Paulownia (Paulownia tomentosa) is also known as the "princess" or "empress" tree. The paulownia tree reaches 30 to 70 feet in height and its large, heart-shaped leaves are hairy on their undersides. This ornamental tree was brought to North America in the 1840s. Paulownia did not gain value as a tree until the lumber from it began to be in demand in Japan. Clusters of lavender flowers open in the spring on the paulownia and the seed capsules mature in the fall. Paulownia tree sprouts can reach up to 15 feet in height their first summer.
Remove the weeds in an area with direct sunlight exposure. Loosen the soil to the depth of 12 inches with a shovel. Break up the dirt clumps with the side of a garden hoe. Paulownia seeds require bare soil without any weed competition.
Spread 14-14-14 slow-release fertiliser at the rate of 1 pound per square yard over the soil. Mix the fertiliser in the top 8 inches of soil. The paulownia seedlings grow shallow roots so they can access to the fertiliser.
Rake the soil smooth and even. Sprinkle the planting area with water until the soil is moist. This allows the tiny paulownia seeds to stick to the soil. Scatter the tiny seeds over the soil at the rate of 1 teaspoon per square yard. It is best to do this by hand on a day without any wind, which can carry the seeds away.
Cover the planting area loosely with 2 inches of straw mulch. Mulching prevents the seeds from drying out through excessive moisture loss.
Place cheesecloth or fine cotton cloth over the straw mulch. Keep the material loose and anchor the edges with rocks or bricks. This keeps the seeds from being disturbed by splashing water and wind.
Water the seeds daily until the soil under the mulch is moist. Do not let the seeds dry out since this kills the seeds. Remove the cover when the paulownia sprouts are 2 inches tall. You do not want the seedlings growing through the cloth since this causes damage to the new trees when they are moved.
Paulownia seeds are stored in dry, airtight containers. Place the seed container in a cold area with temperatures of 3.33 to 4.44 degrees Celsius. The seeds last for four years in storage.
Paulownia trees produce seeds after reaching the age of eight to 10 years. Each seed capsule is filled with 2,000 seeds and a large tree produces 20 million seeds annually. The seeds are scattered on the wind in the winter and spring.