The Latin species name of the American sweetgum tree, Liquidambar styraciflua, translates as "liquid amber". In fact, this very apt name not only refers to the fact that the aromatic resin of the genus is used for the production of chewing gum (which is why the deciduous tree is also known as "sweetgum" or "redgum" in its native country), but that it turns a bright red-orange in autumn Foliage glows golden in the sun. Because of its decorative effect, the sweetgum is enjoying growing popularity as a medium-sized house and park tree.

The sweetgum tree is so popular mainly because of its beautiful autumn colors

Table of Contents

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  1. origin and distribution
  2. use
  3. appearance and growth
  4. leaves
  5. flowering and flowering time
  6. fruit
  7. toxicity
  8. Which location is suitable?
  9. floor
  10. pot culture
  11. Plant sweetgum properly
  12. What is the best planting time?
  13. The right planting distance
  14. subplants
  15. Water sweetgum
  16. Fertilize sweetgum properly
  17. Properly cut sweetgum
  18. propagate sweetgum
  19. How do I plant correctly?
  20. diseases and pests
  21. hibernate
  22. species and varieties

    23. origin and distribution

    The American sweetgum tree has its home in North and Central America, where it is at home between the state of New York and the Central American state of Nicaragua, primarily in river valleys and on mountain slopes - provided the subsoil there is nutrient-rich, deep and rather fresh to moist.

    The species belongs to the genus of sweetgum trees (Liquidambar), which was formerly part of the witch hazel family (Hamamelidaceae). However, botanists are now of the opinion that the group forms its own, very small plant family Altingiaceae with only about 15 species. Sweetgum trees are therefore not only native to North America, some species also thrive in the Mediterranean region (oriental sweetgum, Liquidambar orientalis) and in East and Southeast Asia (e.g. the Formosa sweetgum, Liquidambar formosana).

    In Europe, however, the American sweetgum is mainly cultivated as an ornamental and park tree. The species arrived in the Old World as early as 1681, with many varieties of different growth and height now available.

    use

    While the American sweetgum tree is mainly cultivated as an ornamental tree in private gardens and public parks, it is a valuable utility tree in its homeland. Not only is the sweet-smelling Storax, as the resin of the species is also known, an important raw material for the production of chewing gum and is used in natural medicine, but the hard wood of the sweetgum tree, which is very similar in grain and color to walnut wood, is also in high demand in furniture manufacture.

    Furthermore, the aromatic sweetgum wood and its resin are also used as raw materials for the production of perfumes, soaps and other cosmetics. Although the resin of the tree is referred to as "Storax", the sweetgum tree is by no means related to the actual storax tree (Styrax americanus) - it only replaced it in the 18th century in the extraction of resin.

    appearance and growth

    In their homeland, wild specimens of the sweetgum tree reach heights of up to 45 meters. This makes the species one of the highest-growing deciduous trees, but in Central Europe it usually does not reach more than about 20 meters, even in regions with a mild climate. In addition to the tall species, there are some varieties that remain much smaller and reach heights of between around four and a maximum of ten meters and are therefore also suitable as house trees for private gardens.

    When young, the sweetgum tree has a conical, rather narrow habit, but can grow wide with age. The bark, which is initially red-brown, later turns grey-brown and develops broad furrows as well as the cork ridges characteristic of the species.

    leaves

    The sweetgum tree has another name, which it owes to its maple-like leaves: it is called the starfish tree because the five- to seven-lobed, hand-shaped leaves are strongly reminiscent of sea creatures. Laypeople often confuse the sweetgum tree with the native maple due to the shape of its foliage.

    During the summer months, the leaves, which are arranged alternately and can be up to 15 centimeters long, are shiny green, but often take on their beautiful autumn colors from the end of September. Nature seems to dig deep into the color pot of the sweetgum tree, because the color palette ranges from yellow-orange to orange-red and carmine red to violet tones. This broad coloring can often even be observed on one and the same tree.

