Last Updated on September 20, 2020 by Kimberly Crawford
For gardeners or homeowners seeking a beautiful, unusual addition to their yard, the bottlebrush tree may be a perfect choice.
This plant, which is actually a shrub and not a tree, is native to Australia.
Because there are so many different varieties available, gardeners can choose the bottlebrush tree that suits their yard, climate, and taste the best.
Bottlebrush Tree Facts
Bottlebrush trees get their name from how their flowers grow in a cylindrical shape, much like a brush. The flowers, which are usually red, pink, orange, or white, are delicate and have an almost fluffy appearance. The plant’s leaves are narrow and light to dark green in color, and they often grow through clumps of flowers, giving the plant an even more interesting appearance.
Bottlebrush trees can become quite large, growing up to 15 feet tall, with flower clusters 12 inches long. However, they’re relatively hardy and can be pruned down quite a bit, so they can actually be grown in pots.
Although they are mostly found in Australia’s more temperate areas, these plants have been cultivated around the world and are now popular with gardeners in and out of Australia. In the United States, they grow best in hardiness zones eight through 11, although they are also a good choice for greenhouses because they can be grown in pots.
Types of Bottlebrush Trees
1. Crimson Bottlebrush (Melaleuca citrina)
As its name suggests, the crimson bottlebrush sports bright red flowers. This bottlebrush’s flowers and leaves are quite dense, so it’s a good option for a hedge. The branches themselves tend to arch a bit as the plant grows. The crimson bottle brush is also known as Melaleuca citrina, Callistemon citrinus, or Callistemon citrinus ‘Splendens.’
2. Weeping bottlebrush, creek bottlebrus (Melaleuca viminalis, Callistemon viminalis)
Melaleuca viminalis, also known as the weeping bottlebrush, also has bright red flowers. Because of its large, numerous blooms and the way the flowers and branches hang attractively, it’s one of the most popular bottlebrush choices for gardeners.
3. Stiff Bottlebrush (Callistemon rigidus)
Callistemon rigidus, or the stiff bottlebrush, features somewhat straighter and stiffer branches than those of the crimson or weeping bottlebrush. This particular plant is a popular choice for a hedge or container plant as it can be easily pruned and gardeners can keep it to between 3 and 8 feet tall.
4. Albany bottlebrush (Callistemon speciosus)
The Albany bottlebrush, Callistemon speciosus, thrives in the warm southwest of Australia and can generally be found along waterways. The flowers of this plant are red and the branches are long and stiff, standing upright. This plant is not quite as full as other bottlebrush trees. It can be pruned into shape and often resembles a tree rather than a shrub.
5. Lemon bottlebrush (Callistemon pallidus)
Callistemon pallidus, more commonly known as the lemon bottlebrush, has flowers that are much lighter in color than many other bottlebrush varieties. Although they can sometimes be pink, most lemon bottlebrush flowers are yellow or off-white. The branches of the plant are thin but stand upright.
6. Alpine Bottlebrush (Melaleuca pityoides)
Callistemon sieberi, the alpine bottlebrush, is a very full plant with narrow, almost pine-needle-like leaves. This is a smaller bottlebrush, growing only to between 3 and 6 feet tall. The flowers of the plant are pale yellow or off-white in color. These plants make an excellent hedge because it remains small and can be easily pruned into shape.
7. Cliff bottlebrush (Callistemon comboynensis)
Callistemon comboynensis, the cliff bottlebrush, closely resembles the crimson bottlebrush. The main difference is that the leaves of the cliff bottlebrush are somewhat wider in shape. As the name suggests, this plant can often be found growing along cliffs or outcroppings or wedged between rocks.
8. Wallum Bottlebrush (Melaleuca pachyphylla)
Melaleuca pachyphylla, the wallum bottlebrush, is native to the coast of Australia. This particular bottlebrush grows to about 10 feet tall, and the branches of the plant often trail instead of standing upright. The flowers are usually red but can sometimes be green in color. This is another popular choice as a hedge or barrier plant, as it is quite full.
