Narrow-leaf blue-eyed grass (Sisyrinchium angustifolium) is a flowering plant species that grows along shorelines, meadows, and sparse woods. Narrow-leaf blue-eyed grass is also called Pointed Blue-Eyed Grass, Stout Blue-Eyed Grass, and Bermuda Blue-Eyed Grass.
This is a native plant that is often found in large colonies in moist meadow areas and along river banks. It is a relatively fast-growing plant, though it may take two seasons to flower if you plant it from seeds.
I. Appearance and Characteristics
Sisyrinchium angustifolium, commonly known as narrow-leaf blue-eyed-grass, is a herbaceous perennial growing from rhizomes, native to moist meadow and open woodland. It is the most common blue-eyed grass of the eastern United States, and is also cultivated as an ornamental.
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.
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.
II. How to Grow and Care
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
Blue-eyed grass performs best in moist soils. In native locations, it is often found in damp meadows and along streams, and it will soon decline if soil is allowed to dry out for too long. It is best to water in the early morning hours, and during dry hot periods, you may need to water daily, especially if the plants are growing in less-than-ideal conditions. This plant normally will do well with the standard “1 inch per week” (rainfall and/or irrigation), but this can vary considerably depending on soil composition, temperatures, and other factors.
Applying mulch is normally a good way to preserve soil moisture, but in the case of blue-eyed grass, mulch covering the root crowns can encourage rot, so make sure to keep mulch and compost well away from the plant leaves and stems.
Soil
Blue-eyed grass does best in poor to average soil, but it must be moist and well-draining. It prefers an acidic or neutral soil pH of 5.0 to 7.0. Soil that is very rich is not ideal for these plants, causing a lanky habit.
Fertilizing
An occasional application of compost will be sufficient to improve soil, but even that is often unnecessary. Chemical fertilizers should not be used, as the plant prefers poor soil conditions. Over-fertilizing can result in lanky plants.
Pruning
Colonies of blue-eyed grass can be shorn back after blooming is complete to prevent unwanted self-seeding. Some gardeners like to deadhead the spent flowers to promote new buds and a longer bloom period, but it is not essential.
Propagation
New plants are easy to propagate by digging up and dividing root clumps in the spring. Here’s how:
- Use a shovel or trowel to dig up an entire intact clump of blue-eyed grass in the spring, as new growth is just beginning. Shake loose most of the soil, or spray with a hose to remove the soil.
- Gently tug apart the root clump into sections. Each section should have at least three or four growth shoots.
- Replant the sections in the desired locations, and water well until new growth is well established.
- Blue-eyed grass responds best to being divided in this way every two or three years to rejuvenate the clump, but if your goal is simply propagation, you can also simply dig up small offset plants around the mother plant and transplant them into new locations. Self-seeded volunteer plants can also be transplanted in this way.
How to Grow from Seed
If you collect seeds from plants, remember that they need cold moist stratification in order to germinate. Simply scatter the seeds over the area where you want them to grow in the fall and let the winter cold provide the necessary stratification. If you prefer to start them indoors in late winter, then store the seeds in the refrigerator for six weeks before planting them in small pots, just barely covered with moist potting mix (they need light in order to germinate). Keep the planted seeds in a bright location between 50 and 60 degrees until they germinate and sprout. Plants started from seeds may not flower until their second season, so be patient.
Overwintering
These hardy wildflowers need no particular winter protection, but you may want to cut down the plants to remove seed heads, which can cause undesirable self-seeding. But leave the seed heads in place if you want to attract birds.
Pests and 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.
How to Get to Bloom
Blue-eyed grass is normally quite generous with its flowers, provided it is getting plenty of sun and moisture. But keep these elements in mind for maximum flower production:
- Blue-eyed grass prefers a relatively lean soil, and it may paradoxically resist blooming if growing in soil that is too rich. If your plants fail to bloom, try withholding fertilizer to see if this helps. Even excessive mulch can make the soil too rich, so neglect is often the best strategy for robust blooming.
- Blooming may slow down if plants become overly crowded, so lifting and dividing the plants every two or three years may help keep them flowering.
- Deadheading spent flowers may also prompt the plant into a longer bloom period, since it nudges the plant into producing additional flower buds.
III. Uses and Benefits
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.
