Onobrychis viciifolia aka Common Sainfoin

Onobrychis viciifolia, or sainfoin, belongs to the pea family, Fabaceae. This perennial wildflower is native to Britain and parts of Europe. Its range extends east to Siberia, the Caucasus and Iran. It grows in grassland over chalk and limestone. Other names include holy clover, esparcet and common sainfoin. Despite names such as French grass, it is not a grass.

The plant forms bushy clumps around 2.5 feet [0.75 metres] tall. Its green, pinnate leaves have several leaflets along a central stalk. The foliage dies back for winter. Upright flower spikes rise above the leaves from May to September. The pea-like blooms are pink to red, with darker stripes. Their nectar draws many kinds of bees. Stems may sprawl among nearby plants unless they have support. This loose form suits meadow planting and informal borders.

Give sainfoin full sun and soil that drains well. Chalk, sand and loam can suit it. It prefers a neutral to alkaline soil. It thrives even where the soil is poor. Once established, it withstands drought well. It can grow in dry to moist ground, provided drainage stays good. A sheltered spot facing south or west suits its needs. Plants may need a year to settle in. They reach maturity within two to five years. The RHS rates it H7 for cold hardiness. PFAF lists USDA zones 5–9.

Sainfoin suits wildlife gardens, cottage gardens and wildflower meadows. It fixes nitrogen and can help improve poor, light soils. Its deep taproots loosen lower soil layers and draw up minerals. An extensive root system also helps hold soil in place. Sow seed in spring, or divide established clumps in early spring. Remove spent flowers to prompt fresh growth, then trim after flowering. Avoid cutting too low, as damage to the raised taproot can kill plants.

Aphids, slugs and snails may attack sainfoin. Possible diseases include Fusarium wilt, sclerotinia, and root or crown rot. PFAF lists leaves as edible but gives food use a low rating. Its cited food report does not identify the part used. This leaves the evidence for eating the plant limited. PFAF records no known hazards and no known medicinal uses. That hazard entry does not establish safety for every person or pet.