The American tulip tree (Liriodendron tulipifera) is definitely not a tree for small gardens: the deciduous tree is one of the largest deciduous trees on the North American continent, is both fast and strong-growing and reaches heights of up to 40 meters when old. However, its popularity as an ornamental and park tree is quickly explained, because both the distinctively shaped, green foliage and the yellow-orange, tulip-like flowers attract astonished glances.
What is the American Tulip Tree?
The American tulip tree (Liriodendron tulipifera) is a large, deciduous deciduous tree suitable for large gardens and parks. It is characterized by green, distinctively shaped foliage and yellow-orange, tulip-like flowers and can reach heights of up to 40 meters.
Origin and distribution
You should never confuse the tulip tree with the sometimes similarly named tulip magnolia (Magnolia soulangeana). Although both species belong to the magnolia family (Magnoliaceae) and are therefore closely related to each other, they are not visually similar.
The tulip tree (bot. Liriodendron tulipifera) is native to eastern North America, where it is widespread between the Great Lakes on the border with Canada across the Appalachians to northern Florida. Here, the largest deciduous tree in North America thrives primarily on moist to occasionally flooded soils in floodplains and valleys.
In addition to the American subspecies, there is another representative of the tulip trees (Liriodendron) in China and Vietnam: the Chinese tulip tree (Liriodendron chinense). Incidentally, tulip trees as well as the closely related magnolia trees can be traced back to a period of at least 100 million years, with both species also thriving on other parts of the world - such as Europe - in earlier geological eras.
The tulip tree came to Europe from North America quite early on: the first specimens were planted in German and other Central European parks as early as the 17th century, where some of them can still be admired today.
Usage
Since the wild species of the tulip tree reaches enormous heights, it should only be planted in large gardens or parks. Here it is particularly suitable for a solitary position, but in parks it also looks interesting and impressive as a group or avenue planting. There are now some significantly smaller cultivars available for home gardens, such as the two varieties 'Fastigiatum' (15 to 18 meters high) and 'Aureomarginata' (12 to 15 meters high). Since these variants have also been refined, they bloom a few years earlier than the wild form - which often only develops their fascinating flowers after the age of 20.
In the USA and Canada, the tulip tree is one of the most important commercial trees. Its light, finely grained wood - which is not without reason also called "whitewood" - is used in furniture production and is used to make doors and window frames, processed into veneers and cladding, but also into toys, musical instruments and coffins. Furthermore, the tulip tree is a valuable raw material in pulp and paper production.
In the garden, the flowering tulip tree serves as a valuable, extremely nectar-rich pasture for bees.
Appearance and growth
At 41 meters high, one of the largest (and at around 450 years old probably the oldest) tulip tree in America is located directly in New York City in the borough of Queens. It is nicknamed the “Queen's Giant”, although there are several other impressive representatives of its genus around the world. One of them is located in the botanical garden of the city of Marburg and is also almost 40 meters high.
Tulip trees grow very quickly at around 30 to 70 centimeters per year, with the pyramid-like crown also increasing in circumference by around 20 centimeters every year. Although this remains quite narrow, it can still be between 15 and 20 meters wide for specimens that are 25 to 35 meters high. The main branches have a steep upward growth. The trunk grows very straight upwards, appears rather slender with a maximum diameter of 150 centimeters and thickens significantly near the ground, which gives the species, which often grows in flood areas, greater stability. Also characteristic is the longitudinally cracked, light gray bark.
leaves
The tulip tree is a deciduous, deciduous tree whose fresh green, alternately arranged leaves turn a bright golden yellow in autumn. The shape of the leaves is distinctive, making tulip trees easy to identify for those in the know: they are divided into four pointed, protruding side lobes. The leaves are also quite large: the actual leaf is up to 15 centimeters long and up to 20 centimeters wide, with the shape being almost rectangular. There is also a petiole about ten centimeters long.
Bloom and flowering time
Depending on the location and weather, tulip trees open their unique flowers between April and May or May and June. The bisexual yellow-orange flowers are reminiscent of tulip flowers in shape; they are initially cup-shaped and later bell-shaped. Thick and fleshy stamens up to five centimeters long protrude from the center of the flower. The flowers of the tulip tree are very rich in nectar and are therefore often visited by bees, bumblebees and other insects.
