What to Plant with Callistemon: Native Companion Planting Guide

Have you ever wondered how to enhance the beauty of your callistemon, also known as bottlebrush? Companion planting might be the answer.

This article will explore the art of companion planting with callistemon, focusing on native Australian plants that can complement and thrive alongside this vibrant shrub or small-to-medium tree.

Understanding Callistemon: The Bottlebrush Plant

Callistemon is a genus of shrubs in the Myrtaceae family, native to Australia. Known for their cylindrical, brush-like flowers (hence the common name ‘bottlebrush’), callistemon species are a favourite in many Australian gardens due to their hardiness and striking appearance.

These plants have specific needs and conditions for optimal growth. They prefer well-drained soil, full sun to partial shade, and while they can tolerate dry spells once established, they appreciate regular watering during prolonged dry periods.

Ecologically, callistemon plays a significant role in supporting local wildlife. Its vibrant flowers are rich in nectar, making them a magnet for pollinators like bees and birds. Moreover, the dense growth habit of some species provides shelter and nesting sites for various bird species.

Choosing the Right Companions for Callistemon

Choosing the right companion plants for your callistemon involves considering several factors. The companions should ideally share similar needs in terms of sunlight, water, and soil type.

Additionally, they should contribute to the overall health and aesthetics of the garden, either through their foliage, flowers, or ecological roles.

Remember that treating all plants of the same genus or even the same species the same is a mistake. Different varieties, even at the same species level, will perform differently in various conditions.

For example, Westringia spp. are generally thought of as sand-loving plants that hate wet feet, but Ozbreed have bred a couple that not only tolerate flooding, but thrive in it and grow several times as large as they should do (according to the mature height on the label) when they sit with wet feet for extended periods.

Learn more about our wet feet plant research here.

Melaleuca spp. as Wet Soil Companions

Melaleuca, commonly known as paperbark or tea tree, is a genus closely related to callistemon within the Myrtaceae family.

Melaleuca species are well-adapted to heavy clay soils, with many tolerating wet feet even better than callistemon. Additionally, some species’ bark, which peels off in papery sheets, can serve as natural mulch, keeping the soil cool and moist.

This paper bark also provides a sensory element within gardens, especially useful as a mindfulness tool for mental healing and as a way for children to connect with nature.

Ecologically, Melaleuca species play a somewhat similar role to callistemon. While their flowers are more subtle, they still attract a variety of pollinators.

Allocasuarina and Casuarina spp. as Soil-Improving Companions

Allocasuarina and Casuarina, commonly known as sheoaks, are two genera that make excellent companions for callistemon. While both genera are similar, Allocasuarina species are only found in Australia, compared with the internationally endemic Casuarina.

Many species within these genera thrive in clay-rich environments, just like callistemon. They aid in nutrient cycling, breaking down clay soils and improving their structure over time.

Although they aren’t related to legume family members, they can still fix nitrogen to the soil through the help of rhizobacteria. Some species can even thrive in saline conditions and improve sodic soil conditions.

However, it’s worth noting that some varieties may prefer sandy conditions to clay-dominant soils. Therefore, it’s crucial to choose species that are well-suited to your specific garden conditions.

Poa spp. as Habitat-Providing Companions

Poa, commonly known as tussock grass, is a genus of Australian native grasses that makes excellent companions for callistemon. These grasses are adaptable to a variety of conditions, including heavy clay soils, making them a versatile choice for many gardens.

In addition to enhancing the soil structure, Poa species provide habitat for beneficial insects. The dense clumps of foliage offer shelter and food sources for a variety of invertebrates.

In particular, native butterflies and moths often lay their eggs in native grasses, and their larvae (caterpillars) are very happy to munch on the leaves.

Their foliage dances on a windy day which can be quite mesmerising when you’re sitting in the garden with a cup of tea. Especially when you have mass plantings of poa and/or other clumping grasses.

It’s worth noting that many strappy-leafed monocots, like native grasses, dianellas and lomandras, have fibrous root systems that are particularly good at stabilising the upper layers of the soil profile.

Meanwhile, tree roots can help stabilise deeper layers. As the roots of callistemon don’t travel as deep as other trees such as eucalypts, incorporating them into the design is a good idea for sites with erosion issues.

Lomandra spp. as Erosion-Preventing Companions

Lomandra, commonly known as mat rush, is a genus of Australian native grass-like plants. These plants are compatible with callistemon, sharing similar preferences for sunlight and soil conditions.

Some varieties of Lomandra spp., particularly Lomandra hystrix varieties, are well-suited for clay soils and wet conditions. They assist in preventing soil erosion, thanks to their extensive root systems, and provide weed suppression with their dense growth habit.