9. Needle bottlebrush (Callistemon teretifolius)
Callistemon teretifolius is also known as the needle bottlebrush because its leaves are quite narrow and sharp. This bottlebrush grows to about 7 feet tall, and the flowers are generally red or orange with a greenish tint. Like most bottlebrush trees, this ornamental plant not only looks beautiful but will attract butterflies and hummingbirds to the garden.
Life Cycle of the Bottlebrush Plant
After planting, the seeds of the bottlebrush plant take between two weeks and one month to germinate. After sprouting, the young plant will need to be carefully cared for as it grows. It should be watered frequently, but care should be taken to ensure that the soil does not retain too much moisture.
The leaves of young bottlebrush trees will be delicate and will often have a strong, pleasant lemony or evergreen scent. Most bottlebrush varieties will begin flowering after about six years.
Most bottlebrush trees will grow about a foot each year, but smaller varieties will have a slower growth rate. Some, on the other hand, can grow up to 3 feet each year. Once the plant has matured, it will continue to produce both flowers and seeds for many years. Bottlebrush trees can live for up to 50 years, although most only live for about 40 years.
Bottlebrush Tree Care
Watering
Bottlebrush trees are largely drought-tolerant, and root rot is a common issue, so it’s important to only water this plant when necessary. Usually, mature plants growing outdoors won’t need any watering and will do well with rain alone. In drier climates, a layer of mulch can help to retain water and keep the soil moist.
Newly planted bottlebrush trees should be watered every day for a week after transplanting. Ensure that the soil is moist but dries somewhat between waterings. After the first week, they should only be watered about twice a week for the next month and can then be left without watering, as long as the rain is consistent.
Young bottle brush trees should be watered about once a week until they mature. When watering, soak the soil thoroughly but let it almost completely dry out before the next watering.
Light
Bottlebrush trees are used to a bright environment, so they thrive in full sunlight. These plants should receive about six hours of sun each day, although more sun each day is even better and will help flowers bloom to their full potential.
Temperature and Humidity
Bottlebrush trees prefer a mild climate and temperature. They do best when grown in areas that remain between 50 and 90 degrees Fahrenheit. If the temperature tends to dip below 50 degrees during the colder months, you may need to move your bottlebrush tree inside or grow it in a greenhouse. Frost can severely damage or kill a bottlebrush plant.
Low humidity is optimal for growing these plants.
Soil
When it comes to planting, bottlebrush trees can adapt to a wide variety of soils. Any soil that drains well will work. Peaty or loamy soils are often best, however. Any soil with a high amount of clay should be mixed with compost or another potting soil before planting.
Fertilizer
The pH of the soil you plant your bottlebrush tree in should be between 6.0 and 8.0. Compost works well as a covering fertilizer when planting. During the spring and summer, bottlebrush trees can also be fertilized once a month. A balanced, all-purpose fertilizer is often the best choice, but a fertilizer with a higher percentage of phosphorus can often produce larger, more colorful blooms.
Potting
Despite their large size, bottlebrush trees often grow well in pots. The pot doesn’t even need to be very big. A pot that’s about 8 inches across will work well, although the plant will need to be cut back often to keep its growth manageable.
These plants often grow well in much larger pots, however. A large tub or large ceramic pot is usually perfect. As the plant grows, you can transplant it to a larger pot as necessary.
When growing in a pot, ensure that there is plenty of drainage. You can add additional drainage holes to the container itself, and you can also place a layer of stones at the bottom of the pot. Mixing potting soil with perlite also helps with drainage.
Propagation
Bottlebrush trees are quite simple to propagate, either with cuttings or from seeds.
The fruit of the plant, where the seeds can be found, grows near where the flowers appear and looks something like a wide, round acorn. The fruit grows in cylinders, just as the flowers do. After harvesting the fruit, keep them somewhere dry and allow them to open naturally. Once split, the fruit will reveal many tiny seeds, which can be planted.
