Eucalyptus globulus

Eucalyptus globulus or Blue Gum is one of the most imposing species of the genus and one of the most used for its essential oil. In less than 10 years, it can form a beautiful tree only in a mild, coastal climate, as its hardiness is very limited. It has a very decorative, green-blue juvenile foliage, which elongates and turns green in its adult form. Its cream-white flowering is quite insignificant amidst the mass of foliage, but its unique, massive, and often decorative trunk catches the eye from afar. It grows in full sun, in soils that are slightly or non-chalky, slightly moist but well-drained. A remarkable tree that will structure the landscape in gardens large enough to accommodate it. 

The Common Eucalyptus is a tree of the Myrtaceae family, like the Feijoa, the Callistemon, or the Myrtle, with a flowering characteristic of this family. The genus Eucalyptus, native to Australia, includes more than 800 species, among which are the tallest hardwoods in the world (Eucalyptus regnans). The Eucalyptus globulus is one of these giants. Native to southeastern Australia (Victoria state) and Tasmania, where it has been the emblem since 1962, it can reach a height of 70 m (229 ft 8 in)! It grows in full sun, in open forests, up to 1000 m (3280 ft 10 in) altitude. Its common name Blue Gum comes from the bluish colour of the bloom that covers the juvenile leaves. The English also call it the fever tree, as it can dry out marshes, thus preventing mosquitoes from proliferating.

This impressive tree can only tolerate brief frosts of around -7°C (19.4 °F). 35 m (114ft) is probably the maximum height it will reach in southern climates, with a width of about 20 m (65 ft 7 in), far from Australian records, but still very impressive, making it suitable for very large gardens and parks.

This Eucalyptus has two types of foliage. Juvenile foliage, consisting of opposite, sessile (non-petiolate), ovate leaves, 6 to 15 cm (2.4 to 5.9 in) long, and very aesthetic with their bluish, slightly silvery colour, and adult foliage which is narrower and longer (15 to 30 cm (5.9 to 11.8 in)), sickle-shaped and glaucous dark green. The flowering in late spring is insignificant and consists of solitary flowers about 2 cm (0.8 in) in diameter, forming a pompon of cream-white stamens. Appearing at the axils of the leaves, they are nectar-rich but too small to be considered decorative. The trunk is generally ornamental, it exfoliates in large flakes revealing a smooth, light-coloured bark in shades of beige, cinnamon, cream-white, and others. Indeed, there are several subspecies, each presenting slightly different shades... Generally straight and branching high up, the trunk often reaches a significant diameter, making this tree a master subject in the garden. Thanks to its astonishing growth rate (approximately 2 m (6 ft 7 in) per year), it only takes about 10 years to obtain a 20 m (65 ft 7 in) tall giant! It is therefore important to be aware of this when choosing its location (it should be kept away from the foundations of a house, as its water absorption capacity can quickly become problematic). Once well established, it will tolerate brief episodes of drought but will grow better if it can find sufficient water in the soil.

Eucalyptus globulus has the potential to become a monumental subject in a large space, adding an undeniable touch of exoticism. It is mainly used as a standalone plant due to its imposing dimensions and also because it competes strongly for water with other plants nearby. If the size of the garden allows, it can be planted alongside other trees with ornamental foliage, such as the Gleditsia triacanthos Sunburst, a Golden Honey Locust with leaves composed of a superb yellow that will echo the blue-green of the Eucalyptus. At its base, a Cercis canadensis Forest Pansy, a Judas Tree with purple foliage, will complete this contrasting scene.