Paulownia

( paw - LOH - nee - uh )

At-A-Glance Information

These hardwood trees are commonly called Princess Tree, and are native to eastern areas of Asia. Individual trees reach full maturity in under 10 years and produce strong, lightweight timber, with a higher strength to weight ratio than Balsa wood. The blooms are followed by seed capsules, which remain on the tree, hanging alongside the next season's buds. These are popular street trees in their native range, and are also planted as ornamental trees, though some consider the seed pods that follow blooms to be unattractive. Take care when planting these trees in the garden, as the fruits are slightly poisonous if ingested, and bark can be toxic to dogs if ingested in large amounts. These trees also have the potential to be invasive in North America, so check your local authority before planting.​

Paulownia species and varietals

The genus Paulownia is the type member of the plant family Paulowniaceae and includes 17 species of hardwood trees. The genus was named in honor of Anna Pavovna, queen consort of the Netherlands. These trees grow well in zones 1-25 and H2. To find your zone, click here: Zone Map.

Paulownia catalpifolia
These trees are native to Shandong Province in China, and have been introduced to Hungary. These are extremely fast-growing trees and are cultivated in their native range as a source of timber.

Paulownia coreana (Paulownia glabrata) (Korean Paulownia)
This species is endemic to South Korea and reaches a height of between 50 and 66 feet tall. Flowers are light purple and bloom from May to June in the tree's native range. These trees produce good lumber, which is commonly used for making furniture, athletic goods, and musical instruments.

Paulownia elongata (Pink Empress Tree)
These impressively fast-growing trees produce very large, fuzzy leaves and can withstand a wide variety of environmental conditions. This species is commonly cultivated as an ornamental landscape tree, and is valued for its purple flowers and shade tolerance. Typically, trees can grow up to 15 feet in the first year of growth and can reach a harvestable size in just five to seven years.

Paulownia fortunei (Dragontree, Dragon Tree, Fortune's Empress Tree)
This tree species is native to China, Laos, and Vietnam, and is extremely fast-growing, though is less invasive than Paulownia tomentosa. Flowers are typically purple-pink, but can also be light-colored to white with pink throats. Variety 'Fast Blue' ('Minfast') is a popularly grown ornamental cultivar.

Paulownia kawakamii (Sapphire Dragon Tree)
This species is native to Taiwan, eastern China, and Japan and produces a wonderful show of purple to violet-colored flowers in early spring before leafout. These trees are considered to be critically endangered and are threatened by habitat destruction in their native range. These plants are widely cultivated as garden ornamentals for their gorgeous flowers, and is deep rooted, making it perfect for planting near sidewalks or other paved areas.

​Paulownia tomentosa (Princess Tree, Empress Tree, Foxglove-Tree)
These trees are native to China, and grow well in zones 4-9 and 11-24. Leaves are large and light green, and flowers are interesting, giving the tree an overall tropical look. Flower buds appear in fall and open in springtime, revealing trumpet-shaped lilac-blue flowers marked with spotting and stripes.​

Caring for and pruning Paulownia Trees

These beautiful, fast-growing landscape trees do well in full sun, but they can also tolerate partial shade. For optimal growth and foliage color, make sure that the tree receives between 6 and 8 hours of direct sun each day. These trees can grow to be quite large, so make sure that the chosen planting site has enough space to allow for the full size of the tree. They also have deep roots, and will not do well in compacted soil or if planted over a hardpan area. These trees will create litter, so plant them in an area where this will not be an issue. The roots and amount of shade this tree casts make it a poor tree to garden under. They can reach widths of 25-30 feet when mature, and reach 33-82 feet tall. These trees prefer moist but well-draining soil that is slightly acidic to neutral with a pH of between 5.5 and 7.0. They can tolerate a wide variety of soil types, as long as they are well-draining, but do prefer loamy soil. Apply a thick layer of mulch around the base of trees to suppress weed growth, increase soil moisture retention, and help to regulate soil temperatures. Water new plantings regularly as they develop strong root systems. During dry spells, make sure to provide extra deep waterings. Established trees are somewhat drought-tolerant, but do perform best with consistent moisture. Water deeply, especially during long dry periods of the year, and allow soil to dry out somewhat between waterings to discourage fungal root rot issues.

These trees do not require heavy feedings and typically do well with a simple application of organic compost to their root zone yearly in springtime. If trees seem to be struggling or foliage is somewhat discolored, trees may benefit from an extra feeding with a balanced, slow-release fertilizer (such as a 10-10-10). Avoid over-fertilizing trees, as this can negatively affect their growth and development over time. These trees also don't require heavy prunings, and have a natural pyramidal shape. From an early age, if trees are cut back every year to every other year, this tree will produce a very shady canopy and larger leaves, but will not  flower as well. Prunings should focus on maintaining this form instead of changing it. In late winter or early springtime, remove dead, broken, or diseased branches and lightly shape the canopy by removing crossing or poorly placed branches. Don't prune off too much foliage at any one time, as this can damage the tree and open it up to attacks from pests and disease. Trees will need to be protected from strong, drying winds, but can tolerate air pollution well, making them great for urban environments.

