If you’ve travelled across Australia in summer, it’s almost guaranteed that the beautifully blooming bottlebrush has caught your eye. These incredible evergreen, attractive shrubs and trees are most recognised by their bottlebrush looking flowers, which are a rich source for local nectar feeders.
Remarkable and easily recognisable, the bottlebrush is a great option for growers as it’s almost impossible to kill and incredibly hardy, even in salt-laden soils.
So, if you’re considering adding the bottlebrush to your yard, here is some insight on everything you need to know to grow, cultivate and care for this incredible floral species.
What is a Bottlebrush?
The genus Callistemon or bottlebrush encompasses a range of blooming shrubs and smaller trees. Belonging to the Myrtaceae family, bottlebrushes are closely related to other Aussie favourites like melaleuca plants, eucalyptus plants and the Lilly Pilly.
Discovered by the renowned botanist Sir Joseph Banks, the Callistemon genus includes over 40 different species and many hybridised sub-cultivars.
This ornamental landscaping plant produces green, sometimes green-grey foliage and large, cylindrical flower spikes, which bloom with radiance throughout the summer season.
Depending on the variety, cultivars bloom in bright red, crimson, yellow, pink, cream and white.
Popular Bottlebrush Varieties
It’s easy to get overwhelmed when considering which kind of Callistemon to grow, as there really are so many options to choose from. Many of the varieties have a similar blooming habit or colour and still offer a certain sense of individuality.
Here are a few of our favourites:
Callistemon citrinus. Also known as the crimson bottlebrush or lemon bottlebrush. With show-piece red flowers, it’s known as the king of the bottlebrush family.
With a wide-arching canopy, the citrinus is a very popular choice.
Callistemon glaucus. The glaucus cultivar offers a wonderfully dense growth, perfect as a screening plant.
Also known as the Albany bottlebrush, it’s an incredibly hardy, suited for a range of climates and soils.
Most importantly, however, it will require full sun to bloom.
Callistemon brachyandrus. Also named the prickly bottlebrush, the brachyandrus cultivar grows curious yellow antlers that protrude out of the red flower.
Especially suited to the East Coast of Australia, this cultivar is incredibly adaptable in overly wet soils and humid conditions. Pruning is an essential part of this plant care.
Callistemon phoeniceus. Pretty in pink, the Phoeniceus is a bright and beautiful variety of the bottlebrush species.
Also known as the Scarlet bottlebrush, fiery bottlebrush or lesser bottlebrush. This is a smaller growing shrub and fairs particularly well in colder regions.
Callistemon viminalis. The weeping bottlebrush or Callistemon Captain Cook is one of the fastest-growing bottlebrush varieties.
It’s a large grower, often reaching as much as 5 meters tall.
Callistemon formosus. Perfect for more tropical areas, the formosus or Kingaroy bottlebrush is a fabulous, weeping variety with wonderful lemon coloured blooms.
Callistemon pityoides. Ideal for more compact spaces, the alpine bottlebrush is another yellow-bloomer with a very hardy growth habit.
How to Grow Bottlebrush
Callistemon plants are known to be fairly easy to establish and even easier to maintain. As these are known to be hardy plants, they generally tend to thrive even in not so optimal conditions.
The most important growth and callistemon care factors include the climate, sun, water and soil.
- Climate. The bottlebrush will grow quite happily in most climates, especially those in Australia. Depending on which variety you’re growing, extreme cold conditions are not always suitable.
Ideally, you’ll want to grow your bottlebrush in a temperate climate that receives regular summer rains. The best-known regions for bottlebrush growth include the tropical north or temperate south of Australia.
- Sun. It’s not new news that flowering plants need a decent level of sunshine to bloom. Bottlebrush plants can grow in both full-sun and semi-shaded conditions.
However, the more sun it receives, the more likely it is to bloom vigorously.
- Water. Younger and establishing plants will require regular moisture and water. As such, younger plants should be watered almost weekly, in the absence of rain.
