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What is Paulownia? The tree, the wood and what’s true about it
Few trees attract as much attention, or as many exaggerated claims. Here is what Paulownia is, why it is used, what it is used for, and which of the things said about it hold up.
Short answer: Paulownia is a genus of fast-growing trees native to China and East Asia, known in English as princess tree or empress tree and in Japan as kiri. Its wood is one of the lightest commercial timbers, at around 260–280 kg/m³, and it is stable, easy to work and pale in colour. It has been used for centuries in Japan for chests, sandals and musical instruments, and today for surfboards, guitar bodies and lightweight panels. One species is invasive in parts of the US and is being watched in Europe; sterile hybrids are grown in plantations.
The tree
Paulownia is a genus in its own family, Paulowniaceae. Depending on the classification, it includes between six and seventeen species, most of them native to China. It was named in honour of Anna Pavlovna, daughter of Tsar Paul I of Russia and later queen of the Netherlands.
It goes by many names: princess tree, empress tree, foxglove tree, and kiri in Japan, where the paulownia flower is the emblem of the government and the Prime Minister’s office. The tree has very large leaves, especially when young, and clusters of lilac, bell-shaped flowers in spring, before the leaves open.
The best-known species are P. tomentosa, P. elongata and P. fortunei. Most timber plantations today grow selected hybrids of these species, such as P. elongata × P. fortunei.
Why it grows so fast
Paulownia is among the fastest-growing trees in the world. Two things explain its reputation:
- Early growth. In good conditions, young trees put on height and diameter very quickly in their first years.
- Regrowth from the stump. Cut at ground level, it sprouts again from the roots. The US Forest Service records root sprouts growing more than 5 m in a single season. Plantations use this: after the first year, the young tree is cut back so a single straight, vigorous stem can grow.
That speed has a consequence for the wood. Research on the Cotevisa 2 hybrid in Spain found that wood from the first rings is less stable, and that it becomes calmer and more even from around the fifth ring. Age matters: not all Paulownia is equal.
The wood: main properties
| Property | Value | What it means |
|---|---|---|
| Density | 260–280 kg/m³ (dry) | One of the lightest commercial timbers. Balsa is lighter; pine is roughly twice as heavy. |
| Hardness | Janka about 1.3 kN | Soft. It dents easily, so it is not used for floors. |
| Shrinkage | small (volumetric about 6–9%) | It moves little and evenly when it dries, so it stays flat and stable. |
| Workability | very easy | Cuts, planes, glues and takes screws well. Needs sharp tools. |
| Durability | low outdoors | Not durable against blue-stain fungi and sensitive to termites. It needs protection outside. |
| Appearance | pale, straight grain, few knots | Light blond colour and a clean, even look. |
Values vary with species, hybrid, age and growing site. Sources: CETEBAL laboratory reports on Cotevisa 2 (2012), Fos et al. (2023) and the Wood Database for P. tomentosa.
The combination is unusual: very light, but stable and easy to join. That is why it is sometimes called “the aluminium of woods”. It is not a structural timber, and it is not a wood for outdoor use without protection.
What it is used for
Tradition in Japan and China
In Japan, kiri has been prized for centuries for tansu chests and kimono boxes, geta sandals and the soundboard of the koto, a traditional string instrument. There is an old custom of planting a paulownia when a daughter is born, so that its wood can be made into a chest for her kimono when she marries. In China, Paulownia has long been planted alongside crops for its fast growth and light shade.
Today
- Surfboards and water sports: skins, rails and frames of hollow wooden boards, and wood layers in modern boards.
- Musical instruments: electric guitar bodies and soundboards.
- Lightweight panels and furniture: cores for panels, drawers, boxes and boats.
- Other uses: beehives, carving, model-making, veneer and packaging.
For how it is used in surfboards, read Paulownia wood for surfboards: the builder’s guide.
Myths and facts
Paulownia is often sold with claims that do not hold up. Here are the most common ones.
“It absorbs ten times more CO₂”
Unproven. Paulownia stores carbon quickly while it is young, but published figures vary enormously by site and management. The most extreme ones trace back to rough estimates. We don’t use a number.
“It is a C4 plant”
False. A 2023 study in Plants, People, Planet found that Paulownia’s physiology is that of a C3 plant, like most trees. The C4 claim spread through repeated, inaccurate citations.