    This makes the American sweetgum one of the garden trees with the most beautiful autumn foliage, which is also the main reason for its popularity as a house and ornamental tree. Incidentally, the leaves also give off the characteristic aromatic scent when you rub them gently between your fingers.
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    flowering and flowering time

    The rather inconspicuous blossom of the sweetgum tree appears in the merry month of May. The species is monoecious, developing both female and male flowers on the same plant. Male flowers resemble erect, greenish spikes and are about five to seven centimeters long. The female inflorescences, on the other hand, sit on chestnut-like, hanging balls. Pollination is via insects.

    fruit

    At first glance, the globular fruits of the sweetgum tree, which are covered with long thorns, resemble the fruit pods of the sweet chestnut. However, they are significantly smaller with a diameter of two to three centimeters, and they are also made up of numerous woody capsules. Only from the age of about 20 years sweetgum trees produce fruit. These stick to the tree for a long time and often only fall to the ground in spring.

    On the ground, the brown fruit bursts open, allowing the small seeds to fall straight to the ground. However, the largest part is not germinable and therefore cannot be used for propagation. You can recognize the sterile seeds by the fact that they are remarkably small and rather angular in shape. Only a few seeds are fertile and therefore germinable. They are significantly larger, elliptical in shape, and have membranous wings that the wind uses to carry them to potential new locations.
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    toxicity

    Although the resin of the sweetgum tree is still an important raw material for the production of natural medicines and chewing gum, it is only harmless after it has been industrially processed. Otherwise, all parts of the plant are considered to be irritating to toxic for the skin and mucous membranes of both humans and animals, with symptoms of poisoning occurring primarily in children and small pets.

    Which location is suitable?

    As in its natural locations, a sweetgum tree cultivated in the garden also needs a location in full sun and as warm as possible. It is best to plant the tree in a place protected from wind and rain in front of a light-colored house wall or wall, which is also optimally oriented to the south. Here the tree gets enough sun and protection, which it needs especially in the first few years - the species only develops its frost hardiness with increasing age. In addition, a windbreak is important because the sweetgum tree loses its protective foliage quite early in the year.

    On the other hand, a place even in a partially shaded to lightly shaded location is usually too dark. The species develops its colorful autumn leaves only in very sunny and warm locations.
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    floor

    The optimal soil for the American sweetgum is deep, loose and well drained, moderately rich in nutrients to humus and fresh. At best, put it in loamy soil, because the species does not tolerate poor sandy soils or calcareous subsoil very well. While the sweetgum tree grows very slowly on sand, it quickly develops unhealthy yellow leaves on calcareous soil. Waterlogging, in turn, leads to rot and thus to the death of the tree.

    pot culture

    Since the sweetgum tree is very sensitive to cold, wind and other weather influences in the first few years, you should first cultivate it in a large bucket and gradually get used to the climatic conditions. In the long run, however, the tall species cannot be kept in a planter without severely restricting its growth. Sweetgum trees grown as bonsai, for example, require a lot of attention and care.

    Plant sweetgum properly

    Plant the sweetgum tree as follows:

    • Dig a planting hole.
    • This should be twice as wide and deep as the root ball.
    • Loosen the soil on the sides and bottom of the hole.
    • Mix the excavation with compost and horn shavings (32.93€) / horn meal.
    • If the soil is heavy, install drainage, for example through pebbles.
    • Plant the tree so deep that the grafting point is covered with soil.
    • Plant a support stake.
    • Connect this securely to the trunk, e.g. B. with a bast ribbon.
    • Fill in the planting hole and carefully tread down the soil.
    • Slurry the fresh soil with plenty of water.
    • Mulch the root disc to keep the soil from drying out.

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    What is the best planting time?

    Basically, the sweetgum tree can be planted both in early autumn and in late spring. However, since young specimens in particular are quite sensitive to cold and wind, you should prefer spring.
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    The right planting distance

    Since sweetgum trees can grow up to 20 meters high and eight meters wide, they need a lot of space. Therefore, the species is only suitable for a solitary position in the garden that meets these requirements - especially since transplanting becomes difficult if not impossible in later years. Furthermore, the sweetgum tree is very well tolerated by pruning, but depending on the variety it is also quite fast-growing and therefore difficult to limit in height and width with secateurs.

    subplants

    Sweetgum trees have loose growth and let quite a lot of light through their crown. Therefore, they can be well underplanted with ground cover and other perennials, as long as they do not compete too much. Bulb flowers such as tulips and daffodils that bloom in spring are very well suited, as are monkshood, autumn anemones, bluebells and hostas.