Once established, however, it becomes incredibly drought-tolerant and can take a few weeks without needing water. Mulching at the base of the stem is a great way to help the soil retain moisture during particularly hot and dry spells.
- Soil. When it comes to soil, the bottlebrush is not particularly picky. However, ideally, you’ll want to have a rich, peat soil mixture.
For soils that are particularly poor, it is recommended to improve soil with some compost before planting. It is also incredibly tolerant of salty soils, so it can grow fairly easily in coastal regions.
Besides these features, your Callistemon should grow fairly happily and won’t require much more of your attention.
Depending on where you are growing your bottlebrush, in a pot or as part of a hedge, annual pruning can be done to control shape. Here is our review on the best garden secateurs for the job.
Propagating Bottlebrush Plants
Bottlebrush plants can be propagated by means of seeds and cuttings. Semi-hardwood cuttings can be taken in mid to late summer.
Cuttings should be 4 to 8 centimetres in length and include a few leaves at the end of the cuttings. The common planting method for cuttings can be followed.
After flowering, bottlebrush plants also produce a wealth of seed pods. These pods can be taken and stored until the seeds are released. Be sure to keep your seed pods in a warm, dry place for a few weeks.
Once released, seeds can be sewn into a rich seeding mix during the spring and summer.
When planting your bottlebrush into your garden, be sure to pick a semi-sheltered area that receives plenty of sunlight. Dig a hole that is twice the size of the root ball, tousle the roots lose, place into the hole and backfill.
It is recommended to create a smaller ring around the base of the stem, which will help the soil retain moisture. It is possible to grow your bottlebrush in a pot, especially the smaller and dwarf varieties.
When growing in a pot, it’s essential to pick the right spot and provide your plant with a rich yet well-draining potting mix. Tousle the roots lose before planting and pressing the soil down to remove air pockets.
Mulching with sugar cane or wood chips is also advised when growing in a pot.
Potential Bottlebrush Pest & Disease Problems
Bottlebrush plants are not often plagued or troubled by pests or infections. Sometimes, when conditions are sub-optimal for a longer period of time, it is possible for your bottlebrush to develop mould or be plagued by scale insects.
These can be easily treated with a horticultural spray.
The other issue, which has been raised by gardeners, is the threat of the Callistemon Sawfly Larvae, which invade and feed on the leaves of the bottlebrush.
For smaller invasions, it can generally be treated by a rigorous prune of all the affected foliage. For larger infestations, a caterpillar killer can be used to treat your plant.
Is the Bottlebrush an Australia Native?
The Callistemon is one of the most popular Aussie natives. In fact, it’s one of the hardiest endemic species that you can grow.
Is the Bottlebrush plant Poisonous?
Unfortunately, the leaves and seeds of the bottlebrush can be poisonous when ingested. As such, it’s absolutely essential not to ingest any parts of this plant and to use gloves when working with areas that may release sap.
In some instances, the ingestion of bottlebrushes can be fatal both for humans and livestock.
Can You Grow Bottlebrush as a Hedge?
Many of the lower growing cultivars, like the crimson and glaucus, are great options for flowering hedges. They are somewhat slower growing in comparison to other cultivars, and have dense foliage which provides a screening effect.
Be sure to have the best hedge trimmer handy by reading our review and buying guide.
Do Bottle Brush Trees have Invasive Roots?
The roots are slower-growing and are not considered to be invasive. As such, you can safely grow your bottlebrush along flower beds, walkways or walls.
Why is My Bottlebrush Dropping Leaves?
Browned, dried out and crumbled leaves are a sign that your bottlebrush could be in distress. This is usually caused by an extreme lack of water. Take care to monitor the level of soil moisture.
Start Growing Bottlebrush in Your Backyard today!
This endemic species offers an incredible range of bloom options, which you can mix and match as you choose. Plus, you’ll be able to enjoy all the additional garden visitors such as bees, butterflies and nectar-feeding birds almost year-round!
Whether you want a blooming garden plant, or a problem-free plant you can leave to grow in your garden – the bottlebrush or Callistemon is a perfect choice.