Named for their bottle brush-shaped flowers, this plant can grow as a bottle brush tree or a shrub. Originating in Australia, there are around 50 species of bottle brush plants, each one with a slightly different growth pattern.
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Great attractors of pollinators, the bottle brush tree is a close relative of the paperbark melaleuca. It’s such a close relative, in fact, that all but four varieties have been moved to the melaleuca category!
While commercial nurseries continue to sell most bottlebrush trees as callistemon, most scientists and botanical gardens have made the transition to new names. No worries, though – I’ll make sure you have both to choose from.
No matter if you choose to grow your bottle brush plant as a shrub or as a full bottle brush tree, you’ll enjoy the bright spikes of color! And so will the local butterflies and bees.
Bottle Brush Tree Overview
Types Of Bottle Brush Tree
As I mentioned above, there are around 50 different species of bottle brush trees and some confusion in the naming. I can’t cover them all today, but let’s go over a few of the best-known melaleucas and callistemons!
Callistemon brachyandrus
‘Melaleuca brachyandra’, ‘Callistemon brachyandrus’, ‘Mallee Bottlebrush’, ‘Prickly Bottlebrush’, ‘Scarlet Bottlebrush’
Sharp-tipped leaves are the origin for the “prickly” name for this plant, and it definitely fits. Up to 2″ in length, these pointy leaves require the use of gloves to prune, but the flower stalks more than make up for the trouble.
Those flowers are actually clusters of 7-36 small flowers with extremely long stamens. The stamens are bright scarlet in color with yellowish-green tips, giving them a distinctly dual-colored look.
Visually stunning to look at, this plant can grow from five to thirty feet in height.
Callistemon citrinus
‘Melaleuca citrina’, ‘Callistemon citrinus’, ‘Callistemon lanceolatus’, ‘Common Red Bottlebrush’, ‘Crimson Bottlebrush’, ‘Lemon Bottlebrush’
One of the very first Australian plants to be taken out of the country in the 1770s, the lemon bottlebrush is a popular variety. It produces a profusion of brilliant crimson flower stalks that bloom year-round, washing across the plant in a fiery wave.
Some cultivars produce vivid pink or white stalks as well.
Grown quite often as a tree, melaleuca citrina gets its citrus-related names from the scent of the leaves when crushed. This scent is quite similar to various kinds of citrus leaves and is quite pleasant.
The leaves also tend to produce oils, allowing the fragrance to linger around the plant on warm summer evenings.
This bottle brush tree has a shrubbing habit, tending to stay in the 3-10′ range. It’s often used to create brightly colored hedges. However, it can be trained to full tree growth as well.
Callistemon flavovirens
‘Melaleuca flavovirens’, ‘Callistemon flavovirens’, ‘Green Bottlebrush’
Another bottle brush tree that stays towards the smaller side, the green bottlebrush averages a 3-10′ height.
This plant sends out flowers from May through December in shades which range from a pale green to a cream or white color. Each is tipped with light yellow, giving that multilayered coloration that bottlebrush plants are known for.
New leaf growth is silvery but darkens to a medium green tone against the dark, woody bark. Unlike some of the other bottle brush varieties, this plant produces egg-shaped leaves with the narrower part of the egg towards the stem.
Callistemon glaucus
‘Melaleuca glauca’, ‘Callistemon glaucus’, ‘Callistemon speciosus’, ‘Albany Bottlebrush’
Widely grown as an ornamental, callistemon glaucus tends to stay in the shrubby growth pattern of up to 10′ in height. Its leaves tend towards a lighter green with a bluish tinge to them and are long and slender with a slightly ovoid shape.
The flower stalks for the Albany bottlebrush tend to stay in the bright red or deep red-pink range tipped with tiny pale yellow specks.
Callistemon linearis
‘Melaleuca linearis’, ‘Callistemon linearis’, ‘Callistemon pinifolius’, ‘Callistemon rigidus’, ‘Narrow-Leaved Bottlebrush’, ‘Pine-Leaved Bottlebrush’, ‘Stiff Bottlebrush’
As you can tell, this plant has had quite a number of botanical names over time. In part, that’s due to the confusion of particular cultivar names with the botanical name.
The base species has leaves that are linear in shape and about a half-inch wide, where the other cultivars vary in their leaf shapes slightly.
Producing vibrant red spikes of color, the narrow-leaved bottlebrush is a good choice for people in damper or swampier locales. It is widely cultivated but is most often seen in roadside plantings rather than garden environments.
Callistemon nervosus
‘Melaleuca nervosa’, ‘Callistemon nervosus’, ‘Callistemon nervosum’, ‘Fibrebark’, ‘Paperbark’
Fibrous, papery bark from this plant was used widely by aboriginal Australians for carrying containers or padding. The oil-producing leaves were used as a decongestant but also used in a similar way as the related tea tree plant (Melaleuca alternifolia).
