How to Manage and Maintain Paulownia tomentosa

A Valued Tree but an Exotic Invasive

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Paulownia with Fruit in Landscape. Westend61/Getty Image

An Introduction to Royal Paulownia:

Royal Paulownia is a native of China where it is revered as a tree and loved for both its legends and its usability. The tree's form is a bit ragged but can provide an enjoyable and dramatic, coarse-textured appearance with huge heart-shaped leaves and large clusters of lavender flowers in the spring. Paulownia flowers are usually set before leaf emergence so they really stand out against a neutral or evergreen background.

With its very rapid growth rate, the princess-tree can reach 50 feet in height with an equal spread in an open landscape.

Royal Paulownia Specifics:

Scientific name: Paulownia tomentosa
Pronunciation: pah-LOE-nee-uh toe-men-TOE-suh
Common name(s): Princess-Tree, Empress-Tree, Paulownia
Family: Scrophulariaceae
USDA hardiness zones: 5B through 9
Origin: not native to North America
Uses: reclamation plant; tree has been successfully grown in urban areas where air pollution, poor drainage, compacted soil, and/or drought are common
Availability: grown in small quantities by a small number of nurseries

Invasive Exotic Status:

Royal paulownia is a prolific seeder but not welcomed by many forest owners. Woody seed capsules form in autumn containing up to two-thousand seeds and can cover a large area using wind power. The seeds persist through the winter and have a high germination percentage. Seeds germinate readily in the landscape and because of this ability to take over a site, paulownia has been given invasive exotic tree status and planters are cautioned about its reproductive potential.

Royal Paulownia Description:

Height: 40 to 50 feet
Spread: 40 to 50 feet
Crown uniformity: irregular outline or silhouette
Crown shape: round; vase shape
Crown density: moderate
Growth rate: fast
Texture: coarse

Trunk and Branch Structure:

Royal paulownia's bark is thin and easily damaged from mechanical impact so be careful using equipment around the tree.

Paulownia has a characteristic droop as the tree grows and will require pruning for vehicular or pedestrian clearance beneath its canopy. The tree is not particularly showy and to improve its appearance, should be grown with a single leader. There is a major pruning requirement: the tree needs regular pruning to develop a strong structure.

Paulownia Foliage:

Leaf arrangement: opposite/subopposite
Leaf type: simple
Leaf margin: entire
Leaf shape: cordate; ovate
Leaf venation: pinnate; palmate
Leaf type and persistence: deciduous
Leaf blade length: 8 to 12 inches; 4 to 8 inches
Leaf color: green
Fall color: no fall color change
Fall characteristic: not showy

Pruning a Royal Paulownia:

The "Princess-Tree" expresses rapid growth and can reach 8 feet in two years from seed. This causes frequent winter kill to tender growth. You will not find this to be a problem if you prune down to where an axillary bud can take over as the single leader. It is important to build a single leader as long as possible and there should be a clear stem to the first main branch at 6 feet or higher. This pruning process is especially important if you are wanting to utilize the tree for its wood.

Royal Paulownia In Depth:

Paulownia thrives best in deep, moist but well-drained soil that is sheltered from the wind.

The tree has become naturalized in many parts of the southern United States so you can see them most anywhere in lower North American latitudes. Fuzzy, brown flower buds form in early autumn, persist over the winter and bloom in early spring. These buds may freeze in very cold weather and drop off.

Woody seed capsules form in autumn containing up to two-thousand seeds. They can easily hibernate through the winter and germinate readily in the landscape or wherever they are carried. Leaves rapidly drop within one week following the first frost in autumn.

Storm damage can be a problem as the tree is susceptible to breakage either at the crotch due to poor collar formation or the wood itself is weak and tends to break. It has no known insect enemies. There have been occasional reports of problems with mildew, leaf- spot and twig canker.

Royal paulownia was introduced into this country as an ornamental and it still retains some popularity for that purpose despite it being somewhat "messy".