Learn more about which plants are the best for controlling erosion here. https://www.ozbreed.com.au/category/plant-research/erosion-control-trials/

Dianella spp. as Garden-Diversity Enhancing Companions

Dianella, often referred to as Australian flax lily, is a genus of strappy-leafed plants native to Australia. Some cultivars are adaptable to heavy clay soils, making them suitable companions for callistemons in gardens that lack well-draining soil.

Planting Dianella spp. alongside callistemon can enhance garden diversity, offering a different texture and form to contrast with the bottlebrush flowers. Their attractive foliage and striking blue or purple berries also add visual interest to the garden.

Their flowers are a favourite of native buzz pollinators such as the blue-banded bee, which are able to unlock pollen from the flowers by vibrating at a specific frequency.

Leptospermum spp. as Heavy Clay Companions

Leptospermum, widely known as tea tree, is a genus of shrubs and small trees in the myrtle family. These plants thrive in clay-rich environments, making them compatible companions for callistemon.

Their small, needle-like leaves and distinctive, five-petalled flowers complement the visual appeal of callistemon, providing a pleasing contrast to callistemon’s bottle brush flowers in the garden. Both plants typically flower in spring and early summer.

Correa spp. as Year-Round Interest Providing Companions

Correa, often referred to as native fuchsia, is a genus of evergreen shrubs native to Australia. These plants are compatible with callistemon, sharing similar preferences for sunlight and loamy soil conditions. However, correas generally won’t tolerate heavier clay soils like some callistemons.

They provide year-round interest in the garden, thanks to their attractive foliage and bell-shaped flowers, which come in a variety of colours from white to pink and red. Additionally, they attract native fauna, including birds and pollinating insects.

Correas generally flower from autumn to early spring, providing a splash of colour when many other plants are not in bloom. On the other hand, callistemons typically flower in spring and early summer, so planting both of these plants together ensures your garden has vibrant colour throughout the year.

Xanthorrhoea spp. as Architectural Element Adding Companions

Xanthorrhoea, commonly known as grass tree or black boy, is an Australian genus of perennial plants. These slow-growing plants add an architectural element to the garden and are visually striking, making them excellent companions for callistemon.

Xanthorrhoea species are suited for clay loam soils as long as they aren’t too heavy and can withstand dry conditions once established. Their distinctive shape, with a tall, straight trunk topped with a tuft of grass-like leaves, provides a strong contrast to the bushy growth of callistemon.

However, it’s important to buy Xanthorrhoea from ethical suppliers. Many mature plants have been illegally removed from the wild, causing significant environmental damage. Always ensure that your plants are sourced responsibly.

Imperata spp. as Soil-Stabilising Companions

Imperata, also known as cogon grass, is a genus of perennial grasses that are ideal for stabilising clay banks and preventing soil erosion. Their dense root systems help to bind the soil together, reducing the risk of landslides and soil degradation.

Imperata species can tolerate wet and dry conditions, making them suitable for areas with periodic waterlogging and drought. They also filter silt runoff above the ground, helping to maintain water quality in nearby streams and water bodies.

Whether you’ve got heavy clay or sand-dominant soils, imperata grass can adapt and thrive. This makes them a great plant for bioswales along with certain Callistemon cultivars which have been shown to thrive with periodic wet feet and drought.

Learn more about which callistemons thrive with wet feet . https://www.ozbreed.com.au/summary-plants-in-various-wet-feet-conditions/

Hakea spp. for Nectar Feeding Birds

Hakea is a genus of shrubs and small trees native to Australia, known for their distinctive, often spiky, foliage and attractive flowers (which look remarkably similar to the flowers of their relatives, grevilleas). These plants are adaptable to poor soil quality but prefer draining soils including clay loams.

Just like most Proteaceae members, their flowers are frequented by nectar feeding birds, native mammals and beneficial insects. They also provide habitat for wildlife, including birds and small mammals, enhancing the biodiversity of your garden.

It’s worth noting that while callistemons can tolerate a general fertiliser, members of the Proteaceae family, like hakea and banksia, prefer a native fertiliser with low levels of phosphorous. High phosphorous levels can harm these plants, so it’s important to be careful of over-feeding with regular fertilisers and composts.

Westringia spp. as Garden-Aesthetics Enhancing Companions

Westringia, often referred to as coastal rosemary, is a genus of shrubs native to Australia. These plants are compatible with callistemon, sharing a similar bushy growth habit and preference for full sun.

They’re two of the best Aussie natives to use as a hedge.

Some cultivars of Westringia spp. are well-suited for heavy clay soils, while others prefer sandy conditions. Therefore, it’s important to read your plant labels and choose a variety that matches your specific garden conditions.

