If you think of koalas, you automatically associate eucalyptus trees with them. Did you know that they also thrive here with us?
At first you might think of eucalyptus not as a plant but as an aromatic candy. You are forgiven for this. At the same time, it is reason enough to take a closer look at the eucalyptus trees. These belong to the myrtle family, are also called blue gum trees and are incredibly rich in species. More than 600 different species have already been described. Among them is a real giant with the giant eucalyptus. The deciduous tree with the highest growth height reaches almost 100 meters. For the hobby gardener, this plant is understandably less interesting. But there are also numerous species that feel comfortable in the garden and on the terrace and like to spend the summer there. The eucalyptus also cuts a fine figure as a houseplant. The exotic plant proves to be quite easy to care for and robust. If you follow the tips and advice below, you will be sure to enjoy your blue gum tree for a long time.
The Appearance of Eucalyptus
Because of the extraordinarily large number of species, certain differences in the appearance of the eucalyptus can also be seen visually. As they age, blue gum trees change the appearance of their bark. New layers of bark increase the trunk circumference of the trees every year. In some species, the outer layer then peels off, while in others it remains on the trunk. This gives the trunks a different appearance. There are also differences in the leaves. After budding, the leaves are usually opposite. The adult leaves are usually heart- to ovoid-shaped.
Origin and Distribution
The original home of the eucalyptus tree is in Australia and Tasmania. The natural range of the plant genus is also in eastern Indonesia. In Australia alone, three quarters of all tree species consist of eucalyptus plants. Numerous species of blue gum trees are now also native to the subtropics worldwide.
The eucalyptus was first scientifically described at the end of the 18th century.Century by Charles Louis L'Hérité de Brutelle, a French botanist then based in London. The plant name comes from ancient Greek and alludes to the closed calyx with the word correspondence "beautiful" and "hidden".
Use of Eucalyptus
Eucalyptus leaves are the koala's favorite food. Furthermore, the plant is used for the extraction of essential oils and also used for wood production. Essential oil can be obtained from around 50 types of eucalyptus alone. Eucalyptus oil was used for medicinal purposes as early as 1850. The blood circulation-promoting and anticonvulsant effect of the plant was used. Areas of application of eucalyptus oil are:
- cough
- Hoarseness
- Rheumatism
- Bladder diseases
- Nervous Pain
Caution:
The leaves of the eucalyptus contain toxins. Eucalyptus oil should therefore not be taken in large quantities and is even taboo for people with high blood pressure, liver problems or diseases of the digestive tract.
When does the eucalyptus bloom?
The white flowers of the eucalyptus appear between September and December. The doldigen inflorescences are densely covered with flowers. These are fourfold hermaphrodite flowers. The buds are surrounded by a capsule called the operculum. When the flower opens and the stamens expand, the capsule detaches. The infructescences are often reminiscent of cones.
An overview of different eucalyptus species
❍ Snow Gum:
The snow eucalyptus comes from Australia and grows there in regions up to 1,800 meters. The robust species has a rather low growth height of a maximum of ten meters.
❍ Silver Dollar Eucalyptus:
The Silver Dollar Eucalyptus only grows in Tasmania. The plants grow there as trees or as shrubs. The growth height is between ten and twenty meters.
❍ Jarrah Eucalyptus:
The Jarrah eucalyptus grows in western Australia. The wood is not attacked by termites and is valued in the manufacture of furniture and musical instruments. The trees can get very old. A specimen found in Armadale is estimated to be around 600 years old.
❍ Powderbark Eucalyptus:
On the west coast of Australia is the home of the powder bark gum. The trees are about 15 to 25 meters high. They bloom from December to April and have a strikingly smooth bark with attractive pink-orange hues.
How to plant eucalyptusright on
The original home of the eucalyptus is the tropics and subtropics. Nevertheless, nothing speaks against cultivation in our latitudes. Some species even tolerate light frosts. The eucalyptus gunnii, which is also unaffected by sub-zero temperatures, has proven to be a popular species for cultivation in the home garden. We will tell you here what you need to consider when planting the blue gum trees.
Location:
To be able to do justice to the tropical plants, a bright and warm location is needed. The plants like direct sunlight. This is reflected in a fast and attractive growth and a strong leaf color. Some species also tolerate sub-zero temperatures. Eucalyptus gunnii "Azura" in particular is one of them. The variety tolerates temperatures down to -20 degrees. However, resistance to light frosts applies only to outdoor plants. Potted plants are more sensitive and need winter protection.
The eucalyptus tolerates partial shade to a limited extent. However, this is at the expense of the joy of growth and the pretty leaf colouring. A sheltered location is also required. The tropical plants don't get wind and drafts.
The ideal location in keywords:
- light
- warm
- full sun
- protected
Substrate:
The demands on the substrate are rather low. However, it should be a nutrient-rich soil. It is therefore advisable to enrich the soil with compost when planting and thus ensure organic long-term fertilization of the plants. Since they do not tolerate waterlogging, you should provide drainage made of potsherds or gravel. This is a must, especially for potted plants.
The ideal substrate in keywords:
- fresh
- nutrient rich
- Add compost
- Create drainage
Planting Instructions for Eucalyptus:
The best time to plant eucalyptus is early spring. Choose a mild and frost-free day and proceed as follows when planting:
- Select location.
- Loosen the soil.
- Dig the planting hole.
- Mix the compost under the substrate.
- Create drainage.
- Place plant.
- Fill substrate.
- Press the base lightly.
- Water the plant well.