With blooms in either a creamy white or a rich, dark red, fibrebark is a popular bottle brush tree to grow. It’s a distinctly tree-type plant, growing from seven to fifty feet in height.
The layered bark makes an interesting element in landscaping, and the blooms appear from April to September.
Callistemon phoeniceus
‘Melaleuca phoenicea’, ‘Callistemon phoeniceus’, ‘Scarlet Bottlebrush’, ‘Lesser Bottlebrush’, ‘Tubada’
With a height that can soar to up to 20 feet, this bottle brush tree can be grown as either a tree or a shrub. The lesser bottlebrush is capable of growing in a number of soil types although it prefers sandier soil, and tends to transition well to unusual climates.
Spires of pinkish-red or purplish-red flowers rest above lateral blue-green leaves and rough bark. Flowering tends to be heaviest from October through January in its Australian natural habitat but can happen at other times of the year.
Callistemon polandii
‘Melaleuca polandii’, ‘Callistemon polandii’, ‘Gold-Tipped Bottlebrush’
A hardy shrub that can grow to 10′, the gold-tipped bottlebrush is widely grown in warm coastal areas. It’s one of the varieties that has transitioned extremely well to California growing, particularly in southern or central areas of the state.
This bottle brush plant is widely used as a hedge or shrub plant, as it tends to fill out extremely well. However, it’s known to damage wastewater pipes, so avoid planting this near buried water or sewer pipes.
Callistemon salignus
‘Melaleuca salicina’, ‘Callistemon salignus’, ‘White Bottlebrush’, ‘Willow Bottlebrush’
Popularly seen as a streetside tree or shade tree in a park, the white bottle brush tree can grow to heights of up to 50 feet. Its papery bark and white flowers are a popular landscape addition.
Cultivated forms can have pink or red flower stalks as well, but it’s known for its white blooms.
Its leaves have a resemblance to those of some willow species, spawning one of its common names and the reference to salix in the botanical name. The creamy white flowers tend to be a food source and draw birds of multiple types.
Callistemon subulatus
‘Melaleuca subulata’, ‘Callistemon subulatus’
For people in more northern reaches of California and up the west coast of the United States, considering callistemon subulatus is one of their best bets. This bottle brush shrub grows 3-7′ tall and makes an excellent hedge plant, producing flowers through most of the summer months.
Hardy in many environments, this plant can tolerate cooler temperatures or extremely hot ones, provided that it has some shade. It also does fairly well with sea air, and is a popular plant in and around San Francisco.
Callistemon viminalis
‘Melaleuca viminalis’, ‘Callistemon viminalis’, ‘Weeping Bottlebrush’, ‘Creek Bottlebrush’
Last on the list, but definitely not least, is the weeping bottle brush. Possibly the most cultivated of the bottle brush plants in garden settings, this is absolutely the most popular variety on today’s list!
Raised either as a shrub or as a multi-trunked tree that can reach heights of 30 feet, the weeping bottlebrush provides food for nectar-consuming wildlife.
Its dense root system is used to reinforce riverbanks, as the roots mat together and help to prevent erosion.
Callistemon viminalis is not frost-hardy and has issues with salt spray. However, it can be grown in most environments if protected from cold or sea air. This plant has become popular around the world for its brilliant red profusion of flowers.
Bottle Brush Tree Care
Once established, care is super-simple: water it when the soil starts to dry out and give it some fertilizer at regular intervals. Young plants require a little more preparation, though.
Read on to find out the best way to prepare your bed and care for your bottle brush tree!
Light
Before you plant your bottle brush plant, it’s important to be sure your sun conditions are going to be right.
First, consider your bottle brush tree species. The vast majority of them prefer full sun, but there are a few of the shrubbing types which can tolerate partial shade.
Second, make sure that the sun will reach that spot in the winter. A south-facing placement usually ensures you should have adequate sunlight for most callistemons all year.
As bottle brush plants do well in zones 9-11 normally, they tend to have good resistance to too much heat. They won’t like the cold, however. Some varieties can take low temperatures, but they are not able to handle repeated frost conditions.
If you live in a location where you get snow or extremely cold conditions during the winter, you should keep your bottle brush tree in a shrubbery-type growth type and plant it in a container. That way, you can optimize placement for light, and it can be brought indoors with a grow light for the winter months. The best containers out there, Air Pots, are stocked in our online store!
Older bottle brush trees that have gained significant growth can tolerate cold weather better than those which are young.
Water
The average bottle brush is going to prefer regular watering, but it won’t necessarily require daily watering as these plants tend to be somewhat drought-resistant.