“It doesn’t burn”
Not demonstrated. You will read that it ignites at around 400 °C. We have not found a laboratory source for that figure. In Japan, kiri chests are traditionally said to protect their contents from fire, but that is tradition, not a test result.
“It is the lightest wood”
Not quite. Balsa is lighter. Paulownia is one of the lightest commercial timbers, and more stable than many woods of similar weight.
Is Paulownia invasive?
One species, yes. Paulownia tomentosa is considered invasive in the eastern United States, from Pennsylvania to Georgia and west to Missouri. According to the US Forest Service, a single tree can produce 20 million seeds or more a year. In Europe it appears on the EPPO Alert List and has become naturalized in several countries, mostly in urban and disturbed sites such as walls, pavements and railways.
Timber plantations in Spain mainly grow hybrids. In 2013, the Valencian regional forestry service certified the hybrid Cotevisa 2 as a sterile clone, with non-viable seed and no invasive behaviour observed in its experimental plantations. The species matters: a sterile plantation hybrid is not the same as P. tomentosa growing wild.
Paulownia in Spain and Europe
Paulownia began to be introduced as a plantation timber in Spain about twenty years ago. Most plantations grow hybrids selected for straight stems and good growth in Mediterranean conditions, on rotations of several years for timber. Research trials in Spain have measured growth and wood quality, and the results make one thing clear: yield and wood quality depend heavily on the site, the water available and how the plantation is managed. Brochure yields should be read with care.
We have worked with Paulownia for fifteen of those years, from the nursery to the board. Read our Paulownia story.
FAQ
What is Paulownia wood used for?
Traditionally for chests, sandals and musical instruments in Japan. Today for surfboards, guitar bodies, lightweight panels, furniture parts, boxes, beehives and boats, wherever light weight and stability matter.
Is Paulownia a hardwood or a softwood?
Botanically it is a hardwood, because it is a broadleaf tree. Physically it is very soft and light, with a Janka hardness of about 1.3 kN.
How fast does Paulownia grow?
It is among the fastest-growing trees, especially in its first years and when it regrows from the stump. Real growth depends on the site, water and management.
Is Paulownia invasive?
Paulownia tomentosa is invasive in the eastern US and is on Europe’s EPPO Alert List. Many plantations grow hybrids; Cotevisa 2 was certified sterile by the Valencian forestry service in 2013.
Is Paulownia good for outdoor use?
Not without protection. Laboratory tests found it not durable against blue-stain fungi and sensitive to termites. Sealed or finished, as in a surfboard, it performs well.
Why is it called the aluminium of woods?
Because it combines very low weight with good stability and strength for its weight, the way aluminium does among metals. It is a nickname, not a technical term.
Keep reading
Guide
Paulownia wood for surfboards: the builder’s guide
Density, stability and durability with lab data, and a real cut list for a hollow board.
Read →Sustainability
Is surfing sustainable? The green paradox of the surfboard
Foam, resin and surf travel: what the data say, and what really changes with a wooden board.
Read →Surf industry
How surfboards are made today: the industry behind the board
Factories in Asia, supermarket foam boards, CNC shaping and famous logos that no longer make anything.
Read →Build local
Build local: a different economy for surfboards
The design travels, the board is built near the wave. Where the idea comes from and where it falls short.
Read →From the tree to your board
We select and prepare the Paulownia for every part of the board, and cut the frame by CNC. You build it.
Sources
- Paulownia, Wikipedia (taxonomy, naming, traditional uses, Japanese emblem).
- US Forest Service, Fire Effects Information System. Paulownia tomentosa.
- EPPO. Alert List: Paulownia tomentosa.
- The Wood Database. Paulownia.
- CETEBAL – Centre Tecnològic Balear de la Fusta (2012). Reports P458, P554 and P555 on Paulownia Cote-2 (physical-mechanical properties, durability, machining).
- Fos M., Oliver-Villanueva J.-V., Vázquez M. (2023). European Journal of Wood and Wood Products 81: 819–831. doi:10.1007/s00107-023-01941-8.
- Young and Lundgren (2023). Study of photosynthetic physiology in Paulownia. Plants, People, Planet. Lancaster University repository.
- Generalitat Valenciana, Servicio de Ordenación y Gestión Forestal (2013). Certificate on the sterility of clone Cotevisa 2, PROFORBIOMED project.
- Forests 13(5): 700 (2022). Paulownia review, including Spanish plantation trials.