Keep eucalyptus as a houseplant
Eucalyptus can also be cultivated as a houseplant. Here it makes sense to use eucalyptus gunnii. This quite robust strain growsless fast. This species grows less than 50 centimeters in height each year. Most species more than double in height each year and would therefore need to be cut back regularly to make them suitable as houseplants.
Care for the houseplant:
The plant also needs a bright sunny spot indoors. However, the blue gum tree is tolerant at ambient temperatures. The eucalyptus will grow just as well at room temperature as it will in slightly cooler rooms.
During the growing season, the plant needs sufficient moisture. The soil should not dry out even in winter. Compost is also a suitable substrate for indoor plants.
Cultivate eucalyptus as bonsai
Eucalyptus are particularly vigorous, which makes them not really easy candidates for bonsai training. However, it is worth the effort. The robust and frost-resistant species Eucalyptus gunnii can be cultivated particularly well as a bonsai. Upright forms are the most popular design styles of eucalyptus bonsai.
Care for the bonsai:
In the summer the bonsai can get a place in the sun outside. Hibernation takes place in light and at temperatures around 15 to 18 degrees. Make sure you have enough water. The root ball should always feel moist. You can give bonsai fertilizer in the growth phase, between April and August, at weekly intervals. You have to follow the pruning consistently due to the rapid growth. The bark of the trees is particularly sensitive. Wiring is therefore not advisable. The eucalyptus bonsai needs a larger planter about every three years.
How to properly care for eucalyptus plants
Casting:
In relation to comparable plants, the water requirement of the blue gum tree is rather low. The hard-leaved leaves evaporate relatively little water. Nevertheless, you should water the eucalyptus moderately but regularly. The water requirement increases on hot summer days. The substrate should be allowed to dry between the individual waterings. This makes it easier to assess whether the plant really needs water. Because the plants do not tolerate waterlogging. In winter, the plants also need significantly less water, but should never dry out completely.
Important:
Water preferably with rainwater. The eucalyptus does not tolerate calcareous tap water.
Fertilize:
Mix the potting soil with compost and the young plants are supplied with an effective long-term fertilizer anddo not require additional fertilizer in the first year after planting. Otherwise, it is necessary to administer fertilizer during the growing season. Commercially available liquid fertilizer, for example, is well suited. You should add this to the irrigation water every two weeks. When buying, make sure that the proportion of phosphorus and nitrogen is as low as possible. From August you should no longer fertilize.
Pruning:
What was visibly neglected in the case of the giant eucalyptus, which is up to 100 meters high, is essential for the indoor or container plant. Regular pruning is essential if we don't want the blue gum trees to grow too much. However, this can be done without any problems, because the plants are very well tolerated by pruning. Pruning measures on plants outdoors and in containers are preferably carried out in spring. Larger wounds should be treated with a wound sealant. Do not prune the roots of the plants.
Houseplants can be trimmed all year round. Species that are particularly keen on growing also several times. The scissors don't need to be applied as often to the Eucalyptus gunnii as the plant only grows about 40 centimeters per year.
Repot:
The plants grow quite quickly, which means that they have to be repotted regularly. Depending on the choice of planter, the measure may also be necessary twice a year. Choose sufficiently large planters so that repotting is not necessary several times a year. Roots pushing out of the planter tell you that the plant needs a larger container. When transplanting, you should protect the root area. You must also completely cover the roots with the new substrate.
Hiberation:
Some eucalyptus species are considered conditionally hardy. In our latitudes, however, the winters are usually too cold and harsh for the blue gum tree to do without winter protection. Small trees planted outdoors need winter protection from garden fleece. You should also cover the root area with brushwood or leaves. Only eucalyptus gunnii is considered to be quite robust and can withstand temperatures down to -12 degrees.
Container plants should generally be overwintered indoors. The plants are less robust in the tub and the frost would attack the sensitive root system. The winter quarters should be bright. Therefore, a conservatory is ideal as a place to spend the winter. The temperatures should not fall below eight degrees. Houseplants can also hibernate warmer, but should then be watered as usual.
Pests and diseases amRecognizing and fighting eucalyptus
The eucalyptus proves to be robust against diseases and pests. This is probably due not least to the essential oils, which deter numerous pests. Nevertheless, it can occasionally happen that aphids or spider mites appear on the eucalyptus.
Especially in spring, aphids can be seen on the tips of the shoots. The common spider mite then also appears more frequently. You can clearly recognize the pest infestation by the dark sooty mold or the cobweb-like network. Aphids can usually be eliminated without the use of chemical pest control. If the infestation is detected early, it can already help to remove the pests with a jet of water. If the plant takes an immersion bath in cold water for about a day, aphids will be reliably killed even with heavier infestations, while you will not harm the plant itself. Treatment with soft soap solution or nettle manure (instructions for nettle manure) can also help with aphids and spider mite infestation.
How to propagate eucalyptus?
Propagation by sowing has proven itself for the blue gum tree. The seeds can be obtained directly from existing plants or purchased from specialist retailers. Eucalyptus cultivated as a houseplant usually does not flower and therefore does not form seeds. Proceed as follows when sowing:
Sow the seeds in a moist sand and peat mixture. For germination, the seeds then need constant temperatures of 22 to 24 degrees. In order to ensure this, accommodation in a breeding box is a good idea. The germination time is about 3.5 weeks. When the first leaves appear, you should prick out the young plants and place them in larger containers. Compost is suitable as a substrate. You can now treat the young plants as already described and they will usually quickly grow into strong eucalyptus trees.