Both Westringia and callistemon contribute to a native bush aesthetic, providing a sense of cohesion and harmony in the garden. Their contrasting flower colours, with Westringia typically producing white or pale blue flowers, and callistemon producing vibrant white, red or pink flowers, can create a visually pleasing balance in your garden.

Boronia spp. as Fragrance-Adding Companions

Boronia, a genus of aromatic shrubs native to Australia, makes an excellent companion for callistemon. Just make sure that your soil has adequate drainage.

One of the standout features of boronia species is their fragrance. The flowers and sometimes leaves of certain varieties emit a pleasant perfume, adding an olfactory dimension to your garden. Moreover, the vibrant, often bell-shaped flowers attract a variety of pollinators, enhancing the ecological value of your garden.

Dampiera spp. as Garden-Diversity Enhancing Companions

Dampiera is a genus of flowering plants that can enhance the diversity of your garden when planted alongside callistemon. These Australian natives are well-suited to clay soils, making them compatible companions for callistemon.

Dampiera species are known for their stunning blue or purple flowers, which add vibrant colour to the garden. Their low-growing, spreading habit can provide a nice contrast to the upright growth of callistemon, creating a more visually diverse and interesting garden.

Kennedia spp. as Ground-Cover Providing Companions

Kennedia, a genus of climbing or trailing plants native to Australia, is another excellent ground-covering companion for callistemon. These plants tolerate heavy clay soils and are known for their ability to fix nitrogen, improving soil fertility over time.

Kennedia species form dense ground covers, helping to suppress weeds and reduce soil erosion. Their attractive, typically pea-shaped flowers also add visual interest to the garden, complementing the striking brush-like flowers of callistemon.

Why would you use boring bark chips as mulch, when you can incorporate a living mulch like this?

Brachyscome spp. as Visual-Appeal Enhancing Companions

Brachyscome, commonly known as native daisy bush, is a genus of flowering plants that can enhance the visual appeal of your garden when planted with callistemon. These plants are adaptable to heavy clay soils.

Brachyscome species produce daisy-like flowers in a range of colours, from white and pink to purple and blue. The soft, feathery foliage and cheerful flowers provide a striking contrast to the hardy, bushy growth of callistemon, adding variety and interest to your garden. Additionally, they attract a variety of pollinators, contributing to the ecological health of your garden.

They’ll flower at the same time as your bottlebrushes in spring and summer.

Hardenbergia spp. as Climbing Companions

Hardenbergia, often referred to as native wisteria or false sarsaparilla, is a genus of climbing plants that can make excellent companions for callistemon. These plants share similar needs and conditions, thriving in full sun to partial shade and well-drained clay soils.

Hardenbergia species are valued for their vibrant, pea-shaped flowers and attractive climbing habit. They can be used to add vertical interest in the garden, either by growing up a trellis or winding through other plants. Like many members of the Fabaceae family, Hardenbergia species can fix nitrogen in the soil, improving soil fertility over time.

Ecologically, hardenbergias attract a variety of pollinators and can provide habitat for small birds and mammals, enhancing the biodiversity of your garden.

If you’re using hardenbergia as a ground cover, be aware that it’ll want to climb up your callistemon. This will create excellent habitat for fauna, but may begin to starve your callistemon of sunlight and prevent adequate airflow around the branches.

This isn’t necessarily an awful thing depending on your gardening goals, in fact, it’s great for habitat, but it’s something to be aware of as it may not suit your aesthetic taste.

Incorporating Callistemon and Its Companions in Your Garden Design

Choosing the right companions for your callistemon can greatly enhance the structure and visual interest of your garden. Consider the growth habits, flower colours, flowering times, and ecological roles of different plants when planning your garden design.

When planting, ensure each plant has enough space to grow and spread. Regular watering will help establish the plants, but once established, many of these native companions are relatively low-maintenance and can tolerate dry spells.

In fact, overly saturated soils (especially heavy clay soils) can be a much bigger problem for many plants than dry conditions.

Don’t be afraid to experiment with different combinations based on your specific conditions and preferences. Trial and error is part of the gardening journey, and over time, you’ll develop a deeper understanding of what works best in your garden.

Daniel’s Wrap

Choosing the right companions for your callistemon is more than just an aesthetic decision—it’s a step towards creating a healthier, more diverse garden. Companion planting can improve soil fertility, attract beneficial wildlife, and enhance the overall health and resilience of your garden.

By planting densely and diversely, we can create better conditions for our plants and the native fauna they support. Don’t be satisfied with just a few plants, when you still have room to plant extras.

We hope this article has provided valuable insights into the art of companion planting with callistemon. Apply this knowledge in your own garden projects and witness the transformation. Happy gardening!