Why aren't all Paulownia woods the same?

Cultivation of the paulownia has been on a roll in recent years. Often touted - and promoted - as an almost magical tree, capable of growing like Jack's beans in almost any condition. We've met planters in Europe and Asia and have been handling wood from various paulownias for almost a year at the time of writing.

Here are our findings:

There's no point in running...

Paulownia is a natural champion of growth. It optimizes photosynthesis and water consumption to provide more biomass than any other tree in a given time.

Some hybrids have been developed that are capable of even faster growth, even under space constraints, which means that - in theory - they can be planted more densely.

Problem: these trees are built on a less dense honeycomb structure and grow taller, to the detriment of increasing their diameter in search of light.

Whereas Asian paulownia (from the Tomentosa line) will produce wood with an average density of 300kg/m3, some wood from paulownia planted in Europe can have a density of around 220kg/m3. In addition to their fragility and lower strength, they can be more difficult to work with due to their porosity.

True, they grow very quickly (around 7 years to create 1m3 of biomass), but in our opinion their wood is too fragile to be used for most common applications.

Trees that grow too quickly are also more prone to storms; less solid, they are more likely to break during strong wind events...

Value can sometimes be measured in years. (even for paulownia)

Even more problematic is the fact that high plantation densities (up to 800 trees per hectare) tend to produce very tall trees with very small diameters, which again does not correspond to the standards of the timber industry and is likely to have the effect of greatly reducing the value of the wood produced. We also saw trees whose growth had stopped in the 6th year, probably due to lack of space in over-dense plantations.

Paulownia wood is highly sought-after in Japan, and has been paid for at a premium for centuries. But its value is strongly correlated with the tree's growth duration, the most sought-after wood having relatively close growth circles.

We believe that paulownia wood has a definite future as a renewable, lightweight and aesthetic wood supplier, and could help limit pressure on other species while storing CO2 very quickly. However, we probably need to give nature time to do its work and respect a few basic rules, which is unfortunately not always the case.