Trigonella caerulea aka Blue Fenugreek

Trigonella caerulea is an annual plant in the pea family, Fabaceae. Its common names include blue fenugreek and sweet trefoil. Kew records it as a cultigen from the eastern Mediterranean. This means its recorded origin lies in cultivation. It grows in temperate climates and is not native to Britain or Ireland. It also occurs on disturbed ground and land used for crops.

The plant reaches about 2 feet [0.6 metres] in height. As an annual, it completes its life cycle within one year. Its leaves and young shoots provide food and flavouring. Flowers appear from July to August. Each flower has both male and female organs. Insects pollinate the flowers. The plant forms root nodules through a partnership with soil bacteria. These bacteria take nitrogen from the air for plant use.

Grow blue fenugreek in full sun, as it does not tolerate shade. It grows in ordinary garden soil but prefers well-drained loam. Sandy soils and clay are also suitable. It accepts mildly acid, neutral, and mildly alkaline conditions. Keep the soil moist while the plant grows. Cultivated beds suit this small annual crop. For propagation, soak seeds in warm water for 12 hours. Sow them in spring, directly where they will grow.

People grow this species in the Mediterranean for its edible leaves. Young seedlings can be eaten with oil and salt. The leaves and young plants can also be cooked. Dried leaves and flowers are ground for use in food. They add flavour and colour to bread and other dishes. Cooks also use them in soups and potato dishes. Boiled leaves yield an aromatic drink or flavour other tea. PFAF gives the plant a low edible-use rating of one out of five.

Its nitrogen-fixing roots offer another role in the garden. Some of the nitrogen can benefit plants growing nearby. At the season's end, cut away the above-ground remains. Leave the roots to break down and release their nitrogen. PFAF reports no known hazards and no known medicinal uses. This does not establish safety for every person or pet. PFAF does not flag the species as a weed risk. Its occurrence on disturbed land is still worth noting.