Trachyspermum ammi aka Ajowan Caraway

Trachyspermum ammi is an annual herb in the carrot family, Apiaceae. Its common names include ajwain and ajowan. Its native range runs from Iraq through Central Asia to Myanmar. It is not native to Britain or Ireland. Growers raise it as a spice crop across southern Asia. It grows on damp ground and suits climates with hot summers. People also grow it in tropical and subtropical regions.

The plant has an upright form, branched stems, and a strong scent. PFAF gives a garden height of about 2 feet (0.6 metres). It gives a spread of about 1.3 feet (0.4 metres). Useful Tropical Plants reports heights reaching 5.2 feet (1.6 metres). This taller range contrasts with both sources' listed height of 2 feet (0.6 metres). The plant flowers from July to August in the PFAF account. Its seeds also ripen during those months. Each flower has both male and female parts. Bees visit the flowers, and the plant is self-fertile.

Ajwain needs full sun and moist soil; it cannot grow in shade. It prefers loam that is not too heavy. It can also grow in sandy or clay soils. Mildly acid, neutral, and mildly alkaline soils are suitable. Useful Tropical Plants gives a preferred pH of 6.5–7. Soils used for wet rice can favour leaves over flowers. The plant is frost tender. PFAF suggests trying it as a spring-sown annual in Britain. Its seed-sowing guidance is tentative, rather than a proven local method. It suggests planting greenhouse-grown seedlings out after the last expected frost.

The aromatic fruits add a sharp flavour to savoury food. Cooks use them in curries, pulse dishes, breads, and pastry snacks. The seeds also yield an essential oil used in perfumes. That oil contains thymol and has reported antiseptic properties. Traditional medicine uses the seeds for digestive and breathing complaints. These include indigestion, wind, coughs, and asthma. Sources also record use for joint pain and fluid retention. Ripe seeds are dried for storage or distilled for oil.

Ajwain fits cultivated beds where gardeners can grow a scented spice crop. Its flowers provide a resource for bees. PFAF reports no weed potential for this species. Both plant-use sources list no known hazards. This does not establish safety for every use or dose. The supplied accounts name no specific pests or diseases.