Callistemon | How to Select, Grow and Care for Your Bottlebrush

Callistemon or bottlebrush is a native of Australia, but due to its beauty, it is now cultivated in other places. It got its bottlebrush name because of its cylindrical and brush-like flowers, which look like a bottle brush for cleaning bottles. 

Callistemons are excellent garden plants, bringing vibrant colours to your landscape. Most flower spikes are red, but they come in other colours as well as pink, yellow, purple, green, or white. These colourful and beautiful flower spikes usually appear in spring and summer. Birds, bees, butterflies, and other insects find the spikes of flowers attractive because of their nectar. 

Just like the flower spikes, the leaves of Callistemon are gorgeous as well. They are covered with soft hairs that help gather moisture and are usually dark green in colour. To protect against dry and hot periods, the leaves don’t lose much water. The leaves are long, thin, and fragrant, releasing a mint scent. 

Mostly found in the more temperate regions, there are also species of Callistemon found in Tasmania and Western Australia. They thrive in wet or damp conditions and are generally healthy shrubs. Most species of Callistemon are resistant to frost.

Callistemon

 

Callistemon

Common Varieties of Callistemon or Bottlebrush

Slim Callistemon or Slim Bottlebrush

Callistemon viminalis, or Slim Callistemon, is native to New South Wales and Queensland, Australia. But it is perfect as well in South Australia, Victoria, Australian Capital Territory, and Tasmania. It has greyish-green foliage and red flowers. Giving constant and contrasting colours to your property, it produces flowers all year long.

Slim Callistemon got its name from its slender form and is often found along streams and creeks. An evergreen, it loves the heat and is also not prone to leaf burn. It is drought-tolerant once established in its planting place. It is also highly resistant to myrtle rust disease.

Slim bottlebrush is the solution for tight planting areas as it grows up to 3m high and 1.3m wide only. Perfect for a privacy screen and hedge, the best planting density is 1-3 bottlebrushes per square metre or 1-1.5 per linear metre. 

  • Location: Full sun.
  • Soil: Well-drained, slightly acidic soil. Avoid alkaline soils.
  • Watering: Water generously during the first year to establish the roots. Once established, water moderately.
  • Pruning: Prune in late summer to early fall to maintain its shape after flowering.
  • Feeding: Use a slow-release fertiliser in early spring.

Better John Callistemon or Better John Bottlebrush

Better John Callistemon is low-maintenance and quick to establish after planting. It grows up to a height of  60cm – 120cm and width of 60 – 90cm. The best planting density is 1.5 – 2 plants per linear metre or 3 – 5 plants per square metre. It is best in Queensland, Australia Capital Territory, New South Wales, South Australia, Western Australia, Victoria and Tasmania.

Also an evergreen, Better John’s young leaves have silver tones because of its soft hairy texture and turn bluish-green when they mature. It starts flowering with small dark red flowers from the middle of spring until late spring.

Better John Callistemon is best for borders, rock gardens, and hedges, but you can also grow them in containers. They can be accent plants or centrepieces because of their bright colours.

  • Location: Full sun to partial shade
  • Soil: Well-drained and sandy soils.
  • Watering: Once established, water occasionally.
  • Pruning: If needed, prune every 3 – 4 years for a natural form or every 2 years for a neat hedge.
  • Feeding: Use a slow-release fertiliser in spring. 

MacArthur Callistemon or MacArthur Bottlebrush

MacArthur Callistemon has a compact growth habit, growing up to 1.8m high and 1.5m wide. It is a medium-sized shrub that has a tidy growth. The recommended planting density is 1 – 2 plants per square metre or 1 – 1.5 plants per linear metre. 

Highly versatile, MacArthur Callistemons tolerate drought and frost. They can be found in Queensland, Australian Capital Territory, New South Wales, Tasmania, Victoria, South Australia, and Western Australia.

This bottlebrush is an evergreen that has long but narrow green leaves. In spring, it showcases large bright red flower spikes. You can use this as a feature plant in your garden or as hedges, erosion control, or windbreaks.

  • Location: Full sun to partial shade.
  • Soil: Adaptable to most soil conditions.
  • Watering: Water generously for the first 8 – 13 weeks after planting. 
  • Pruning: Prune to maintain its shape about three times a year after flowering.
  • Feeding: Use a slow-release fertiliser in spring.

