Eucalyptus regnans aka Australian Oak

Eucalyptus regnans is a huge evergreen tree in the Myrtaceae family. Its common names include Australian mountain ash and giant gum. It comes from south-central and eastern Victoria, and Tasmania. It grows in mountains and valleys, often forming pure stands. Deep, rich soils support it in its native range. Snow falls in some parts of that range.

This tree needs space far beyond most home gardens. RHS describes trees reaching about 295 feet [90 metres] tall. Its garden size bands exceed 39 feet [12 metres] in height. The spread band exceeds 26 feet [8 metres]. These bands do not give a firm upper garden size. The tree has an upright form and can grow bushy. RHS gives a maturity period of ten to twenty years. Its scale suits parkland and only the largest gardens.

Rough, grey-brown bark stays on the trunk rather than peeling. Bark on the branches comes away in long strips. This reveals cream, green and grey bark beneath the surface. Both young and mature leaves are green and lance-shaped. The leaves remain on the tree through the year. Crushed leaves and stems give off eucalyptus and balsam scents. White flowers appear in autumn, adding a seasonal feature.

Grow this tree in full sun with shelter from wind. It does best in moist soil that drains well. RHS lists clay, loam and sand as suitable soil types. Mildly acid, neutral and mildly alkaline soils all suit it. Mature trees withstand cold better than young ones. Protect young trees from cold winds that dry them out. RHS rates its UK hardiness as H4. Plants For A Future lists USDA zones 8–11. Raise plants from seed in spring or summer. RHS gives a seed temperature of 13–18°C.

The tree can provide a strong feature in large landscapes. Its hard, durable wood has straight grain and works well. Uses include furniture, joinery, building work and paper pulp. Eucalyptus gall wasp and eucalyptus sucker may attack it. RHS also lists silver leaf, honey fungus and oedema. Plants For A Future records no known edible uses. It also records no known medicinal uses for this species. Its listed value lies instead in its wood.