Unless it is a tulip tree that has been propagated through grafting, you will have to wait a long time for the first flowering: specimens grown from seeds in particular wait at least 15 to 20 years before the first flowers appear.
Fruits
After pollination, the tulip tree develops spindle-like fruits up to seven centimeters long, which are vaguely reminiscent of conifer cones. They are winged and contain about one or two seeds.
Toxicity
All parts of the tulip tree are considered mildly poisonous to both humans and animals. Therefore, both leaves and flowers are not suitable for consumption. Bark and wood, in which the alkaloid glaucin can be found, have a particularly high proportion of toxins. The plant sap, in turn, can cause allergic reactions upon contact, for example through a pruning.
Which location is suitable?
The tulip tree feels most comfortable in a location that is in full sun and protected from the wind. This is particularly important because older specimens in particular have a tendency to break in the wind. The tree also grows in partial shade, but there it grows much more slowly. In addition, the tulip tree does not grow as big in a darker place in the garden.read more
Floor
The optimal substrate for the tulip tree is:
- nutrient-rich and humus
- loose and permeable
- as loamy as possible
- fresh to moist
- acidic to slightly alkaline
In principle, the species also thrives on sandy, dry soils, but in this case it grows much more slowly. However, the floor should definitely be lime-free.
pot culture
Long-term pot culture is not recommended due to the rapid growth and expected size. The species is also not suitable as a bonsai.
Planting a tulip tree correctly
Plant the tulip tree in its intended location as follows:
- Place the tree in a bucket of water so that the roots can soak up.
- Dig a planting hole that is about twice as large and as wide as the root system.
- Slightly loosen the soil on the side walls and at the bottom of the hole.
- Muddy the planting hole well.
- Mix the excavated material with compost and horn shavings if it is too lean/sandy.
- Plant the tree, but not too deep.
- Fill in the soil, tamp it down carefully.
- Water the tree.
- Apply a layer of bark mulch or leaf compost.
In the following weeks you should water the newly transplanted tree more.
What is the best time to plant?
Basically, you can plant the tulip tree in the garden at any time between October and March, as long as the weather is mild and the soil is frost-free. However, since the species has very sensitive roots that can be damaged by planting in autumn or winter, spring is recommended as the ideal planting time - as late as possible and in any case after the Ice Saints.
The correct planting distance
Planting in a single position is optimal. You should maintain a minimum distance of five meters (better more) from other trees.
Underplants
As a heart-rooted plant, you can safely grow the tulip tree with ground cover plants and small ornamental shrubs.- Plant under perennials if they can withstand strong root pressure and naturally require little water and nutrients. The advantage of underplanting is that it practically acts as a water reservoir and prevents the soil from drying out. With age, Liriodendron tulipifera develops a hemispherical root foundation that raises itself and the tree above the ground, thus ensuring greater stability. Of course, underplanting is no longer possible at this point, but it will take several decades or even centuries to get there.
For example, spring commonweed (Omphalodes verna), saint's-wort (Santolina chamaecyparissus), Japanese forest grass (Hakonechloa macra), great cranesbill (Geranium magnificum), yellow loosestrife (Lysimachia punctata) or lady's mantle (Alchemilla mollis) are well suited for underplanting. Since tulip trees have a rather slender habit and form a narrow crown, the space under the tree is often very bright.
Watering the tulip tree
Freshly planted tulip trees should be watered regularly so that they grow more easily. But even with older specimens, timely watering is important if the drought persists, as the trees quickly shed their leaves when there is a lack of water. However, the tulip tree can usually cope with a short-term lack of water. By the way, the magnificent autumn colors only develop when there is sufficient water supply, which is why you should still use a watering can if necessary, even in late summer. Although the tulip tree needs a lot of water, like most plants it cannot tolerate waterlogging. Permanently wet floors should therefore be avoided if possible.
