Sainfoin

Sainfoin (Onobrychis viciifolia) is a deep-rooted, perennial legume in the Fabaceae family, historically prized as a forage crop in temperate regions. It produces attractive pink flower spikes and fixes atmospheric nitrogen, making it an excellent green manure and soil improver. The plant thrives in well-drained, calcareous or sandy soils in full sun and tolerates drought once established. Its anthelmintic properties have recently renewed scientific interest in the species.

Growing

Sow directly into well-prepared, weed-free soil once soil temperature reaches 5 °C. Sow seeds 2–3 cm deep in rows spaced 15 cm apart, or broadcast for green manure cover. Seeds may be large and should be pressed firmly into the seedbed for good contact. Germination occurs within 7–21 days. The plant establishes slowly in the first year but becomes vigorous and self-sustaining from the second year onward.

Care

Once established, sainfoin requires minimal intervention. Water during prolonged dry spells in the establishment year; mature plants tolerate drought well. Avoid waterlogged or acidic soils. Do not over-fertilise with nitrogen — as a legume it fixes its own. Cut back after flowering to encourage fresh growth and prevent excessive self-seeding if not desired.

Harvest

For green manure, cut and incorporate into the soil when plants reach full flower but before seed set. For forage or biomass, cut when the majority of flowers are open and before the lower leaves begin to yellow. Cut at 5–8 cm above ground to allow regrowth. The plant can yield two to three cuts per growing season once fully established.

In the kitchen

Sainfoin is not typically grown as a food crop for human consumption. The flowers are edible and can be used as a decorative garnish in salads. The plant is primarily grown to enrich soil, support pollinators, and as animal forage.

Storing

Fresh-cut material for green manure should be incorporated into soil immediately. If harvested as hay or forage, dry thoroughly in a well-ventilated location until moisture content drops below 15% before baling or storing in a dry, covered space.