    Water sweetgum

    Of course, specimens cultivated in pots will need regular watering during the growing season as they cannot take care of themselves. Freshly planted and young sweetgum trees can also be watered with a swing from the watering can in dry weather. Older, well-established trees, on the other hand, can do without additional watering.

    Fertilize sweetgum properly

    The same applies to the supply of fertilizer: only young trees benefit from a spring fertilization with compost and horn shavings to speed up their slow growth. In the case of older, well-rooted sweetgum trees, however, an additional nutrient supply is not necessary.
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    Properly cut sweetgum

    Sweetgum trees are very tolerant of pruning and can therefore be kept as a bonsai or as a pot culture for a few years. In contrast to fruit trees, however, regular maintenance or care pruning is basically unnecessary, and such a measure also affects the natural growth habit. It is therefore best to simply let the tree grow and only remove dead, diseased and too dense wood in spring.
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    propagate sweetgum

    As a rule, sweetgum trees are propagated by grafting, but can also be grown from seed. In contrast to grafted specimens, however, seedlings are unpredictable in their properties, and only a few of the mature seeds are actually germinable. Choose only large, elliptically shaped seeds for sowing.

    These need a cold stimulus so that the germ inhibition is broken. Therefore, store the seeds in the vegetable compartment of the refrigerator for about two months or sow them in a covered cold frame in the fall. From spring onwards, the seeds need constant temperatures of 20 °C and above for germination and growth.
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    How do I plant correctly?

    Once planted, sweetgum trees should only be replanted within the first three to a maximum of five years. After that, they usually only tolerate a change of location very badly.

    diseases and pests

    Diseases and pest infestation occur very rarely on the sweetgum tree. On the other hand, typical location and care errors, such as those shown, are more common

    • in too dark locations
    • compacted or otherwise unsuitable soil
    • when it is too dry
    • with insufficient fertilization
    • as well as in case of waterlogging

    appear. Affected trees get yellow to brown leaves that are shed after a while. In addition, they grow very poorly. Since sweetgum trees are very sensitive, they can die off quickly, particularly as a result of too little/too much water.

    hibernate

    Only the American sweetgum is sufficiently hardy in Central Europe, both the oriental and the Asian Formosa sweetgum come from climates with mild winters and are therefore not frost-tolerant. However, the American relative only develops its frost hardiness with increasing age, which is why some experts recommend a bucket culture and gradual hardening, at least for young trees. Later, when the tree has been planted out, it will receive winter protection for the first few winters. To do this, cover the root area with brushwood, mulch (€239.00) or straw and wrap the trunk with garden fleece if the temperature is below zero. Later, however, the tree develops sufficient frost hardiness.

    tips

    The leaves that are thrown off in autumn are best left lying around: they not only serve as natural winter protection, but also provide the tree with valuable nutrients through the rotting process.

    species and varieties

    In this country, only the American sweetgum tree (Liquidambar styraciflua) is hardy, which can withstand temperatures of down to minus 24 °C in sheltered locations. There are now some beautiful varieties of this species that are wonderfully suitable for the home garden:

    • 'Gumball': slow-growing variety with a maximum height of two meters and a spherical crown
    • 'Oktoberglut': very popular variety with bright, colorful autumn colors and a maximum height of three meters
    • 'Variegata': variegated white foliage, maximum height of two meters, perfect for long-term pot keeping
    • 'Worplesdon': slow growth, up to a maximum height of ten meters, fiery red autumn colour
    • 'Silver King': also variegated white foliage, bright red autumn colours, maximum height of five metres
    • 'Slender Silhouette': slim column shape with a maximum width of one meter, wonderful for small gardens

    Other species of sweetgum, such as the Chinese sweetgum (Liquidambar acalycina), the oriental sweetgum (Liquidambar orientalis) or the Taiwanese sweetgum (Liquidambar formosana), on the other hand, are not suitable for planting out in Central European gardens, but can be planted in sufficiently large pots and with much more care Care in conservatories or outside during the summer months.

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Trees