If you prefer to use a stem cutting to propagate your plant, cut the stem near the roots. Use sharp shears and ensure that the cut is clean and at a 45-degree angle to reduce any damage done to the parent plant. It’s also best to take cuttings during the summer so that the plant can heal quickly.
The cutting should be at least 6 inches long, but longer is also acceptable. Cut away any flowers and leaves. The cutting can then be placed in water or soil with the cut end submerged or buried. Change the water frequently to avoid any bacteria. The cutting should begin to root within about two or three months.
Pruning
Unless you’re keeping your bottlebrush tree in a pot, you shouldn’t need to prune it very often or very extensively. However, pruning can help to direct the plant’s energy into producing more flowers and can also allow you to shape the plant as you like.
If you’re pruning the plant to gently shape it, prune in the spring, before any flowers have appeared. You can prune the plant into nearly any shape, including a hedge or tree shape. Always make your cuts clean, with a sharp pair of shears, and cut just above a growth node to promote speedy healing.
Bottlebrush trees should also be pruned periodically to remove any dead or dying branches. This can also be done in the spring, or you can wait until late summer after the plant has bloomed. Any suckers near the roots can also be trimmed away.
Transplanting
Because they are hardy plants, bottlebrush trees often transplant well, but care should still be taken.
Before transplanting, water the plant heavily and let the water sink in to help loosen the soil. Then, measure the plant’s trunk at about 6 inches from the ground, and multiply this by nine to find the circumference of the roots.
Measure out where the roots are likely to be and dig in a circle around them. For mature plants, you will likely need to dig about 20 inches straight down in order to avoid hitting the roots. Don’t worry about severing any root tendrils, as long as the root ball stays intact.
Keep the plant in the shade until you’re ready to replant. When planting, try to orient the plant the same way, so that it’s facing the same direction it was in its last location.
When transplanting from a pot, always be as gentle as possible. Cut away containers when possible, or gently wiggle the plant back and forth until it comes loose. You can also loosen the roots if they have become at all bound while in the container.
Growing Problems
Bottlebrush trees should grow about a foot a year until they’re mature. If your bottlebrush tree isn’t growing or flowering, it could be due to several issues.
Lack of light is often the biggest hindrance to bottlebrush tree growth. Other plants can cast too much shade on the bottlebrush tree, so you may need to cut other plants or shrubs back or move the bottlebrush tree to an area that gets more constant, full sunlight.
An imbalance in the chemical levels in soil or the fertilizer you’re feeding the plant with can also disrupt growth. Nitrogen helps plants grow more leaves, so if the tree doesn’t seem full, you may need to up the nitrogen content in your fertilizer. However, more leaves often mean fewer flowers, so if your tree isn’t flowering, it may be because the nitrogen to phosphorus ratio is out of balance.
Pruning can also inhibit growth if it occurs at the wrong time in the growing cycle. Plants should not be pruned during the fall or winter, as this when they do most of their growing. You should also avoid pruning in late spring, as this can inhibit flower development.
Pests
Bottlebrush trees aren’t often bothered by too many pests, but pests such as web caterpillars, sawfly larvae, and scale insects can harm the plant. Both sawfly larvae and web caterpillars will defoliate the plant. Scale insects will suck the sap from branches, damaging the bark and leaves of the plant.
Neem oil and diatomaceous earth can often help to deter both scale insects and sawfly larvae. If web caterpillars are found on the plant, remove the web completely.
Diseases
Verticillium Wilt
Verticillium wilt is one of the more common diseases bottlebrush trees face. The disease causes leaves to curl up and turn brown. It’s caused by a fungus in the soil, so gardeners will usually spot dead or dying leaves at the base of the plant first, and the disease will migrate upwards.
