North America (the ranges of the two overlap, since the range of S. angustifolium includes not only eastern North America, but also central).
  • It also blooms about a month earlier in spring.

Based on the species name, angustifolium (which is Latin for "narrow"), you might guess that another difference is in the width of their respective leaves. But, in this case, angustifolium is something of a misnomer: There is not that much difference between the two in terms of leaf width. Another plant in this genus with a confusing name is white blue eyed grass (S. albidium), another native of eastern North America: It really does have white flowers (or, at best, pale blue flowers).

Features, Uses for Blue Eyed Grass in Landscaping

Do not be confused by its name: Despite having "grass" in its common name, blue eyed grass is grown more for its flowers than for the grass-like look of its leaves. A similar confusion exists with monkey grass (Liriope), which is not a true grass but rather a member of the asparagus family.

But, in spite of its use as a flowering plant (rather than as a foliage plant), the bloom of blue eyed grass is hardly spectacular. It measures only 1/2 across. The flower as 6 blue tepals and a yellow center (or "eye"). Further detracting from its value as an ornamental is the fact that the flowers tend to pucker up late in the day and do not re-open again until the following morning.

It is thus not surprising that blue eyed grass is valued mainly by enthusiasts of native-plant gardens in North America rather than by the general public. If you do not live in North America but just happen to like the look of the plant, rest assured that it naturalizes well.

But another virtue of the plant for those growing it in North America is that, as a native, it is easy to grow, having adapted so well to its local environment. As companions for blue eyed grass in your native-plant garden, consider these other perennials that do well in full sun:

Other uses for blue eyed grass include: