Sisyrinchium californicum aka Golden Blue Eyed Grass

Sisyrinchium californicum belongs to the iris family, Iridaceae. Its names include golden-eyed grass and yellow-eyed grass. Its native range runs from Vancouver Island into the western United States. It grows in temperate regions and is not native to Britain or Ireland. This grass-like plant is a perennial, though individual plants can be short-lived. It forms clumps and keeps some leaves through winter.

The narrow, sword-shaped leaves have a grey-green colour. They reach about 0.5 feet [0.15 metres] long. Broad wings run along the upright flower stems. These stems can reach 2 feet [0.6 metres] tall. The RHS gives a mature height of 1.6–3.3 feet [0.5–1 metre]. Its stated spread is 0.3–1.6 feet [0.1–0.5 metres]. Plants take two to five years to reach full size. The leaves form a low base beneath the taller flowering stems.

Bright yellow flowers open in a sequence along the stems. Each has a star shape with brown veins. Missouri Botanical Garden lists flowering from May to June. The RHS describes its flowering season more broadly as summer. The blooms provide a clear display above the grey-green foliage. Plants set seed freely, so new seedlings can replace short-lived clumps. This habit can also make the plant a nuisance in gardens.

Grow this species in full sun with moist to wet soil. The RHS recommends boggy ground and accepts poorly drained sites. Loam and clay are suitable, across acid, neutral, and alkaline conditions. Choose a sheltered site facing south or west. A pond shelf offers another option, using an aquatic planting basket. Fill the basket with loam or a soil mix made for aquatic plants. The RHS rates it H4 for UK hardiness. Missouri Botanical Garden lists USDA zones 8–10. In St. Louis, it recommends growing the plant as an annual.

Use it beside ponds, in bog gardens, or in moist water gardens. It also suits informal borders, cottage gardens, and native plant areas. Border fronts and rock gardens offer other uses where moisture suits it. Coastal gardens are another suggested setting. No routine pruning is needed. Raise new plants from seed or divide existing clumps. Both horticultural sources report few pest or disease concerns.