Plant, care & cut paulownia

Is it worth buying a kiri tree (paulownia) for your own garden and how is it cared for? We clarify these and other questions in this article.

The kiri tree (Paulownia tomentosa), also called paulownia, is a feast for the eyes in every garden. He loves warm climates and drought does not harm him. We explain how to plant, care for and prune the paulownia tree with the purple-blue flowers.

Paulownia: flowering time, origin and characteristics

The blue-purple flowers of the paulownia are a real feast for the eyes for every garden lover. The Paulownia tree, also known as the bluebell tree, kiri tree or imperial tree, is a deciduous wood that is native to China and Taiwan. The plants are part of the bluebell family (Paulowniaceae) and have strikingly thick, stiff, gray-felted shoots. When the plants bloom between April and May, the entire crown is covered with around 20 cm long panicles of flowers. These often consist of up to 30 individual flowers that are very large with a length of 3 to 12 cm. Only after flowering do the huge, up to 40 cm large, light green leaves appear, which provide plenty of shade in summer.

The plants come from warm regions and are therefore well adapted to hot urban climates. You can also cope with longer periods of heat and drought. In Germany, they get along very well in wine-growing areas, but in winter-cold regions, on the other hand, the flower buds can freeze to death and the flowers do not appear. Planted as a single tree, a paulownia can grow up to 15 m. Because of the rapid growth in the youth phase, paulownia are also known as a "climatic tree" because they produce a lot of CO in a short time₂ from the atmosphere and are better adapted to climate change than most native woody species.

The most famous paulownia species and varieties

There are several Paulownia species on the market, which differ mainly in terms of their sensitivity to frost. The most well-known are:

• Bluebell tree wild species (Paulownia tomentosa): Adult trees can also tolerate low temperatures, but young plants in particular should be well protected from frost. The plants grow quickly in youth and often look very picturesque in old age.
• Bluebell Tree Hybrid (Paulownia tomentosa ‘NordMax21®’): This hybrid cross was specially bred for the European climate and can withstand temperatures of up to
  - 22 ° C. What is striking about this variety is its upright and particularly rapid growth.

In addition to these two species, there are other Paulownia species, which, however, are not suitable for cultivation in the home garden. They are mainly used for the production of high quality wood.

Plant paulownia in the garden

Paulownias are sold in a wide variety of forms. Starting with cuttings over bare-rooted one to two year old trees to perennial plants As a high-quality bale product or in a pot, there is the right plant for every need and gel bag available.

Location: A sunny location with well drained soil is ideal for the emperor tree. Care should be taken that the soil is not too moist and rich in nutrients, as otherwise the wood grows too "masty" and susceptible to frost. The pH range of the soil should be in a slightly acidic to slightly alkaline environment (6.5 - 7.5). If the soil is too acidic, the pH can be reduced by adding Garden lime be lowered. Sand should be worked into very heavy, clayey soils to avoid waterlogging and long periods of damp. On sandy soils, it is advisable to work in slightly rotted compost or potting soil. Our Plantura organic universal soil With a pH value between 6.1 - 6.9, it is ideal for planting paulownias and many other trees and shrubs. The organic soil is completely peat-free - that reduces the CO₂-Balance compared to conventional soils by up to 60%.

How to plant a kiri tree:

• Time: Small plants only after mid-May, perennial bales from March.
• Plant spacing: 4 m from other trees, so that the picturesque growth can develop.
• Planting hole: 1.5 times the size of the root ball.
• If necessary, mix soil in the planting hole with sand or mature compost.
• Procedure: Put the bluebell tree in the hole; the root neck should be just above ground level; press firmly; model a watering rim with excess soil and water it extensively.

Growing paulownia in a bucket is only recommended in the first few years. The plants are very vigorous and the roots grow very deep, so permanent cultivation in pots is not suitable.

tip: Paulownia are often bitten by game such as rabbits or deer. In areas with a high incidence of these animals, it makes sense to install a bite guard. The non-toxic leaves can also be used as animal feed for farm animals.

Paulownia care: this is important to note

The bluebell tree is very easy to care for. You will find out the most important maintenance measures and their timing below.

Water and fertilize

An adequate water supply should be ensured in the phase shortly after planting. Once the paulownia tree has grown, it can cope well with drought. As a rule, paulownia do not have to be fertilized. If the soil is extremely poor in nutrients, fertilization should be carried out before June. If the fertilization is too high, especially with nitrogen, the branches will otherwise be more susceptible to frost damage in winter.

Cut paulownia

Paulownia trees naturally form a main trunk that, depending on the species, grows more or less straight. A cut is not absolutely necessary. If frost damage can be seen, the dead shoots can be removed generously. "Latching" creates a kind of avenue tree with a long trunk. To do this, the young side shoots are regularly removed until the desired crown height is reached. Alternatively, you can dispense with pruning in order to obtain a more deeply branched, pyramidal tree. In order not to remove any flower buds, it is advisable to plan the pruning after flowering.

Paulownia propagate

The kiri tree can be propagated using root cuttings, seeds or cuttings. Cuttings are particularly suitable because the trees grow faster and better. For the propagation of paulownia, 20 to 30 cm long cuttings of the newest shoots are cut off. These are cut diagonally at the base and then put into the potting soil so that only the top two shoot buds look out of the substrate. A loose, nutrient-poor substrate, ideally a soil for cuttings, is perfect for achieving good rooting of the cuttings. Our Plantura organic herb & seed compost is ideal for this because it is loosened up with perlites and has the right nutrient content. After the cuttings are in the ground, they should be watered vigorously. It is best to move the young plants to a frost-free place over the winter. However, living rooms are not suitable for this because of the warmth and dryness of the air.

Are paulownias hardy?

Most paulownia species are hardy when fully grown. In protected locations and in wine-growing regions, hardly any frost damage is to be expected, even with younger plants. In winter cold regions, however, plants in pots in particular should be overwintered in a frost-free, but still cold place.

Are paulownias poisonous?

The fruits of paulownia are reminiscent of hazelnuts, but are not suitable for consumption. They are classified as slightly toxic. For small children and pets they are usually not particularly attractive, so that there is usually no danger to be feared. The paulownia leaves are non-toxic. In some Asian countries they are even prepared as a meal.

In addition to the bluebell tree, magnolias are also famous for their lush blossoms. Like you the white to pink blooming Magnolias To care for, cut and multiply, you will find out in this article.