How to Manage and ID Paulownia tomentosa

Introduction: Royal paulownia is a native of China gives a most dramatic, coarse-textured appearance, with its huge heart-shaped leaves and large clusters of lavender flowers in the spring. Paulownia flowers are borne before leaf emergence so they stand out nicely, especially against an evergreen background. With a rapid growth rate, Princess-Tree can reach 50 feet in height with an equal spread in an open landscape.

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. Woody seed capsules form in autumn containing up to two-thousand seeds. They persist through the winter. Seeds germinate readily in the landscape and wherever they are carried. Because of this ability to take over a site, it has been given invasive exotic tree status and planters are cautioned about its reproductive potential.

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 Branches: Trunk/bark/branches: bark is thin and easily damaged from mechanical impact; droop as the tree grows, and will require pruning for vehicular or pedestrian clearance beneath the canopy; not particularly showy; should be grown with a single leader; no thorns
Pruning requirement: requires pruning to develop strong structure

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 paulownia has 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 the stem should be clear to the first main branch at 6 feet or higher. This pruning process is especially important if you are wanting to sell the tree for its wood.

In Depth: Paulownia thrives best in deep, moist but well-drained soil, sheltered from the wind, and has become naturalized in many parts of the South. Fuzzy, brown flower buds form in early autumn, persist over the winter, and bloom in early spring. Buds may freeze in very cold weather and drop off. Woody seed capsules form in autumn containing up to two-thousand seeds. They persist through the winter. Seeds germinate readily in the landscape and wherever they are carried. Leaves 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. Its use in reclamation of the disturbed soils of surface mines grows yearly. The wood is highly prized for the manufacture of specialty items in Asia, and there is a brisk export business of logs to Japan. The export market has led to establishment of commercial plantations in the United States and the wood is said to be the "highest priced saw timber in the country at this time".