Bottlebrush: cultivation, plant care & more

Anika
Anika
Anika
Anika

I studied agricultural sciences and have always preferred spending my free time outdoors. Apart for my enthusiasm for gardening and agriculture, I love taking photos and rarely leave home without my camera. Whether it is landscapes, blossoms or wildlife, I can usually find a perfect shot that captures the beauty of nature.

Favourite fruit: strawberries, blueberries, plums
Favourite vegetables: radishes, tomatoes, pumpkin

Want to know how to properly plant bottlebrushes and what to pay attention to when caring for them? Find all the info about the bottlebrush plant here.

Bottlebrush
The striking inflorescences of the evergreen bottlebrush are reminiscent of bottle cleaning brushes [Photo: GiuseppeCrimeni/ Shutterstock.com]

Bottlebrushes (Callistemon) are very popular evergreen container plants. With their exotic inflorescences, they will transform your patio or balcony into a beautiful tropical oasis in the summer.

Bottlebrush: origin and properties

The approximately 35 known bottlebrush species belong to the myrtle family (Myrtaceae) and originate from Australia. In 1789, the bottlebrush arrived in Europe, and the genus Callistemon was described taxonomically for the first time in 1814. One of the most well known and popular Callistemon species is the crimson bottlebrush (Callistemon citrinus). The evergreen plant reaches heights of up to seven metres in its natural habitat in Australia. Bottlebrush plants also grow into stately bushes in Mediterranean regions. In temperate climates, on the other hand, they grow up to about three metres tall. The bottlebrush grows as an upright shrub or small tree with overhanging branches, which continually form striking flowers on their tips between May and September in up to four flowering seasons.

The cylindrical inflorescences are composed of single flowers arranged in spikes, with numerous long stamens projecting almost vertically outward. This creates the shape of a bottlebrush, the plant’s namesake. The crimson bottlebrush flowers appear in bright red. The flowers of other species bloom in various shades of red, orange, yellow and white. The leaves of Callistemon citrinus are lance-shaped, grey-green in colour and have a hard surface that protects the plant from excessive water loss through evaporation in its native habitat. In addition, the leaves contain essential oils that have a pleasant lemony scent when the leaves are rubbed between the fingers.

Planting bottlebrush

Since the bottlebrush is not hardy, it can only grow in planters in our region. This way, it can be brought indoors and overwintered in a suitable place. Finally, from April, when no more frosts are expected, the plant may leave its winter quarters and be placed outdoors. In accordance with the conditions of its natural habitat, the bottlebrush needs a lot of sun. Therefore, choose a location on your balcony or in your terrace or garden that has full sun and is warm and sheltered from the wind. In October, move the Callistemon back to a frost-proof place. The bottlebrush can also be kept year-round as a houseplant in the conservatory or in a light-filled room. However, you can expect less abundance of flowers because the plant will not have a proper dormancy period.

Bottlebrush plant with flowers in the garden
With the right care, the bottlebrush keeps forming new flowers [Photo: Olha Solodenko/ Shutterstock.com]

Choose a sufficiently large container in which to plant the bottlebrush so that its roots can develop well. Repot young bottlebrush plants into larger containers annually in spring. As for the soil quality, it is important to have good permeability, lime content that is not too high as well as a slightly acidic pH of the substrate. Peat-free potting soils, such as our Plantura Organic Flower Compost, are ideal. To increase the proportion of coarse pores, thereby improving the drainage capacity, expanded clay or lava chippings can also be added.

Plantura Organic Flower Compost
Plantura Organic Flower Compost

Peat-free & environmentally-friendly:
for flower beds & plant pots,
ensures beautiful plants that flower all summer,
100% natural ingredients

Tip: Young Callistemon is susceptible to root rot. Therefore, a high-quality, permeable substrate is particularly important.

Bottlebrush care

If you properly care for a bottlebrush you will be rewarded with a lush abundance of flowers. In addition to the water supply, occasional applications of fertiliser are necessary during the growing season in summer. Prune young bottlebrush plants regularly to stimulate flowering and help the Callistemon develop into a compact shrub.

Watering bottlebrush plants

Young plants in particular require generous watering and do not tolerate drought. If the root ball dries out, the plant reacts by producing fewer flowers and sheds its leaves. To avoid this, check the soil moisture daily. If the substrate feels dry in the upper two centimetres, it needs to be watered. It is essential that the planter has a hole in the bottom so that excess water can drain into a saucer. Waterlogging can eventually lead to root rot, which significantly damages the plant. Clay shards at the bottom of the pot further improve water drainage.

