Growing Royal Empress Tree (Paulownia) from Seed

Fast-Growing, Potentially Invasive

Royal empress tree (Paulownia tomentosa), also called princess tree or sapphire dragon, is hardy to zone 5b. It blooms in spring before leaf-out with fragrant purple flowers. Warning: Listed as invasive in several states—check local regulations before planting.

Seed Starting Protocol

1. Start seeds indoors in January.
2. Use seed flats with moist (not soggy) potting mix.
3. Surface-sow—press seeds in but do not cover; light required.
4. Suspend 40W shop light 4-6 inches above flats.
5. Run lights 24/7 for 3 weeks at 70-85°F.
6. Germination in 2-3 weeks.

Seedling Care

• Transplant to individual pots when handleable (use a pencil to lift).
• Grow under lights until frost-free.
• Harden off 10 days in shade before planting out.
• Plant in full sun, well-drained soil.

Growth Rate

Explosive: 10-15 feet in the first year under ideal conditions. Massive leaves (12-18 inches) create dense shade. Weak wood—prune for structure.

Invasiveness Note

Produces millions of wind-dispersed seeds. In the Southeast and Mid-Atlantic, it escapes cultivation aggressively. Consider sterile cultivars or native alternatives if invasiveness is a concern in your area.