Fertilize the tulip tree properly
In spring and again in early summer you should provide the tulip tree with plenty of ripe compost and a generous handful of horn shavings. The species also thrives on fertilization with rhododendron fertilizer, which acidifies the soil and kills two birds with one stone: the heavily consuming tulip tree receives the nutrients it needs, while at the same time ensuring an acidic, feel-good environment. Fertilization is generally only carried out between April and July, after which the addition of nutrients must be stopped. The reason for this is that the new shoots have to mature in time before winter and no more are stimulated to grow - these remain too soft and would freeze away in frosty temperatures.read more
Cut the tulip tree correctly
Like magnolias, the tulip tree does not tolerate regular pruning, which is why it is better not to attack it with scissors. In addition, any educational or corrective cuts are not necessary; the species develops an attractive crown structure on its own. Only young trees can still have their growth corrected by pruning, but older trees can no longer be corrected. It also makes sense to remove dead or diseased material, which you should do in early spring if possible.read more
Propagate tulip tree
Tulip trees are typically propagated by seeds or, in the case of cultivated forms, by grafting to the wild form. You can also cut cuttings in spring and use them to grow new trees. This is how cutting propagation works:
- Cut head cuttings about ten to 15 centimeters in size in April or May.
- If necessary, remove all but two leaves.
- Cut large leaves in half.
- Slightly bevel the cutting surface and dip it in rooting powder.
- Now put the cuttings in a small pot with growing substrate.
- Water well with lime-free water.
- Cover the pot with a cut PET bottle or foil.
- Place bright and warm at 20 to 26 °C, water and ventilate regularly.
Be patient with your young cuttings: They usually take a long time to develop their own roots. As long as the cutting looks he althy and the soil doesn't get moldy, everything is fine and you don't need to throw in the towel just yet.read more
How do I transplant correctly?
Tulip trees should, if possible, not be moved if they have been in their location for several years and are well established there. The trees tolerate transplanting very poorly because this inevitably damages their extensive and sensitive root network. In any case, large specimens can only be removed with heavy equipment, which involves considerable effort and high costs.
On the other hand, you can transplant relatively easily young tulip trees that have been in their place for a maximum of three or four years and have not yet grown too tall. But here too, this measure needs to be well prepared by digging a spade-deep trench around the tree the previous autumn and filling it with compost. This means that the roots develop more compactly until the following spring, so that the loss is not too drastic. Repot the tree in late spring and be sure to cut it back so that the balance between above and below ground plant mass is maintained.read more
Diseases and pests
Diseases and pests rarely occur in the tulip tree - as in all magnolia plants. The only problem that can become problematic is keeping it too wet, which after a while becomes apparent in the form of rot. To prevent this, make sure you have a species-appropriate location, a loose and well-drained subsoil in which you can install drainage if necessary, and sufficient planting distance.
Sometimes the tulip tree develops brown leaf spots, which can have various causes. They often indicate a lack of water, but can also be due to s alty soil - for example as a result of over-fertilization. A rare but not impossible cause is leaf spot disease, which can usually be easily controlled with a copper sulfate solution.
Wintering
Since the tulip tree is also sufficiently winter and frost hardy, special winterization measures are unnecessary. Only young trees can be provided with light protection if it gets very cold.
Tip
Since the roots of the tulip tree run close to the surface, you should avoid both deep-rooted underplanting and mechanical processing of the tree disc. This could cause irreparable damage to the roots.
Species and varieties
The genus of tulip trees (Liriodendron) only includes two species, both of which can be cultivated as ornamental trees in the home garden. While the American tulip tree in its original form (Liriodendron tulipifera) is only suitable for very large gardens or parks due to its size, the Chinese tulip tree remains smaller with a maximum height of up to 17 to 20 meters in the Central European climate. Although the Asian version is also hardy here, branches and twigs can freeze back in severe frost.
There are also two cultivated varieties of the American tulip tree that are significantly smaller than the wild form:
- Columnar tulip tree 'Fastigiatum': growth height up to approx. 15 meters, very narrow growth
- 'Aureomarginata': fresh green leaves with yellow-green edges, height around 12 to 15 meters