Depending on its specific species, age or size, watering requirements vary widely. However, a good rule of thumb during the first year or two is to check the top four inches of soil at the base of the plant. If it is damp, you’re giving it enough water. If it’s powdery and dry, it needs watering.
To develop a good root system, I recommend slow, deep watering patterns. Using a drip system or soaker hose will provide these conditions and help encourage the root mass to expand as necessary.
Established plants that are more than two years old are much more drought-resistant than younger plants. These have had plenty of time to establish a good root system. Water older bottle brush trees during prolonged dry periods or when trying to stimulate flowering.
You’re welcome to water more often, as long as the soil drains really well. However, be careful not to overwater!
Bottle brush trees can withstand short periods of flooding, but try to avoid standing water once floodwaters recede.
Soil
Bottle brush trees grow well in a wide variety of soil conditions. In the wild, they often grow along creek beds or in sandier soils, but some species do extremely well in clay as well. Some species have extensive matting root systems that can help prevent erosion, even with sandier soil.
Still, one thing which should always be avoided is highly alkaline soil.
Too much alkalinity will cause bottle brush trees to suffer yellowing of their leaves from chlorophyll loss. If leaves remain yellow for too long, the plant will die off as it can’t process sunlight properly.
For overall best results, go for a pH range between 5.5 and 7. Work in some compost to add nutrients, and perlite to slightly loosen clay-type soils. If you have sandier soil naturally, skip the perlite and simply work in compost.
Your overall goal is to have soil which the roots can easily permeate and which remains damp, but not wet. Application of a few inches of mulch around the base of your plant will help keep the soil moist.
Fertilizer
I like to use a balanced, slow-release fertilizer for my bottle brush shrub. Applied evenly at the beginning of the spring, summer, and fall, an 8-8-8 slow-release fertilizer will encourage steady growth and flowering.
You don’t need to fertilize in the winter, as the plant simply won’t need added nutrition then.
A little extra phosphorous can help stimulate flower production in the right season and at the right time. The problem is that it needs to be applied a few weeks before normal flowering begins.
If you’re not sure when flowering should happen for your plant, it’s best to stick with a balanced fertilizer.
Propagation From Cuttings
It’s extremely easy to start your bottle brush tree from either seed or cuttings.
For cuttings, you want to take 6-inch cuttings from semi-mature wood. The best time to do this is during the summer. Use sterilized pruners to take the cutting.
Once you have your cutting, pinch off any lower leaves on the stem and any flower buds. Dip your cutting into a rooting hormone powder and then put it into your growing medium. You can use perlite, potting soil, or a number of other starters as growing medium.
Make sure the medium is damp, and then cover the cutting with a plastic bag to help keep moisture inside. You can base-water by setting your potted cutting into a tray of water if necessary but avoid overwatering.
Wait for the cutting to take root, which should happen within 9-10 weeks, then remove the bag and acclimate your plant to the lower humidity before repotting.
Propagation From Seed
If you have a seed, it’s simple enough to plant, but it will take a bit longer for your plant to become hardened to the weather. To give it the best chance, sow your seed during the springtime in a balanced potting mix.
As bottle brush plant seeds are extremely tiny, they will resemble dust. This means you’re likely to sow them rather heavily, but that’s okay. Thin down excess plants and keep the strongest specimens as they appear. Try to leave a few inches of space between plants.
Once they’re at least 6-8 inches in size, you can gently separate them and repot them.
Keep in mind that if you are growing different varieties of bottlebrush plants, they hybridize easily. The best way to keep the same features as the parent plant is to take cuttings.
If you’re only growing one variety, the seeds should produce true clones of their parent plant in most cases.
Transplanting
Transplanting your bottle brush requires some preparation of the soil. Read the “soil” segment above for more information.
For older bottlebrush trees, you will want to prepare a hole based on the size of the current plant roots. If the roots have a foot and a half spread, for instance, you want to prepare a hole that’s at least two feet deep and three feet across at the topmost point.
Preparing the soil in advance loosens it and makes it easier for the roots to spread out in. As much of the root mass will be a tangled mat near the surface, you need to ensure that there’s plenty of room for those roots to adapt to!
Young plants need a smaller prepared space. A good rule of thumb is to double the root mass in width, and at least 1.5 times the root mass deep. This gives plenty of good aeration.
Potted bottle brush shrubs should be given 3-6 extra inches of space in their pot when transplanting to a new pot.
Pruning
There are two types of pruning that are commonly done for bottlebrush shrubs or trees: tip pruning, or flower pruning.
Tip pruning should be done when the new growth is still extremely young, and before it’s had the chance for the stem to harden in any way.
As flowers will grow from these tips, you may sacrifice some flowers if you prune the stems too late. However, this will help you shape the plant if necessary.
