Paulownia tomentosa

Paulownia tomentosa (Princess tree, Kiri, Pao tong, Empress Tree, Foxglove Tree, 桐, 泡桐)

This is one of the fastest growing trees on earth and can reach maturity in 10 years. However, as a result the branches are very brittle and tend to break off in high winds. The large leaves exacerbate this problem. Plant somewhere sheltered.

They usually flower when they are around 8-10 years old if grown from seed. The flower buds form before Winter. So a harsh Winter with cold temperatures and high winds can kill them off which will reduce the amount of flowers the following year.

Paulownia tomentosa sucks nitrogen from the ground around it and as a result the leaves are high in nitrogen when they fall in Autumn/Fall. They will not tolerate shade. So you cannot plant them under a canopy of other trees.

Paulownia tomentosa can be prunned heavily every few years to prevent it getting too big, so you can do this with any trees near the house. This also encourages very large leaf growth the following year. Some people cut them back to the ground for a tropical effect in the garden as they can grow 6 feet in a single year.

In the United States they are considered a weed because every seed pod has about 2,000 seeds and they populate waste ground readily. However they will not take over from native trees because of their lack of tolerance for shade.

Soil

Paulownia tomentosa grows in soils ranging from a pH of 4.5 (extremely acidic ranges from 0 to 5.1) to 7.5 (neutral ranges from 6.6 to 7.5). It is adapted to silt, sand, loam, silt loam, sandy loam, loamy sand, silty clay loam, sandy clay loam and clay loam soils, and prefers low fertility.

Growth

This is a irregular tree has a very fast rate of growth and has a single crown growth form, and has an ultimate height of 20m / 65.6ft and spread of 15.2m / 50ft. It can take 26-30 years to reach its ultimate height and has a lifespan of around 51-60 years.

Height at ...

• 20 years 18.3m / 60ft

Leaves

The leaves are green in Spring and Summer and green in Autumn. They are cordiform in shape with palmate venation, and the texture can be described as rough. The leaf has an entire margin with an acuminate tip and a reniform base.

Aspect, exposure and elevation

The plant prefers a sheltered situation and grows well in all aspects. It grows 671m / 2,201ft below sea level in its natural habitat.

Scent

A moderate pleasant scent is emitted from the flower.

Toxicity

None in whole plant. Plant is very high in protein and can safely be fed to livestock.

Uses

Architectural, drought resistant, specimen/accent plant, forestry/timber and tropical effect.

Tolerances

Hedge (none), heavy pruning (high), wind (low), coppicing (high) and pollarding (high).

Fire

Very resistant to fire.

Bark, trunk, stem, roots and heartwood

Paulownia tomentosa has green bark with a rough texture. The trunk (bole) circumference at maturity is around 2m / 6.6ft, and the green stems have a smooth texture. The plant has brown structural roots, and the heartwood is cream coloured.

Fruit and seed

The seed is brown. There is a high fruit/seed abundance beginning in Summer and ending in Autumn.

Progagation and germination

Propagation techniques include bare root, container, cuttings and seed. The seed can be germinated by cold stratification / cold moist prechilling.

Origin

China (Central and Western).

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