Eucalyptus johnstonii aka Johnston's Gum

Eucalyptus johnstonii is an evergreen tree in the myrtle family, Myrtaceae. People call it yellow gum or Johnston’s gum. It comes from south-central and south-eastern Tasmania, in Australia. Its home range has a temperate climate. In the wild, it grows on sandstone sites that drain poorly. Its reported height above sea level is 1,970–8,530 feet [600–2,600 metres]. It is not native to Britain or Ireland.

This tree grows fast and can reach 197 feet [60 metres]. This is its possible size, not a proven garden range. It keeps its leaves all year. Its flowers have both male and female organs. Bees pollinate the flowers, and the tree draws wildlife. The supplied species accounts do not state flower colour or season. Nor do they describe the bark, leaf shape or fruit.

Give this tree full sun; it cannot grow in shade. It prefers soil with a fair level of nutrients. The soil should hold moisture but drain well. Near-neutral soil suits it, but slight acidity or alkalinity is fine. It also copes with poor soil that has few mineral nutrients. PFAF gives mixed advice on clay. It lists clay as suitable, but says the tree dislikes it. Its growing notes warn against chalk soils. Once established, the tree can cope with dry soil and drought. The account says it also tolerates moist and wet ground.

Reports of how much cold it can bear vary widely. One gives long-term tolerance to 21°F [−6°C]. It also gives brief exposure to 16°F [−9°C]. Another gives survival limits of −4 to 5°F [−20 to −15°C]. PFAF lists USDA zones 7–10. Protect young trees through their first winter after planting. The tree can cope with coastal exposure. But salt in the air may scorch its leaves. This makes it less useful where clean leaves matter most.

The tree can form a woodland canopy or a shelterbelt. PFAF also lists it for bog gardens and values its timber. It reports no known food or medicinal uses for this species. Its warning covers eucalyptus oils as a group. It does not show that this species itself is toxic. The stated way to grow new trees is from seed. Sow seed on the surface under glass in late winter or early spring. Move young seedlings into pots of their own. Plant them out in early summer, with cold protection that first winter.