Anthoxanthum odoratum aka Sweet Vernal Grass

Anthoxanthum odoratum is also called sweet vernal grass. It belongs to the grass family. Its native range spans Macaronesia, Europe, northwestern Africa, and Mongolia. Britain and Ireland are part of its native range. It has spread beyond this range, across much of the United States. Wild plants grow in meadows, heaths, and moors. They also grow at woodland edges, on acid and alkaline soils.

This grass grows in the cool season and forms upright clumps. It has a short lifespan. Most sources call it a perennial, living for several years. Yet plants can act as annuals, living for one year. Garden plants reach about 1.6–3.3 feet [0.5–1 metre] tall. Clumps spread roughly 0.3–2 feet [0.1–0.6 metres] wide. The thin, flat leaves look pointed but feel soft. Some exceed 0.5 feet [0.15 metres] in length. Crush the leaves and they smell like cut clover. Dry leaves keep their scent. Sources disagree on whether leaves stay green through winter.

Thin flower spikes rise in spring and early summer. The flowers have brown, copper, or yellow tones. The spikes turn golden brown as they dry. This grass blooms early. Its pollen can cause hay fever. Its fruit is a small grain called a caryopsis. Coumarin gives the plant its hay-like scent. People once added it to hay and pasture mixes for scent. Cattle, though, find it poor eating.

Full sun suits it best, but it accepts dappled shade. It grows in clay, loam, sand, and chalk. Good drainage matters more than soil type or pH. Avoid ground that stays soaked with water. Plants accept dry to moist soil. Once settled in, they resist drought. RHS rates it H7. NC State lists USDA zones 5–9. It needs little care and no routine pruning. Let plants set seed to help replace short-lived clumps. Grow more plants from seed or by dividing clumps.

Garden uses include wildflower meadows, borders, lawns, and mass planting. People also grow it indoors and use its scent in potpourri. Native Americans used this grass to weave baskets. Sources report few pests or diseases. PFAF lists edible seeds and leaf tea, but warns of risks. Coumarin can harm blood clotting when people take it by mouth. NC State warns against eating dried plants. It rates the degree of human poisoning as low. Reports of use as medicine do not remove that risk.