Propagation

Paulownia can be propagated either by using cuttings or from seed. To ensure that your propagated plant will have the exact same qualities and characteristics as the parent plant, use the cutting method. If you would like to experiment and see what plant you can grow from seed, just keep in mind that it will not necessarily be the same as the parent plant. To propagate your Paulownia, follow the instructions below:

Propagating Paulownia by Cutting
  1. Gather your materials. You'll need a clean, sanitized, sharp pair of garden shears, rooting hormone, a pencil, and a 3-inch pot filled with well-draining compost or other organic material. If you don't have any potting medium on hand, you can make some. Just mix together equal parts (by volume) moss peat and horticultural-grade sand or grit sand.
  2. In spring or early summertime, choose the plant that you'd like to propagate. Ensure that this plant has had a good watering the night before, as this will improve the chances your cutting will take root. Cut one or more 6 inch portion(s) of the end of a non-blooming branch and strip the leaves off of the lower half. Make a hole in your planting medium by pushing your pencil into the soil. Dip the end of the stem in rooting hormone, and plant it in your pot. Fill in soil around the cutting to support it, but do not pack it down too much.
  3. Moisten with water, and ensure that the pot has good drainage. Your pot should be kept in warm, sunny conditions indoors (and not in direct sunlight). Water whenever your soil is dry under the top layer. After about four to six weeks have passed, your cutting should be rooted. When you notice new growth, you'll know you have roots.
  4. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring, when you can transplant it to its new home. Ensure that the last frost of the year has occurred before doing this, as it can seriously damage your new shrub.

Propagating Paulownia by Seed
  1. Keep in mind that the plant you get from seed will not necessarily mimic all of the characteristics of the parent plant. To propagate by seed, you will need a paper bag, a pot or tray filled with well-draining compost or other organic material, a spray bottle and a fork. If you don't have any potting medium on hand, you can make some. Just mix together equal parts (by volume) moss peat and horticultural-grade sand or grit sand. You will also, after a few weeks, need individual 3-inch pots for each seedling that grows.
  2. Harvest your seeds. The seed pods on Paulownia plants are pretty easy to spot, they're large and attach to branches, left behind after flowers have faded. Once they have dried out and begun to split open, you can harvest the seeds inside. Cut them off of the plant, placing them in a paper bag. Harvest as many as you can, and place the paper bag in a dry, cool, dark area. They will begin to split open and release the seeds contained inside. Once they have been released, take them out of the bag and put them in a container so you can work with them.
  3. Water your prepared seed tray or pot filled with soil, and ensure that good drainage is occurring. Place your seeds in your prepared pot or seed tray about a quarter inch to a half-inch under the soil surface. Cover them with soil and water with your spray bottle. Place your tray of seeds in a warm area that receives bright, indirect light. A greenhouse is the most ideal climate, but a planting tray inside a window will do as well. Germination usually takes 7-14 days from sowing. Once you begin to see seedlings sprout and they are able to be handled, transplant them to their own individual 3-inch pots, filled with the same potting medium as described in Step 1. Loosen the seedlings from the potting medium by digging down with the tines of your fork about an inch and a half, gently working the seedling up until it is out. Then, replant the seedling in its individual pot.
  4. Keep the seedling's potting medium moist, but not wet, by spraying the soil with your spray bottle. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring (after the danger of frost has passed), when you can transplant it to its new home.
Paulownia seeds are contained in seed pods that are borne in clusters.
Paulownia seed pods contain up to 2,000 tiny, winged seeds.

Problems and Pests

These trees are considered invasive in some areas, so make sure to check with local authorities before installing. They can also suffer from some issues themselves, including:
  • Leaf Miners
  • Weevils
  • Scab Beetles
  • Woodpeckers
  • Witches' Broom
For more information on these pests and diseases, see the following links:

Gallery

Korean Paulownia is used to make the Geomungo and the Gayageum musical instruments in Korea.
Flowers appear before leafout each year.
Use these trees in urban spaces to provide shade.
Paulownia trees have very large leaves.
Flowers are typically various shades of purple, pink and white. Throats are yellow or light-colored.
Bees are pollinators of these trees.

Videos

Learn all that you need to know about the Foxglove Tree.
All about Empress Trees.

Resources

Princess Tree: National Invasive Species Information Center
Paulownia tomentosa (Empress Tree, Princess Tree, Royal Empress Tree)
Wikipedia: Paulownia
The New Sunset Western Garden Book: The Ultimate Gardening Guide (2012) - Pages 477 - 478, Paulownia tomentosa
If you have any questions, comments, concerns, or photos you’d like to add to the gallery, please let me know by sending me a message using the button below!
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