Paulownia Tomentosa, commonly known as the Empress Tree or Royal Paulownia, is a deciduous tree celebrated for its remarkably fast growth rate and striking ornamental features. Native to China, this species has been widely cultivated globally, prized for its ability to quickly reach maturity, often adding 10 to 15 feet in height annually in its early years. The tree produces large, velvety, heart-shaped leaves that can measure up to 20 inches across, providing dense shade during the summer months. In the spring, before the foliage emerges, the tree is covered in showy, fragrant panicles of light lilac-purple, foxglove-like flowers. Beyond its aesthetic appeal, Paulownia is valued for its lightweight, durable timber, which is used in specialty markets for items ranging from furniture to musical instruments.
Site Selection and Soil Requirements
Successful establishment of the Empress Tree begins with careful selection of the planting location, as the species demands specific environmental conditions for optimal growth. Full sun exposure is required; Paulownia Tomentosa needs a minimum of six hours of direct sunlight daily, as it is highly intolerant of shade, especially as a young seedling. Planting sites should also offer protection from strong prevailing winds, which can easily damage the tree’s somewhat brittle wood and large, succulent young growth.
The Royal Paulownia is adaptable to a wide range of soil types, tolerating everything from dry, poor soils to more fertile compositions. However, it thrives best in a moist, deep, well-drained, sandy loam that facilitates rapid root expansion. Heavy, unamended clay soils should be avoided, as they inhibit drainage and can lead to root rot, a common cause of failure in this species.
The tree tolerates a broad range of soil pH, but the most favorable growth is observed in slightly acidic to neutral conditions, ideally between pH 6.0 and 7.5. Before planting, it is beneficial to test the soil and amend it with organic matter to improve drainage and nutrient content. Given its potential for rapid and substantial growth, adequate spacing is necessary, requiring considerable distance from structures or other trees to accommodate its mature canopy spread.
Planting Techniques
The ideal period for planting Paulownia Tomentosa is in the dormant season, specifically during early spring or autumn when the soil is readily workable. When planting a seedling or bare-root stock, the prepared hole should be dug at least twice as wide as the root ball or root spread, but only as deep as the roots themselves. This wider hole encourages the newly forming roots to spread laterally into the looser surrounding soil rather than circling in the planting pit.
It is necessary to ensure the root collar, the transitional area where the stem meets the roots, sits level with the surrounding soil surface. Planting the tree too deeply is a common error that can lead to suffocated roots and poor establishment. After positioning the tree, backfill the hole gently with the excavated soil, tamping it lightly to remove any large air pockets that could dry out the roots.
Immediately following planting, a thorough watering is essential to settle the soil around the roots and begin the hydration process. During the first growing season, consistent moisture is important for developing a strong root system. Young plants require regular watering, often about 20 liters per plant weekly in the absence of significant rainfall, to support their rapid initial growth and prevent desiccation.
Ongoing Maintenance and Pest Management
Once established, the Empress Tree becomes significantly more drought-tolerant, but continued attention to watering during prolonged dry spells remains beneficial, especially in summer. Fertilization is a maintenance practice, particularly for young trees, which benefit from a balanced granular fertilizer, such as a 10-10-10 NPK formulation. This should be applied in early spring as new growth begins, and then every four to six weeks throughout the active growing season to fuel the tree’s intense growth habit.
Paulownia is robust but can be affected by certain pests and diseases, most notably aphids, which tend to colonize new, tender shoots. These small insects can often be managed with a strong jet of water or an application of insecticidal soap to the affected areas. Fungal diseases like powdery mildew and fungal leaf spots may appear, particularly in humid or poorly ventilated conditions, and these are often mitigated by ensuring good air circulation and avoiding overhead watering.
Root rot poses a threat and is almost always the result of poor soil drainage or overwatering. The tree’s capacity for aggressive self-propagation is a concern in many regions where it is classified as an invasive species. Cultivators have a responsibility to monitor the tree for unwanted seed spread, as a single tree can produce millions of tiny, wind-dispersed seeds.
The tree is known for root sprouting and suckering, making manual removal of the entire root system necessary to prevent regeneration. If the tree must be cut down, applying a concentrated herbicide solution, such as glyphosate or triclopyr, directly to the freshly cut stump is required to inhibit vigorous resprouting from the root crown. Routine structural pruning, involving the removal of dead, diseased, or crossing branches, should be done in late winter to maintain a healthy form and improve canopy light penetration.
Specialized Pruning for Rapid Growth
Beyond standard structural care, Paulownia Tomentosa is suitable for intensive pruning methods aimed at specific outcomes, such as maximizing leaf size or encouraging straight timber growth. One technique is coppicing, which involves cutting the tree down to a stump near ground level, ideally in late winter or early spring before bud break. This annual cut forces the tree to produce new, vigorous shoots from the root crown.
The resulting regrowth is characterized by single, straight stems that grow fast, often producing leaves reaching sizes of two feet across. This method creates a striking, tropical foliage effect but prevents flowering, as the tree is cut back before producing flower buds. Coppicing is also used in biomass production, where the focus is on maximizing the volume of rapidly renewable wood.
Pollarding is a technique where the main branches are cut back to a permanent trunk height, creating a framework or ‘knuckle’ of wood. This method is performed on established trees and can be repeated annually in the dormant season. Pollarding controls the tree’s height and encourages a dense head of new, vigorous growth, also resulting in larger-than-average foliage.