Weed of the Month – Blue-eyed grass

Blue-eyed grass (Sisyrinchium angustifolium) is a beautiful native plant in the iris family. This perennial plant looks very similar to thicker bladed turfgrasses and can survive in the lawn without detection until it blooms in April. This plant thrives in moist, well-drained soils. Although once established, it can occasionally tolerate dry conditions.

Blue-eyed grass tolerates shade to full sun conditions. The beautiful flowers attract bumble bees, blue azure butterflies, and other pollinators, and songbirds eat the seeds. This plant is an excellent addition to the front of landscape beds and pathways as it tops out between 6 to 8 inches tall.

Blue-eyed grass can become weedy in the lawn.

Blue-eyed grass can become weedy in the lawn.
Jackie Jordan, ©2022, Clemson Extension

However, blue-eyed grass can become weedy in the lawn. A few cultural controls can help to keep this plant in check. Blue-eyed grass is a short-lived perennial but quickly establishes from seed, so regular mowing can help to limit the spread. It is important to never remove more than 1/3 of the grass blades when mowing, or your turfgrass’ growth can become thin and stunted. This will weaken the lawn and create more opportunities for weeds to become established. To determine the correct mowing height for your lawn, see HGIC 1205, Mowing Lawns. It is also essential to keep lawn mower blades sharp so that grass doesn’t lose excessive moisture through transpiration. Sharpening your lawnmower blades at least once a season can help keep your lawn grass healthy and more drought tolerant.

Since blue-eyed grass thrives in moist soils, keeping your lawn cut at the recommended upper limit can increase the grasses’ drought tolerance. Deep and infrequent irrigation will also encourage greater drought tolerance. For more water-saving tips when irrigating your lawn, see HGIC 1207, Watering Lawns.

Soil compaction can cause the grass to become thin and the soil to retain excessive moisture, creating a more favorable environment for blue-eyed grass. Core aeration can help alleviate compaction, fuel growth of the turfgrass, and increase water infiltration into the soil. Core aeration should be performed from May through early June in warm-season lawns. For more information about aerating your yard, see HGIC 1200, Aerating Lawns.

If this document didn’t answer your questions, please contact HGIC at hgic@clemson.edu or 1-888-656-9988.

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