It’s very difficult to remove the fungus that causes verticillium wilt from the soil. However, you can prune away any diseased branches and fertilize well. This should strengthen the plant, and the plant should, hopefully, be able to fight off the disease on its own.
Root Rot
Because it comes from a dry climate, the bottlebrush tree doesn’t tolerate excess moisture well. When the soil stays too wet for too long without drying between watering, fungus can grow. This fungus makes it so the roots of the plant can’t get the water they need.
Plants that have root rot will also often have yellow or brown leaves, and, eventually, the branches of the tree will begin to die. It’s almost impossible to solve root rot once it happens, so keep an eye out for soil that doesn’t drain well and watch for the early signs of the disease. Letting the soil dry completely can sometimes stop root rot.
Powdery Mildew
As the name suggests, powdery mildew looks like white, powdery mildew spots on the tree leaves or stems. This is another type of fungus that often attacks bottlebrush trees and usually occurs when trees get too much shade or moisture. The disease can be treated with a fungicide.
Twig Gall
Twig gall is another moisture problem that results in a fungal infection. Twig gall looks like round, papery balls around thinner parts of the tree’s stems. Some gardeners may at first think an insect has built a nest on the branches.
To treat twig gall, cut away any branches or stems that have this appearance, and ensure that the soil drains more evenly and that the plant is no longer overwatered.
Leaf Spot
Leaf spot often attacks ornamental plants, such as the bottlebrush tree. Usually, the disease, which is caused by a fungus, attacks only a handful of the tree leaves. It causes small brown dots to form on the leaves, and this interrupts photosynthesis. Leaf spot usually isn’t an incurable condition, but it can seriously harm the plant’s health if it attacks more than half of the plant or if it reoccurs yearly.
To treat leaf spot, make sure the tree gets enough sun and isn’t exposed to excess moisture. Prune away any browned branches, as these are branches that are probably not getting enough light, and they are therefore more susceptible to leaf spot. Also, rake away any fallen leaves.
Frequently Asked Questions
How Big Does a Bottle Brush Tree Get?
Bottlebrush trees grow to about 15 feet tall, although some can exceed 25 feet when properly cared for. They can be anywhere from 3 to 20 feet wide. Some dwarf bottlebrush tree varieties grow to only about 3 feet tall. Bottlebrush trees can also be heavily pruned if you prefer to keep them in a container or a smaller area.
Is Bottlebrush Poisonous to Dogs?
Ornamental bottlebrush trees, native to Australia, are not toxic to dogs. However, it’s still not a good idea to let your pets eat any parts of the plant. Be sure not to confuse Australian bottlebrush trees with the bottlebrush buckeye, which is native to the United States and not a true bottlebrush tree. Bottlebrush buckeyes are very toxic to pets, including dogs.
Is Bottlebrush Poisonous to Humans?
Bottlebrush trees are not poisonous to humans. In fact, some people even occasionally use the leaves to make tea. Many people believe that the bottlebrush tree is toxic but they are often confusing it with the North American bottlebrush buckeye, which is a completely different plant and is indeed toxic to humans.
Are Bottlebrush Roots Invasive?
Bottlebrush roots are generally not invasive and reach out about as much as any shrub’s roots would. However, it’s always a good idea to be cautious when planting a bottlebrush tree near a structure. The trees can become very large and the roots or branches have the potential to damage the structure.
How Long Do Bottlebrush Trees Live?
Bottlebrush trees tend to live for between 20 and 40 years when well cared for.
For gardeners who are looking for something truly unique, the bottlebrush tree is a fantastic choice. This plant is hardy and relatively easy to care for, and although it can become quite large, it can also be trimmed to fit into a pot. The many varieties of this plant also give gardeners a chance to choose from several different flowers to find the one that suits their yard the best.
Conclusion
These tips will set you up for success for caring for your bottle brush tree. I hope you enjoyed the article and you get busy planting!
For more gardening guides, check out our homepage. There are also other great guides for gardening for beginners.