Known for its menthol-like scent and as a filler in cut flower arrangements, eucalyptus plants can also make stunning container plants and showy annuals. These tough trees have numerous species available (over 700!), and most are native to Australia. Although these plants can reach over 200 feet tall, they can be used seasonally in many gardens, and even as a houseplant.
Most notably, eucalyptus is grown for its potent essential oils, which are commonly derived from the species E. globulus. These fragrant oils are used in many different ways; medicinally, for their cleansing properties, and to scent perfumes and fragrances. All parts of the eucalyptus plant produce these oils, but they are most commonly derived through steam distillation of the leaves. Because eucalyptus is rich in these compounds that are highly volatile, the plants are of some concern to firefighters because they can very quickly burn. On very hot days, forests of eucalyptus can be seen shrouded in a fog. This is actually caused by oil compounds of the plant becoming vaporized due to the heat.
Related: 16 Top Fragrant Indoor Plants
Eucalyptus Care Must-Knows
Eucalyptus are easy, fast-growing plants, and they like well-drained, consistently moist soils. If you are planting one as a tree, be aware these are water-hungry plants. In a container, use any general purpose potting media, and make sure to plant them in a large pot. Eucalyptus are fast growers, and their roots can quickly fill a small container.
As far as exposure, eucalyptus needs full sun, which helps plants grow sturdy and promotes better branching, brighter silver foliage, and higher oil content. If you are trying eucalyptus as a houseplant, or overwintering one, give it as much sun as possible in the home. Usually a bright southern exposure will work best.
If you are planting eucalyptus in an area where they are hardy, the plant can become invasive. Studies show that eucalyptus trees may exhibit allelopathic affects on some species of plants, which is when a plant releases a toxin into the soil so that competing plants cannot grow. There is still some uncertainty as to the level of allelopathy that eucalyptus trees have, but it's still something to consider when planting.
Eucalyptus trees are also notorious for being messy. As many species age, they shed portions of their bark, littering the ground below. On the plus side, this exfoliating bark can be quite beautiful, especially during the winter. Some species, like E. deglupta, are grown almost primarily for their bark. This species is also known as the rainbow eucalyptus, and as the bark exfoliates, depending on the age, the plants color differently. So whole trunks can be varying shades of yellows, greens, reds, and purples.
Many species of eucalyptus have different-shaped leaves, depending on the maturity of the plant. Leaves may begin as round and coin-shape, then as the plants age, become long, lance-shape leaves. Don't be alarmed if you plant seeds and they aren't quite what you expect. The trees may just need to grow into their proper shape.
More Varieties for Eucalyptus
Eucalyptus globulus 'Compacta' is a fast-growing tree that usually remains less than 30 feet tall, and it's easy to keep trimmed to 10 feet tall. Leaves on immature plants are circular and blue; mature plants produce green sickle-shape leaves 6-10 inches long. Dwarf blue gum bears creamy-white flowers in winter, followed by bluish seed capsules in summer that drop from the tree, making this somewhat of a nuisance tree. Zones 9-11
Eucalyptus citriodora is a large tree that grows 75-100 feet tall and spreads 25-50 feet wide. The tree has two forms of leaves: Juvenile foliage is rough and sandpapery; mature leaves are smooth and glossy. Both types of leaves produce a lemon-scent oil called citronella, which is widely used in perfumes. Lemon scented gum bears small white flowers in winter. Some experts have reclassified this tree as Corymbia citriodora. Zones 9-11
Eucalyptus deglupta gets its name from its multicolor bark. The tree sheds patches of bark irregularly to reveal green inner bark, which darkens with age to blue, purple, maroon, and orange. Also known as Mindanoa or Indonesian gum, it is a large tree, growing up to 200 feet tall and 40 feet wide. Zones 9-11
Eucalyptus ficifolia is one of the showiest of eucalyptus trees. It bears clusters of red, orange, pink, or white flowers above the tree canopy sporadically throughout the year. The tree grows 25-40 feet tall and wide. In recent years, botanists have reclassified it as Corymbia ficifolia, but you'll often find it sold by its traditional name. Zones 9-11
Eucalyptus sideroxylon is called red ironbark because mature trees develop deeply furrowed reddish-brown bark. This tree may grow strongly upright to 80 feet tall, or it may be weeping in form and remain below 20 feet tall. The width ranges from 20-45 feet. Leaves on juvenile plants are bluish white and lancelike in shape. Mature trees produce sickle-shape leaves that turn bronze in winter. Flower color varies from pinkish white to red. Zones 9-11
Eucalyptus cinerea is a small tree that grows up to 30 feet tall and 10-15 feet wide. The silvery leaves are round and gray-green, giving rise to the tree's common name. As the plant ages, leaves become more oval and elongated. It is hardy in Zones 8-11 but may die back to the ground in severe winters. In colder Zones it can be grown as an annual, reaching up to 8 feet tall in a single season. Cut stems are often used in floral arrangements.
Eucalyptus gunnii 'Silver Drop' is most commonly grown as an annual for its fragrant silver-green foliage. As an annual it grows 2-3 feet tall and wide. The species from which it is selected can grow to 40 feet tall and wide where it is hardy. Zones 8-11
Eucalyptus maculata is also sometimes classified as Corymbia maculata. It gets its common name from its irregular bark coloration. The bark sheds in flakes, leaving spots of white, gray, green, and pink. The tree bears white flowers in summer. In cultivation it reaches 60 feet tall and 30 feet wide. Zones 9-11