The large, silky, elegant brush flowers gave the silk tree its name. But even apart from these magnificent structures, the tree that comes from Asia has a few curiosities in its luggage. Read this article to find out why its cultivation is definitely worth it.
What characterizes the silk tree (Albizia julibrissin)?
The silk tree (Albizia julibrissin) is a partially hardy tree native to Asia that impresses with its delicate leaf structure and magnificent, silk-like flowers. It can grow up to 6-8 meters high and prefers sunny, protected locations with humus-rich and permeable soil. Outdoor cultivation is possible in mild areas.
Origin
The silk tree, botanically Albizia julibrissin, is a species from the genus Albizia, which belongs to the mimosa family. It originally comes from large parts of Asia, from the Middle Eastern areas from Iran to what we see as the last Asian corner in Japan. It inhabits temperate habitats and is therefore partially hardy.
Due to its extensive independent distribution, especially in temperate climate zones in the USA, the silk tree is also a neophyte - meaning it has also found new homes outside of its original areas of origin. For example, it has long been widespread as an ornamental plant in the Mediterranean area.
Due to increasingly warmer global temperatures, it will also be able to penetrate more and more northern areas in the long term. Here in Germany it can actually be cultivated without any problems in parts of the country that are not too frosty.
Origin at a glance:
- Silk tree originally comes from Middle to Far Eastern areas
- As a neophyte but also spread in temperate zones of the USA
- Very popular as an ornamental plant in the Mediterranean region
- Easily cultivated in areas with moderate frost risk
Growth
The silk tree grows as a delicate tree, and its habitus is sometimes described as shrub-like. Its delicate, slender trunk is covered in dark gray bark and has branches relatively far down, which form a swinging, sweeping crown with delicate branching. Overall, a silk tree can grow up to 6 or 8 meters high, but only under particularly favorable conditions. It grows 20 to 40 cm per year and usually only lives around 30 years.
Growth characteristics in brief:
- Fine, richly branched shrub-like to tree-like growth
- Splendid, swinging crown
- Moderate maximum height of 6-8 meters
- Maximum age around 30 years
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leaves
Even apart from the spectacular flowers, the silk tree is a feast for the eyes for lovers of delicate structures. Its foliage features elongated, egg-shaped, fine double-pinnate leaves that sway gracefully and gracefully in the wind. The individual leaflets have a sickle-like shape of 7 to 18 millimeters and are in 4 to 15 pairs on the petiole. Their edges are finely toothed and there is clear hair on the midribs. The entire leaf reaches a length of about 7 to 15 centimeters.
The leaves have another curious property: they close at night and enter a kind of sleep mode. At daybreak they open again. This is why the silk tree is also called the “sleeping tree”.
Leaf properties in keywords:
- Doubly pinnate leaves with a very graceful and delicate appearance
- Individual leaves 7-18 mm long, total leaf length 7-15 cm
- Finely toothed edges, midribs hairy
- Close at night - hence the nickname “sleeping tree”
Flowers
The flowers of the silk tree surpass its range of graceful beauty - it is not for nothing that they are also the namesake of its main name. In fact, their very fine, smooth texture gives them a silky appearance.
They are characterized by long, filigree stamens that form a puff-like tassel 2 ½ to 3 centimeters in size. They stand singly, in pairs or threes, on 3 ½ to 7 cm long inflorescence shafts and have a 3 to 6 mm long bract. With their striking play of colors, which transition from a yellow center on the stamens to an intense pink to scarlet pink, the flowers stand out magnificently from the medium green foliage.
When is flowering time?
As with many beautiful things, the duration of the silk flower bloom is limited and therefore all the more precious. The tree only shows the admirable structures between July and August. If you don't want to miss the blooming season, it's better to plan your summer vacation in June or the off-season!read more
Which location is suitable?
The silk tree likes it sunny, warm and protected. In the garden you should plant it in a sunny to semi-shady place that is not too exposed. A south to southwest facing spot on a house wall is ideal, where the delicate plant is not ruffled by strong gusts of wind.
If you cultivate the silk tree in a pot, a parking space on a protected, south-facing balcony (€5.00 on Amazon) is also conceivable.
Location requirements coming soon:
- Warm and sunny
- Protect as much as possible from strong winds
- Not exposed
What soil does the plant need?
The silk tree has a moderate to high nutrient requirement and therefore needs humus-rich soil. If you plant it in the garden, you should enrich the planting hole well with compost and horn shavings. However, good permeability is also necessary - so if possible, add sand to the potting soil, especially if the soil at the planting location is rather heavy. This also prevents excessive watering, which can have a damaging effect on the roots in the event of frost.
If you want to keep the silk tree in a pot, it is also important to provide the soil with a fair amount of organic long-term fertilizer, i.e. compost and/or horn shavings. A portion of sand is not a bad idea here either, but a little expanded clay is even better in the narrower pot planting area for good drainage.
Substrate rules at a glance:
- Silk tree needs relatively nutrient-rich soil
- Add compost and horn shavings when planting
- For good permeability, loosen heavy soils with sand
- For pot cultivation also humus-rich soil, loosened with sand or expanded clay
Planting out
To plant, first select a suitable, sunny and protected location. Provide the planting hole you have dug with a good drainage layer of sand and, if necessary, some gravel. Fill the rest with humus-rich, sandy, loosened soil. The best time to plant is spring after the last frosts.read more
hardy
The silk tree is conditionally hardy - that is, it can only tolerate frost to a certain extent; specifically, limit values of around -15°C are specified. In very cold areas of the country, long-term outdoor cultivation can be critical.