How to fertilise bottlebrush

In order for the bottlebrush to keep producing lots of beautiful flowers, fertilise it regularly during the growing season. Our Plantura Liquid Flower Food is excellent for this purpose. It reliably supplies the Callistemon with all the key nutrients. From April to September, fertilise the bottlebrush every one to two weeks with a little liquid fertiliser added to the irrigation water. When using our Plantura Liquid Flower Food, add three to five millilitres of liquid fertiliser per litre of irrigation water.

Plantura Liquid Flower Food
Plantura Liquid Flower Food

Liquid fertiliser with an NK ratio of 3-4, for all flowering plants, promotes healthy plant growth, child & pet friendly

Pruning bottlebrush

Selective pruning lets you maintain the bottlebrush shape and encourage it to bloom extensively. The shoots, at the tips of which the flowers are located, continue to grow in long rods after flowering. Due to the spreading shoots, Callistemon quickly loses its compact shape. Therefore, remove any faded inflorescences. More branches with new flower buds will then form beneath the pruned sections. Bottlebrush can be pruned in spring and late summer. In addition to topiary, always remove damaged or dead shoots. Brown shoots in the middle part of the plant often indicate a lack of light. Here it helps to thin out the plant a bit so that all areas receive sufficient light. If you want to grow the bottlebrush into a bottlebrush tree with a trunk and crown, prune in early spring to avoid disturbing budding and flowering.

Snow covered bottlebrush flower in winter
Bottlebrushes do not tolerate cold and ice at all and must be overwintered indoors [Photo: Konstantinos Livadas/ Shutterstock.com]

Overwintering

The Callistemon is not hardy and must be moved to a frost-proof location in the autumn. Make the winter quarters as bright as possible and ensure temperatures between 5 and 10 °C. Bottlebrushes can also be overwintered indoors in a warmer place. However, the cold stimulus is then missing. The lack of dormancy is reflected in reduced flowering the following year. The substrate must also be kept moist throughout the winter, but do not fertilise the bottlebrush during this period.

Propagating bottlebrushes

Propagation of the bottlebrush can be done in two different ways. Firstly, it can be propagated by seed. The bottlebrush is a pyrophyte, which means that its seed pods can last for years and only burst open and release the seeds when exposed to intense heat. In its natural habitat of Australia, the bottlebrush, like other pyrophytes, follows the strategy of letting its seeds fall on fertile ground during bushfires when its own existence is threatened by the fire.

Therefore, to get to the seeds, you need to heat the fruit capsules of the bottlebrush either over a flame or in the oven. The heat stimulus simultaneously breaks the dormancy of the seeds and makes them germinate. You can then sow them in growing trays filled with substrate. Choose a low-nutrient growing medium, such as our peat-free Plantura Organic Herb & Seedling Compost. Since the bottlebrush is a light germinator, do not cover the delicate seeds at all or only with a very thin layer of substrate. The optimum germination temperature is 15 °C. Always keep the soil moist.

As an alternative to propagation by seed, bottlebrushes can also be propagated by cuttings. To do this, take around ten centimetre-long, ideally flowerless and minimally woody head cuttings from the shoots. Remove the lower leaves, leaving only the top pair of leaves. Cut at an angle with a sharp knife to maximise the area where new roots will form. In addition, rooting powder can be used to stimulate root formation. Place the cuttings in containers filled with potting soil and place them in a bright place without direct sunlight. The optimum temperature for development is 18-20 °C. Always keep the soil moist with a spray bottle. In addition to moistening, plastic hoods are useful for retaining moisture. However, these must be opened or removed for a few minutes every day so that the cuttings are also sufficiently ventilated. You can recognise successful rooting by the fact that new leaves have formed. The seedlings can then be planted in normal soil for the Callistemon and initially placed in a sheltered, sunny to partially-shaded location.

Seeds of the bottlebrush
The seeds of the bottlebrush can be released from their pods by the application of heat [Photo: GABLIYA ALISA/ Shutterstock.com]

Tip: Propagation of the bottlebrush via cuttings usually succeeds better and faster than via seeds. In addition, vegetatively propagated plants are more likely to bloom.

Still wondering if the bottlebrush plant is poisonous? We have good news for you: there are no known toxic effects of the bottlebrush. Nevertheless, it is an ornamental plant that should delight our senses with its beauty and fragrance but is not suitable for consumption.

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