Flora Burst Callistemon or Flora Burst Bottlebrush

Flora Burst Callistemon has an abundance of red bottlebrush flower spikes in spring. Even when the entire Callistemon is enveloped in flowers, more flower buds are getting ready to open. In spring and autumn, it boasts of gorgeous rustic red new growth.

Flora Burst Callistemons can be used as hedges, feature plants, and mass plantings. They grow up to 2, high and 1.5m wide. The planting density is suggested to be 1 – 2 plants per square metre or per linear metre. They can be found in Queensland, Australian Capital Territory, New South Wales, Tasmania, Victoria, South Australia, Western Australia, and Northern Territory.

  • Location: Full sun to partial shade.
  • Soil: Adaptable to most soil conditions.
  • Watering: Water generously for the first 8 – 13 weeks after planting. 
  • Pruning: Prune to maintain its shape about three times a year after flowering.
  • Feeding: Use a slow-release fertiliser in spring.

Dawson River Weeper Callistemon

Dawson River Weeper Callistemon is a tall shrub that is perfect as a privacy screen. It grows up to 6m tall and 4m wide. An evergreen, this is a fast-growing weeping plant as it droops towards the ground. Unlike other Callistemons, Dawson River Weeper doesn’t like an extended period of droughts.

It has long, pendulous branches with soft grey to green leaves that are covered in silky hairs. In spring, it produces an abundance of scarlet red flower spikes that are up to 90mm long. It also flowers during other times of the year, so you’ll have a year-round burst of colours in your garden.

  • Location: Full sun to part shade
  • Soil: Well-drained clay or sandy soil
  • Watering: Water regularly but allow the soil to dry out slightly in between watering.
  • Pruning: Prune to maintain its shape and to encourage new growth.
  • Feeding: Use a slow-release fertiliser or compost in spring.

Callistemon Citrinus or Crimson Bottlebrush

Crimson Bottlebrush has arching branches with sword-shaped leaves that are lemon-scented and coppery in colour when young before turning to greyish green. This Callistemon blooms sporadically all year and has bright crimson flower spikes that are 10cm long.

Growing up to 7.5m tall and 6m wide, Crimson bottlebrush is drought-tolerant. It makes excellent hedges and shrub border. It is found in Queensland, New South Wales, and Victoria. 

  • Location: Full sun to partial shade.
  • Soil: Well-drained, moist and acidic soils.
  • Watering: Water regularly, but do not over-saturate.
  • Pruning: Prune right after flowering.
  • Feeding: Use a slow-release fertiliser in spring.

Scarlet Flame Callistemon

The Scarlet Flame Callistemon is a compact shrub that has rustic red new growth in spring and autumn. It also produces bright red flowers, providing a cheerful look. It grows from 60cm – 1.5m high and 60cm – 1m wide. The suggested planting density is 1 – 3 plants per square metre or 1 – 2 plants per linear metre. 

Because of its small size and colours, it would make an excellent hedge. You can find this Callistemon in Queensland, New South Wales, Australian Capital Territory, Victoria, Tasmania, South Australia, and Western Australia.

  • Location: Full sun to partial shade.
  • Soil: Well-drained soil.
  • Watering: Water generously during the first year to establish the roots. Once established, water moderately.
  • Pruning: Prune in late summer to early fall to maintain its shape after flowering.
  • Feeding: Use a slow-release fertiliser in early spring.

Common Issues with Callistemon or Bottlebrush

Twig Gall

Twig gall is a fungal disease that one of the most common diseases of bottlebrushes. It is caused by overly wet soil and results in bloating of twigs. You can cut off the unhealthy and affected area. To prevent this from happening again, make sure that the soil is well-drained.

Powdery Mildew

Like twig gall, powdery mildew on bottlebrushes is a result of excess water on the foliage. As a remedy, use a fungicide spray. To prevent powdery mildew, water the plants from below and not from above as is customary. 

Root Rot

Like twig gall, root rot is caused by excess water in the soil. Callistemons need well-drained – not wet – soil. When the soil is too wet, the root rot fungus can damage the roots of the shrub and those of the neighbouring plants. The branches die, the leaves turn yellow, and the trunk shows peculiar colours. To treat root rot, you have to apply fungicides. Make sure that your soil is well-drained to prevent this from happening again.

Verticillium Wilt

This is a plant disease that causes the Callistemon’s leaves to turn yellow and the branches to die. You can treat verticillium wilt with fungicides. You can also move the tree to a different location.

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