Flower pruning is done just as the flowers are beginning to fade. Neatly snip off the flower just behind the lowest set of blossoms, leaving as much stem intact as you can. This may spur additional flower growth from the same stem.
You can prune to train your bottle brush plant to a specific growth pattern. Bottle brush trees also work well for the traditional practice of espalier or training against a wall or building.
Collecting Seeds
If you want to gather seed from your bottlebrush tree, be sure to leave the flowers intact even after they’ve faded. That flower stalk is where the seed pods grow.
Pollinated flower stalks will form seed heads filled with multiple seed pods. Initially, these will be greenish, but over time they will dry to a dark, hardened brown.
As they start reaching the brown and hardened stage, place a paper bag over the top and rubber band it in place beneath the seedhead securely. Wait for a bit longer, and then cut off the stem below the seedhead and leave it to completely dry out.
The seed pods will open on their own as long as they’re kept in a warm, dry place, and a good shake will release the seed into the paper bag.
The majority of your problems will arise from overwatering. But there are a few pests which can attack your bottle brush. Let’s go through the possible issues that might arise and how to deal with them.
Growing Problems
Winter’s chill can cause leaf browning on your bottle brush tree. But do not panic! As long as the branches themselves are not dead, it can recover.
If you’ve had a sudden cold snap, consider wrapping plastic or burlap around your plants to keep them a little warmer.
Be sure to leave ventilation at the top and underside of the plant so you don’t develop powdery mildew or leaf spot. Remove it as soon as the weather warms back up.
Pests
There are a few pests that attack bottle brush: sawfly larvae, scale, and the web moth (also referred to as the webbing caterpillar).
The sawfly itself will not harm your plants, but their larvae assuredly will. These sawfly larvae cause skeletonization of leaves and defoliation.
You can eliminate the larvae with a number of products including neem oil or a more potent azadirachtin spray like AzaMax. Also consider spinosad sprays like Monterey Garden Insect Spray, or even dusting the plant with diatomaceous earth.
Scale insects are a bit more irritating, as they can be hard to spot hidden on the underside of leaves. These cause pale trails to form through your bottle brush leaves.
For small infestations, you can carefully scrape the scale off, or blast it off with hard sprays of water. Larger infestations respond well to the use of neem oil or AzaMax.
Finally, the most destructive pest to bottle brush shrubs is the web moth, also known as the webbing caterpillar. These pests will attack younger foliage, webbing it together to form a cocoon. They can defoliate plants quickly, and one of their favorite targets is the bottle brush.
If you see any branches or leaves pulled together to form a cocoon, or dust that looks like sawdust near a web-coated section of branch, remove it immediately and dispose of it. This should remove the web moth larvae.
While I don’t know if it’s been tested against webbing caterpillars, bacillus thurigiensis (also known as BT) should help destroy these larvae. It’s certainly worth the effort!
Use a product such as Monterey BT if you wish to see if the bacillus will deal with your caterpillar problem, being sure to thoroughly soak through any cocoons to hit the webbing caterpillars within.
I really dislike suggesting inorganic methods to combat a pest. However, if you do not trim off visible cocoons and the BT doesn’t work, you may have to resort to the use of a carbaryl insecticide such as Sevin. This is known to be extremely effective against web moth larvae.
Diseases
Root rot can affect bottle brush trees if the soil is consistently too wet. This soggy soil promotes the growth of fungi that cause the root rot. It can cause yellowing of leaves, discoloration of the trunk, dying back of branches, and can lead to plant death.
To avoid this, water your bottle brush plant only when it needs it, and water slowly but deeply to allow water to penetrate the soil and drain off well. If necessary, apply a copper-based fungicide such as Bonide Copper Fungicide as a soil drench to try to kill off the fungal growth.
Another disease, stem disease, develops also from overwatering. Stem disease is a bacterial issue that also enters the roots but travels to the branches. It causes stunted, thin branch growth and can slowly kill your plant.
Ensuring your plant has full sun will help water evaporate from the soil more quickly, but the easiest way to avoid this is to simply not overwater. Treatment is withholding water until the soil is dry, then only water enough to just barely dampen the soil.
Limit the plant’s exposure to water until it recovers from the bacterial infection, and prune damaged branches. Be sure to sterilize your pruners to avoid cross-contamination.
Powdery mildew is caused by dampness on leaves where yet another fungus can develop. This one, at least, is relatively easy to treat! Spray all plant surfaces, both tops and bottoms, with neem oil. Retreat every few days until the powdery mildew is gone.
Leaf spot is the final fungal growth that can become a problem. While a few spotted leaves won’t harm anything, if the fungal growth spreads throughout the plant’s leaves it can cause plant death. Avoid watering the foliage, which is where the fungi develop if it remains wet for too long. Ensure the plant has plenty of airflow around it to keep leaves dry.
