Ceanothus arboreus aka Feltleaf Ceanothus

Ceanothus arboreus is an evergreen shrub or small tree. It belongs to the buckthorn family, Rhamnaceae. Common names include Catalina ceanothus and Catalina mountain lilac. Its native range covers California’s Channel Islands and Guadalupe Island. It grows in chaparral scrub within a subtropical climate. It is not native to Britain or Ireland. The plant keeps its leaves throughout the year.

This species has a rounded or spreading form. Plants For A Future gives a height of 23 feet [7 metres]. It describes the growth rate as moderate. Blue flowers provide the main spring display. The same source lists flowering from April through August. Each flower has both male and female organs. The fruit forms a capsule that releases seeds with force. This can make the timing of seed collection important.

Choose a warm, sunny site with shelter from cold winds. The plant also accepts light shade. It needs well-drained soil and suits sandy or loamy ground. It grows in mildly acid, neutral, or mildly alkaline soil. Some lime is acceptable, but shallow chalk is unsuitable. Soil may be dry or moist. Plants For A Future lists USDA zones 8–10. It reports cold tolerance near 23°F [−5°C]. In Britain, it suits the milder areas. Plant it in its lasting site while still small. Its roots do not take disturbance well. Avoid heavy pruning, including cuts through wood thicker than a pencil.

Garden uses include hedges, containers, rock gardens, and coastal sites. It can also help control erosion. A sunny woodland edge offers another possible setting. The plant can fix nitrogen. Its flowers yield a green dye. All parts contain saponins, which form lather in water. Crushed material can therefore serve as a mild soap. Flowers and developing seed cases are useful sources. The lather removes dirt but works poorly on oils. Flower-based soap can leave a scent on the skin.

Plants For A Future records no known edible or medicinal uses. It also lists no known hazards. That statement does not establish safety for eating or pets. The source does not flag this species as weedy. Seeds can retain their ability to sprout during long storage. Fresh seed is best sown once ripe, in a cold frame. Stored seed may need soaking and a cold treatment.