How to Plant and Grow Blue-Eyed Grass

Star-shaped, blue-purple flowers decorate blue-eyed grass (Sisyrinchium spp.) in spring and early summer. Although "grass" is in its name, blue-eyed grass is actually in the iris family. Its sturdy leaves remain green and upright throughout the growing season.

Blue-eyed grass complements a host of perennials. Plant it at the base of clematis as an easy-care groundcover. Partner it with New Zealand flax and enjoy the distinct textures of both plants' straplike leaves. Blue-eyed grass also pairs well with all types of roses; both plants grow well in loamy, well-drained soil.

Where to Plant Blue-Eyed Grass

A full-sun location for blue-eyed grass is ideal, but the plant can handle part shade. It grows best in loamy soil that drains well. Blue-eyed grass is a wonderful plant for edging a walkway or the front of a cottage garden border, where this compact perennial will grow in a slowly spreading clump. It is also a good choice for rock gardens and woodland gardens.

How and When to Plant Blue-Eyed Grass

Prior to planting, enrich the planting area with well-decomposed compost, mixing it into the soil in the planting hole and the surrounding area.

Plant nursery-grown transplants 18 to 24 inches apart in early spring in moist, well-draining soil. Water the plants regularly through the first growing season to promote a robust root system. Blanket the soil around plants with a 2-inch-thick layer of mulch to prevent soil moisture loss.

If you prefer to plant harvested seeds, sow them in the fall because they require cold stratification to germinate. (Commercial seeds come pre-stratified.) Barely cover them; they need light to germinate. If you plan to plant harvested seed in spring, put the seeds in the refrigerator for about six weeks before sowing them in small pots. Keep them in a bright, cool room. Seeds sown in spring produce plants that won't flower the first year.

Blue-Eyed Grass Care Tips

Light

An easy-to-grow plant, blue-eyed grass thrives in full sun or part shade.

Soil and Water

Blue-eyed grass prefers moist, well-drained soil. It produces a thick stand of healthy, dark green foliage when planted in soil that contains organic matter, but it is almost as happy in poor soil.

Temperature and Humidity

Blue-eyed grass tolerates temperatures that drop as low as 20°F and is drought-tolerant once established. The plant enjoys average humidity and tolerates low humidity.

Fertilizer

An annual application of compost is all this plant needs. Don't apply any commercial fertilizer; overfertilization causes the plants to become spindly.

Pruning

You may want to cut blue-eyed grass back to the ground after blooming has ended to prevent unwanted self-seeding. Plants benefit from being divided every few years in early spring to maintain vigorous growth.

Pests and Problems

Blue-eyed grass has no problems with most pests or diseases. Even deer leave it alone.

How to Propagate Blue-Eyed Grass

Blue-eyed grass can be propagated by division and seed.

Division: Dig around an established clump of blue-eyed grass using a spade or garden fork and lift it out of the soil. Shake the clump or spray it with a garden hose to wash away excess soil on the roots. Pull the clump into sections using your hands; each section must include roots and three or four shoots. Replant the sections immediately in prepared garden soil.

Seed: Wait until the seed pods of an established plant turn black and hard before harvesting them. They'll break open soon at this point, so be vigilant, or the tiny seeds will be lost. After you cut the pods, rub them between your fingers to release the seeds. These seeds must go through cold stratification, so plant them in the fall and let winter handle the stratification naturally, or put them in a refrigerator for about six weeks to chill them artificially. When ready to plant, broadcast them on a prepared bed but barely cover them. They require light to germinate.

Types of Blue-Eyed Grass

'Aunt May' Blue-Eyed Grass

Sisyrinchium striatum 'Aunt May' is a clump-former with clean gray-green iris-like leaves striped with cream. The pale yellow flowers cluster on 20-inch-tall zigzag stems. Zones 7-8

Narrowleaf Blue-Eyed Grass

Common narrowleaf blue-eyed grass (Sisyrinchium angustifolium) forms clumps of grassy foot-long leaves. Its winged and branched stems carry small clusters of bright blue flowers, yellow at the throat. Each lasts a single day, but there is a succession. Self-seeds freely. Grows to 18 inches tall and 6-12 inches wide. Zones 5-8

'Devon Skies' Blue-Eyed Grass

Sisyrinchium 'Devon Skies' bears a profusion of light blue flowers. It has exceptional tolerance for heat and humidity. This mighty miniature grows to 6 inches tall and spreads to 12 inches. Zones 5-9

Blue-Eyed Grass Companion Plants

Lupine

Lupine draws the eye skyward with its gorgeously colored and interestingly structured flower spikes. The bicolor Russell hybrids are the most popular type. Their large pea-like flowers come in amazing colors and combinations, clustered in long spikes on sturdy stems. Lupine prefers light, well-drained soil that is slightly acidic, and it does not tolerate heat or humidity well. It performs best in areas with cool summers, especially the Pacific Northwest.

Perennial Geranium

One of the longest bloomers in the garden, hardy geranium bears little flowers for months at a time. It produces jewel-tone, saucer-shaped flowers and mounds of handsome, lobed foliage. It needs full sun, but otherwise, it is a tough and reliable plant, thriving in a wide assortment of soils. Many of the best are hybrids. Perennial geraniums may form large colonies.

Iris

Named for the Greek goddess of the rainbow, iris comes in a rainbow of colors and many heights. All have the classic, impossibly intricate flowers. The flowers are constructed with three upright "standard" petals and three drooping "fall" petals, which are often different colors. The falls may be "bearded" or not. Some cultivars bloom a second time in late summer. Some species prefer alkaline soil, while others prefer acidic soil.

Rue

Play up the blue hues in the garden by pairing blue-eyed grass with the blue-green foliage of rue.

Perennial Salvia

Count on this sage to bloom through summer, when blue-eyed grass is taking a flower break.

Yarrow

Yarrow's yellow flowers and silver-gray foliage are a lovely contrast to blue-eyed grass.