Brachychiton

( brack - ee - KYE - ton )

At-A-Glance Information

Brachychiton, commonly called Bottletree or Kurrajong, is a genus of evergreen and partly deciduous trees that needs full sun and little to moderate water. They are native to Australia and are grown for many of their attributes, including their flowers, fruits and seed pods, swollen trunks (for storing water during times of drought) and handsome foliage. These trees grow to reach between 14 and 100 feet tall when mature, depending on the climate, growing conditions, and species (they grow at slow to moderate rate). Use Kurrajong trees in the landscape to add interest, provide shade, or as specimen trees. Take care when planting these trees in your landscape, as the seeds have very small spines that can cause skin irritation.

Brachychiton Species and Varietals

The genus Brachychiton is a member of the plant family Malvaceae and includes 31 species. The genus name is derived from the Greek words for short (brachys) and tunic (chiton), referring to its loose seed coats. The best growing zones for these prized trees vary depending on the species; for more information, see the descriptions below. To find your zone, click here: Zone Map.

Brachychiton acerifolius (Sterculia acerifolia) (Flame Tree, Australian Flame Tree, Lacebark Tree, Illawarra Flame Tree)
This tree is deciduous, but only for a short period and grows well in zones 15-24, H1 and H2. It is hardy to 25 degrees Fahrenheit and reaches 60 feet tall and 30 feet wide with a strong, smooth green trunk and red bell-shaped to tube-shaped flowers produced in spring and early summertime.

Brachychiton australis (Broad-Leaved Bottle Tree)
Native to eastern areas of Australia, this species forms a small tree that reaches between 5 and 20 feet tall when mature. Bark is light brown with shallow lenticels and leaves are green and maple-leaf shaped.

Brachychiton bidwillii (Dwarf Kurrajong, Little Kurrajong)
This species of Bottle Tree is native to tropical regions of eastern Australia, and forms a small tree that reaches between 7 and 16 feet tall when mature. Flowers are bright reddish-pink, and bloom before leafout.

Brachychiton discolor (Sterculia discolor) (Queensland Lacebark, Pink Flame Tree, Scrub Bottle Tree, Hat Tree, Sycamore, White Kurrajong)
This tree loses its leaves for a brief period during the  and is best in zones 15-24. Reaching 40-60 feet tall and 30 feet wide, Pink Flame Tree has a bottle-shaped trunk and blue-green leaves that are white underneath. Bell-shaped pink flowers appear in summer and are dusted with hairs, as are the fruits.

Brachychiton gregorii (Desert Kurrajong)
These small trees are native to northern and  Australia, and is named for the explorer Augustus Charles Gregory, the first Surveyor General of Queensland. These trees typically reach between 10 and 39 feet tall at maturity, and produce bell-shaped pale yellow flowers with red margins.

​Brachychiton populneus (Sterculia diversifolia) (Bottle Tree, Kurrajong)
This tree grows well in zones 12-24 and is evergreen. It reaches 30-50 feet tall and 30 feet wide. The trunk is broad at the base and tapers farther up, hence the common name 'Bottle Tree'. Flowers bloom in clusters of white to pinkish in late spring, but are not very noticeable. It is used widely as a shade tree, screen, or windbreak.

Caring for and pruning Brachychiton Trees

Choose a sunny location in the landscape to plant your Kurrajong tree. The best time of the year for transplanting is in the warmer months, when the tree is actively growing. When installing, try to be careful to not damage roots. These trees can tolerate some partial shade if necessary, but will have a slower growth rate and not produce as many blooms. Ensure that soil is well-draining before planting. Sandy or loamy soils are best; these trees can be susceptible to issues with root rot diseases if soil holds too much moisture. If planting in overly clay soils, make sure to amend with plenty of organic material before planting. Apply a 2-3 inch thick layer of mulch around the base of the tree, keeping it a few inches away from the trunk to prevent rot issues. Doing so will help to retain soil moisture, regulate soil temperature fluctuations, and suppress weed growth. Water newly-installed plants regularly to help them to establish a healthy root system. Keep the soil constantly moist but not waterlogged during this period. Once they have gotten an extensive root system established, these trees are drought-tolerant, able to store extra water in their swollen trunks for use in times of water stress. Water mature trees during prolonged periods of dry weather to maintain health. Providing a deep watering once every two or three weeks should be sufficient for established trees in most situations. 

Brachychiton trees are not heavy feeders; fertilizing is not always necessary unless the tree seems to be suffering. The best time to fertilize is in the spring and summer when the tree is actively putting out new growth. Use a balanced, slow-release fertilizer. Dead or damaged foliage or branches can be removed as needed to maintain these trees' appearance and health. Light pruning is the only type necessary for these trees, as heavy prunings can cause unnecessary stress. The best time to prune Brachychiton trees is in late winter or early spring, just before new growth begins to be pushed out for the year. These trees may require protection from cold in climates that reach below 20 degrees Fahrenheit in wintertime. Use frost cloths or blankets to cover the tree's crown and its trunk during cold snaps. Younger trees grown in pots can be moved to a sheltered location during these times of cooler weather, or heat lamps can be used to control temperature around the tree. Brachychiton trees bloom best after cool winter temperatures, so in springtime when the weather does warm again, efforts to protect the tree will be well-rewarded.

Propagation

Brachychiton trees 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 Bottle Tree, follow the instructions below:

Propagating Brachychiton 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 Brachychiton 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. You will also, after a few weeks, need individual pots for each seedling that grows. Take care when harvesting the seed pods from your Brachychiton tree, as the seeds have a seemingly downy covering made up of many sharp spines that can cause skin irritation. Wearing gloves is recommended when dealing with the pods and seeds.
  2. Harvest your seeds in late summertime. The seed pods are pretty easy to spot, they're large and dangle from the 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 (or pick them up off of the ground), 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 a few weeks from sowing. Once you begin to see seedlings sprout and they are able to be handled, transplant them to their own individual pots. 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.
Brachychiton seed pods will turn dark brown-black and begin to split open when seeds are mature.
Brachychiton seeds.

Problems and Pests

Although Brachychiton trees are relatively resistant to pests and diseases, they can have issues from time to time with the following:
  • Root Rot
  • Woodpecker Damage
For more information on these problems, including how to solve them if they pop up, consult the following pages:

Gallery

These trees survive long periods of drought by storing extra water inside their swollen trunks.
These trees can add almost wonderland-like interest to landscapes.
Bottle Trees are commonly used as street trees in their native range.
Bottle Tree is paired here with Dasylirion, Kalanchoe, Senecio, and a Pittosporum hedge.
This Bottle Tree provides height to a water-wise tropical and succulent garden.
Kurrajong trees are at home alongside palms, succulents, and other architectural plants.
Bottle Trees make very interesting Bonsai specimens.
These trees can be grown in containers, but will not reach their full mature size.
These trees are commonly called Bottle Trees due to their swollen trunks' resemblance to a wine bottle.

Videos

Learn about an interesting, grafted variety of Brachychiton.
All about Brachychiton populneus.
How to grow Brachychiton trees from seed.
A large Brachychiton tree in Northern California.

Resources

Propagating a Queensland Bottle Tree
Brachychiton rupestris (Queensland Bottle Tree)
Brachychitons, The Australian Bottle Trees
Wikipedia: Brachychiton
The New Sunset Western Garden Book: The Ultimate Gardening Guide (2012) - Page 202, Brachychiton
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