You should especially protect young, newly planted specimens prophylactically against cold damage in winter. The best way to do this is to wrap the delicate trunk with raffia or burlap. Cover the root area with similar material or with pine branches. As the silk tree gets older, it becomes less and less sensitive to frost.
When growing in containers, cold protection is of course even more important, but also easier to do. Either cover the pot with burlap etc. or place the plant in a place to overwinter where there are no double-digit temperatures, such as a cold house.
To remember:
- Silk tree hardy down to around -15°C
- Protect especially young trees in winter by wrapping the trunk and covering the root area
- Wrap specimens kept in the bucket and cover them or place them in a place that is more protected from the cold
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Watering the silk tree
When grown outdoors, you don't actually need to water the silk tree, only in long periods of drought.
When grown in containers, the plant relies more on your watering. Make sure it gets regular water, either from rain or from your watering can.
Fertilize silk tree properly
You do not need to particularly fertilize a planted silk tree. If the planting soil is reasonably humic, it will provide a sufficient nutrient base. If the soil is poor or heavy, it is even more important to improve it with lots of compost and horn shavings when planting and, if necessary, top it up again in the spring.
In pot cultivation, in addition to the organic long-term fertilizer, you can also use a universal liquid fertilizer during the growing season, which you add to the irrigation water about every 2 to 4 weeks. A regular addition of compost or your own nettle manure also works.
Fertilizing at a glance:
- In open field cultivation only organic long-term nutrient supply
- Provide liquid fertilizer in the bucket every 2-4 weeks during the growing season or occasionally add compost or nettle manure
Cut the silk tree correctly
Whether you cut the silk tree depends on whether you want to keep it in the form of a shrub or let it grow into a tree. If you prefer a shrubby, more compact and lower habit, cut the silk tree back every spring. But don't do it too intensively, just remove any long, annoying shoots. The silk tree can also tolerate radical pruning if necessary.
If you want to grow the silk tree into a pretty little tree - which is particularly recommended for airy and atmospheric shading of a seat - only cut out dried branches after the winter to give the plant a vital boost.
To remember:
- Silk tree can be cultivated specifically into a shrub form through regular spring pruning
- When letting it grow into a tree: no or only cleaning pruning
Bonsai
Due to its good pruning tolerance, the silk tree is suitable for bonsaiists. It can easily be grown into an artistically shaped mini tree in a pot. All common methods including wires can be used. However, you have to be careful when wiring - the wood of the silk tree is a bit soft and in combination with the fairly fast growth, wires grow in easily.read more
Propagation
You can propagate the silk tree either by cuttings or by sowing.
Cuttings
With this proven method, you cut top cuttings from the crown in spring, defoliate them in the lower area and put them in a container with potting soil. For rooting, keep the substrate evenly moist, possibly under foil. However, the ambient temperature should be relatively high, around 25°C is ideal.
Seed cultivation
But a silk tree can also be easily propagated from seeds. You can easily get seeds from the elongated fruits that the tree produces after flowering. Remove the seeds from the fruit in autumn and dry and store them in a cool, dark place over the winter. In spring, first soak them in lukewarm water. You can also roughen the seed coats a little beforehand - this will make it easier for the seedling to “hatch”.
The seeds prepared in this way are placed in planting trays with potting soil and only cover them lightly, as they germinate in light. Place the plant bowls in a place that is also around 25°C warm and bright. Keep the substrate evenly moist. A cover with foil or a mini greenhouse for a protected microclimate is recommended.
When the trees have reached a size of around 15 to 20 centimeters, you can transplant them, but not outdoors yet. To do this, you should become significantly taller.read more
cultivation
See section “Propagation – seed cultivation”read more
Is silk tree poisonous?
Unfortunately, the silk tree is not a completely safe candidate for gardens in households with small children and pets. Its fruiting bodies and seeds contain toxins that can be dangerous to curious garden visitors in summer and autumn.read more
Tip
In order to promote straight growth in a sapling culture, it is recommended to tie the tender trunk to a support post after planting. However, do not use a coarse cord, but rather a soft, wide jute ribbon to prevent ingrowth.
Varieties
Albizia julibrissin Ombrella
The name of the variety A. j. Ombrella is somewhat misleading in this common spelling, as it suggests a particularly shadow-affinous or shadow-casting property. The spelling A. j. Umbrella provides information: The special feature of this variety is the umbrella-like growth that characterizes the crown. This in turn makes it suitable as a romantic roof for a shady spot, despite the name not being motivated by it. Their long leaflets are very decorative with their numerous structure.
In July and August the pink, large clustered flowers appear, which are lightly scented.
The A. j. Ombrella can grow up to 8 m high and requires a sunny location. It is a little less winter-hardy than its counterparts and should be well protected in severe frost.
Albizia julibrissin Summer Chocolate
What does this variety have to do with chocolate? It's simple: its leaves are colored a reddish dark brown, so it can awaken true chocolate dreams in summer. In terms of size and structure, they have the same feathery appearance as their counterparts.
The A. j. Summer Chocolate also blooms in July and August - with light pink to pink cluster flowers that stand out very attractively against the brown foliage and spread a pleasant scent. With a maximum height of 4-6 meters, the variety is slightly smaller than the A. j. Ombrella.
Albizia julibrissin Ernest Wilson
This variety refreshes with the graceful color contrast of its leaves and flowers. The filigree, feathery foliage is a rich, muted dark green, from which the flowers stand out very attractively with their delicate pink and white base. The A. J. At around 4 to 5 meters high and around 5 to 6 meters wide, Ernest Wilson remains in a more shrub-like habit. It is interesting for those who live in colder areas of the country because of its particularly good winter hardiness.
