Cneorum tricoccon aka Spurge Olive

Cneorum tricoccon is a small evergreen shrub from the western Mediterranean. Its common names include spurge olive and smooth widow wail. The RHS places it in the rue family, Rutaceae. It is not native to Britain or Ireland. In the wild, it grows on rocky slopes, often over limestone. Its leaves stay on the plant throughout the year.

Plants For A Future gives its height as 2 feet [0.6 metres]. A shrub grown at Kew also reached that height. This makes it a low shrub rather than a tall screen. The supplied species account gives no mature spread. It flowers from June to July, with seeds ripening during August and September. Each flower has both male and female organs. The evidence does not name its pollinators.

Choose a sunny site with light soil that drains well. The species account says it cannot grow in shade. Sandy soil suits it, and it accepts dry or moist ground. It tolerates mildly acid, neutral, and mildly alkaline soil. Its listed garden settings include planted beds and sunny woodland edges. Shade appears in one garden-location list, but conflicts with the stated light needs. A sunny position therefore has stronger support in the evidence.

Reports of cold tolerance differ, so the hardiness figures need care. Plants For A Future lists USDA zones 8–11. One cited report gives survival down to about −15°C. Another says it fails at Kew but grows in milder British areas. Yet the same account records a Kew shrub producing viable seed. For propagation, sow seed under glass from late winter to midsummer. Cover it lightly and keep the soil moist. Germination may take one to six months at 20°C. Keep seedlings under glass through their first winter. Plant out after the last expected frost. August cuttings of half-ripe wood offer another method. These also need frost-free winter shelter.

Plants For A Future records no known edible uses. Its food-use rating is zero out of five. It lists historical medicinal uses as a purgative and skin reddener. These records do not establish safe home use. The plant also contains tannins and has served as fuel. The source reports no known hazards, but gives no specific safety evidence. The supplied material names no pests or diseases. It also records no weed potential.