Metrosideros robusta aka Northern Rata

Metrosideros robusta, or northern rata, is an evergreen tree from New Zealand. It belongs to the myrtle family, Myrtaceae. Its range includes both the North and South Islands. It grows in coastal forests and lower mountain forests. The recorded range reaches south to about 42°30′ south. It often starts life as an epiphyte on another tree. Its roots grow down through moss around the host.

Plants For A Future gives a height of 20 feet (6 metres). It lists a spread of 49 feet (15 metres). These figures describe a tree much wider than it is tall. In Britain, cold limits its growth to a small shrub. It keeps its leaves throughout the year. Its flowers have both male and female organs. Bees pollinate them, and the plant also draws wildlife. The source lists August as its flowering month.

Choose a sunny site, since this species cannot grow in shade. It needs moist soil that drains well but holds some water. Sandy, loamy and clay soils can all suit it. It prefers lime-free soil, though it tolerates some lime. Shallow soil over chalk does not suit it. The listed pH range runs from mildly acid to mildly alkaline. It withstands exposed coastal conditions, making it useful near the sea. Frost is a more serious limit than sea exposure. In Britain, outdoor plants succeed only in the mildest places. Plants For A Future lists USDA zones 8–11, yet calls it frost tender.

Garden uses include hedges and sunny edges of woodland gardens. Its value comes from its ornamental appeal and wildlife interest. Hedges can serve in exposed seaside sites. The wood is dense, hard, heavy and durable. Recorded uses include bridges and carriages. The flowers provide edible nectar. This is the only edible part listed by the source. Plants For A Future reports no known hazards or medicinal uses. That does not establish safety for every use or consumer.

Propagation options include spring-sown seed and cuttings of half-ripe wood. Seeds need a warm greenhouse and a light covering. Young plants need greenhouse shelter for their first winter. Plant them outdoors after the last expected frost. Give them cold protection through their first winter outside.