Paulownia is a deciduous tree or very rapid growth originating in China and Japan; adult specimens can reach 15-20 meters in height. It has gray, smooth bark; the wood is light, very light but strong. The foliage is broad, roundish, very branched. The leaves are very large, heart-shaped, dark green. In spring it produces numerous trumpet-shaped flowers, of lilac color, large 4-6 cm, which appear before the leaves; after flowering it produces clusters of large woody pods, which contain many small seeds. In a few years it reaches 5-6 m in height; it must be pruned vigorously after flowering for a more harmonious growth and a more compact development of the dense crown. These plants should be placed in places where they can have adequate space to develop; paulownias are grown in many places, including Italy, to take advantage of the wood.
The Paulownia tomentosa is a tree native to China, belonging to the family of the Scrophulariaceae. The genus P. includes 17 species of trees, all endemic to South and East Asia, in particular to temperate-warm or even tropical climates. Some species are characterized by a very fast growth (even 5 meters in a year) and can thus even reach 15 meters in just three years after planting. Once it reaches that dimension, growth stops definitively.
Despite the rapid initial growth, they also turn out to be rather long-lived: in suitable conditions they manage to overcome the century of life.
These plants develop without problems in any soil, even in places that have proved unfavorable to other crops. This tree adapts to all soils, as long as they are well drained. To get the best results you need to guarantee a rather rich and fresh soil, especially during the first years of life and in summer. However, water stagnation must be avoided because it could be the cause of diseases of the hypogeum in the moment of maximum growth.Multiplication
In spring you can sow the big dark seeds, as soon as the walnuts dry releasing them; the seedlings can be placed immediately at home. In spring it is also possible to practice root or branch cuttings.
New specimens can be obtained by seed or cutting
Sowing takes place in autumn, then leaving the box outside so that the cold and humidity make the casing softer, favoring the release of the first radicle in the spring.
Individuals obtained in this manner need at least 6 years of growth before they can flourish.
Root cutting should be done in November. Portions of root of at least 6 cm in length must be taken, ensuring that they are large and healthy. They should be placed in a mixture of sand and peat and kept at a temperature of 18-20 ° C in the dark.
In February, then, they will be shifted to light at about 16 ° until we see the appearance of the leaves. In April they will be placed in larger containers and in an area well sheltered from the winds. In autumn they can be permanently planted.
Pests and diseases
These large trees are rarely attacked by pests or diseases. Often some branches of the plant tend to dry irreparably; it is advisable to remove the dry parts at the end of flowering or in autumn.
In warm and humid areas it may happen that the leaves are affected by powdery mildew. If it occurs with a certain regularity it is good to prevent it by spraying sulfur-based or specific products.
Another rather frequent problem is the armillaria. Unfortunately, there are no specific treatments: you can only do prevention by avoiding excessive irrigation and providing a soil with excellent drainage.
The young plants must also be protected from wilting. It is good to prevent it by distributing a specific fungicide several times.
History and classification
Of the 17 species that make up the genus Paulonia tomentosa is absolutely the most widespread in Europe. It is a pioneer species and needs a lot of light to grow.
The name was given to him by von Siebol in the mid-1800s to honor the daughter of Tsar Paul I, Anna Paulowna.
It was introduced on our continent in 1834 from China, where it was held in high regard.
It is tradition, in fact, to plant one in the garden at the time of the birth of a daughter. The proceeds from the sale of the wood will then be his dowry.
It is also the symbol of the government of Japan and frequently appears on the coins and notes of this country.
It is widely used mainly in the southern areas of our continent, both as a tree, in its natural form, and as a bush of about 3 meters in height (obtained by repeated pruning at ground level).
The cultivation of Paulonia is not difficult. It is in fact a tree that can adapt to different terrain and climate situations.
La Paulonia is not particularly demanding in terms of climate. The areas from which it comes are temperate and with quite intense rainfall during the spring.
The varieties widespread in our country are able to withstand even -25 ° C very well. To preserve the spring bloom it is important, however, that it is placed in an area well sheltered from the cold wind (which could cause the buds produced in autumn to dry). The ideal is to make it grow close to a wall to the south, capable of accumulating heat during the day to return it in the night.
It can be grown safely in a city garden (or used in parks) because it does not fear pollution.
The best time for planting goes from autumn to early spring, but avoid working with frozen or extremely wet soil.
The bare root plants should preferably be inserted in the middle of winter, taking care not to leave the hypogeum apparatus dehydrated.
If we have to wait a few days we can put them in a bin with damp sand. Before proceeding, it is always a good idea to perform a slight tearing: mix water, soil and a few handfuls of very mature manure in a bucket. We insert the roots inside and leave them for a few hours.
We dig a large and deep hole at least 80 cm and soften the walls using a pitchfork (this will help the penetration of the roots.
We insert in depth a tutor high and of diameter at least equal to the trunk (above all if we want to make to grow the sample to sapling)
Place on the bottom of the gravel to help drain the water, then a few handfuls of manure and finally our specimen of Paulonia. We cover with the soil up to the collar and compress well. We water abundantly every ten days throughout the first year.
The Paulonia does not like drastic pruning and generally does not require interventions, especially if left to grow as a tree.
It is good, in any case, to try to avoid cutting large branches because they will struggle to heal, favoring the penetration of pathogenic fungi. It is advisable to intervene only on the lower branches with a maximum diameter of 5 cm.
The cutting at ground level, to favor the growth of more trunks, is instead well tolerated. Performing this operation often, even every year, you get a bush about 3 meters high, very elegant because it is characterized by leaves that can reach up to 60 cm in width. Unfortunately, the flowering is heavily damaged, which will almost certainly never be seen.
Characteristics and uses of paulownia wood
Its wood in the East is considered very precious. It is in fact very light and not very dense, however it is very solid and very little deformation, besides being very resistant to xylophagous insects.
It dries very quickly in the air (it takes about 30 days) and therefore it is not necessary to wait long before being able to work.
It is an excellent insulator and resistant to fire (it does not ignite up to 400 ° C).
In Southeast Asia it is used for the manufacture of footwear, cases and baskets. It is also widely used for the production of fine furniture, musical instruments and boiserie.
Its rapid growth has attracted the attention of industries interested in biomass. It is in fact possible to quickly produce coal and pellets and then make them into a very valuable energy source.
Height and leaves
Deciduous tree with rounded top.
Height from 12 to 20 meters.
Very large leaves at heart.
Erect bunches of about 25 cm, fragrant lilac flowers, in May.
From the Far East.
Isolated ornamental tree
Large bush (with annual pruning)
Tree about 12 meters high.
The leaves are oval, dark green, with ribs in evidence. The back is velvety and lighter
Large clusters of fragrant mauve and cream flowers, with purple dots, of about 8 cm in length
Isolated ornamental tree