How To Care For Blue-eyed Grass: Growing Sisyrinchium Angustifolium

Some people prefer to have grassy lawns, while others want gardens of beautiful flowers. But what if we told you it’s possible to have both (sort of)?

Sisyrinchium angustifolium (sis-ee-RINK-ee-um, an-gus-tee-FOH-lee-um) is a member of the Iridaceae or Iris family with a twist. 

Flowers of the Stout Blue-eyed Grass - Sisyrinchium AngustifoliumPin

Known as blue-eyed grass, this wildflower has leaves that make it resemble grass for much of the year, bursting into little, attractive flowers at the height of its growing season. Although its tidy foliage resembles grass, it’s not true grass.

Other common names include:

  • Common blue-eyed grass
  • Grass flower
  • Narrow-leaved blue-eyed grass
  • Stout blue-eyed grass

This North American perennial is mostly found in the central part of North America and in open woods, grassy roadsides, glades, moist meadows, and prairies. 

This native plant plays well with several popular garden plants, making this a great choice for those who want to go for that midwestern prairie feel.

Sisyrinchium Angustifolium Care

Size and Growth

Blue-eyed grass forms relatively short clumps, ranging from around 8” to 20” inches tall and roughly as wide.

There are several cultivars available, but all share the same narrow, upright leaf blades, which generally measure around 3/16” inches wide.

This dense, grass-like foliage continues to grow from its hardy rhizomes throughout the season, resulting in its common name.

Flowering and Fragrance

However, while this plant can easily pass for a type of grass throughout much of the year, at bloom time in late spring, small ½” inch-wide violet-blue flowers pop up, continuing into summer.

These little flowers appear in clumps on wiry branched stems a few inches above the grass-like blue-green foliage and have yellow centers.

Each petal is oval-shaped but with a tiny sharp point on end.

White and purple flowers have also been known to appear, especially in cultivars where the plant has been bred for these variations.

One important thing to note, however, is that Sisyrinchium plants are normally heavy bloomers, and problems with blooming are almost always a result of overcrowding or overly rich soil.

Unless you deadhead, the plant will produce little red berries in late summer through autumn that give way to black seed pods.

Light and Temperature

Blue-eyed grass is adapted for life in wide, open fields, so it absolutely thrives in full sun. Growing in locations with the full sun will result in more flowers and denser foliage.

Although it can tolerate light or partial shade, it will have less full and produce fewer blooms.

The exception to this is in harsher southern climates where the midday sun can easily dry out the soil.

In such cases, full sun in the morning or evening with a little light shade during the hottest part of the day can be beneficial.

Blue-eyed grass grows best in USDA hardiness zones 4 to 9. In most northern climates, it’s a common practice to insulate the plant with a layer of mulch during the winter if temperatures below freezing are expected.

However, although mulching can preserve soil moisture, be warned that covering the root crowns of this plant can increase its risk of developing rot.

Watering and Feeding

Watering may seem a little tricky with this plant at first, but it’s quite simple if you use the finger trick.

Simply stick your finger in the soil and water if the ground is dry ½” inch down.

Water slowly and stop when the ground begins to have trouble absorbing as fast as you’re watering.

One huge difference between this plant and both grasses and most other flowers is the fact that it doesn’t like fertilizer.

In fact, because of its preference for poorer soils, fertilizing could lead to lanky plants.

If you’re concerned about the soil quality, such as when you have other plants also growing in the same space, you can mix a little organic compost into the soil when dividing.

Soil and Transplanting

Blue-eyed grass performs well in sandy soil rich in organic matter and medium moisture. However, it’s also adapted to live in poor to average soils and did its best in these conditions.

An overly loamy soil can result in lanky growth.

While it likes moist soil conditions, you must ensure you use well-drained soil.

As for soil pH, this plant can handle a pretty wide range from 5.0 to 7.0, although anything below 6.0 will likely be too loamy for healthy growth.

You will want to uproot and divide this plant every 2 to 3 years.

How only will this allow you to propagate the plant, but the central portion of the rhizome will be nearing the end of its lifespan, so dividing can greatly extend the life of your blue-eyed grass?

Grooming and Maintenance

This is a very low-maintenance plant and can usually be left to do its thing.

However, some people like to deadhead to help encourage more blooms, even though the plant is self-cleaning (meaning it will drop spent heads on its own).

Additionally, it’s a common practice to cut the plant back to just above ground level once the blooming period has completely ended to prevent self-seeding.

How To Propagate Blue-Eyed Grass Plants

Blue-eyed grass can (and should) be divided regularly, giving you a perfect chance to propagate using the divided rhizomes. It’s best propagated by division in spring every 2 to 3 years. 

Additionally, this plant will self-seed if the flowers are allowed to run their course. However, you must cut the plant back to the ground to remove seed heads after blooming to prevent unwanted self-seeding.

It can also be started indoors in late winter by storing the seeds for six weeks in the refrigerator before planting them.

Narrow-Leaved Blue-Eyed Grass Pests Or Diseases

As a wildflower, this plant is used to living in vast fields where pests are common. However, while it has no special resistance, deer often ignore it for more woody plants.

Root rot is a possibility if you overwater the plant, and aphids are a potential issue, but otherwise, you’ll likely have little to no problems with this plant.

 There has not been any conclusive evidence as to whether consuming parts of this plant is harmful to humans or pets.

However, because it’s related to lilies (which are highly toxic), we suggest caution when growing this plant around curious mouths.

Cats will often eat grass if they aren’t feeling well because it can induce vomiting, which may make this plant more attractive to them.

Sisyrinchium Angustifolium Uses

As a wildflower resembling grass, this plant can be used in a wildflower, woodland, and cottage gardens while looking as great as a general groundcover.

Its short height makes it a perfect plant for accents along paths and borders, and the tiny flowers draw in all sorts of pollinators, including bumblebees, flies, and sweat bees.

Moreover, since Sisyrinchium plants grow well in moist locations, they make an excellent choice for rain gardens, slopes, and banks.

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