Are Bonsai Trees Poisonous To Humans? The Complete List

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Bonsai trees are made up of hundreds of different varieties, species, and breeds – heck it’s one of the reasons why so many of us (myself included) love the hobby of miniature trees! Like anything based in nature, certain species have adverse effects on humans and animals alike and so understanding if bonsai trees are poisonous to humans is incredibly important. 

Certain plant species used for bonsai such as Cotoneaster, Elder,  and Eucalyptus have properties that can be poisonous to humans ranging from rashes and gastrointestinal problems to some even being fatal. Most bonsai species will try to defend themselves, which can lead to them being poisonous. 

It’s important, then, for beginners to handle them with care. 

So which species are the most poisonous to people? And what exactly do these poisonous plants cause? Keep reading to find out more!

Just a quick heads up, over the past three years of running Plantpaladin, hundreds of people have asked for product recommendations. As such, You can find my favorite indoor bonsai tree here (link takes you to Bonsaiboy), my favorite outdoor bonsai tree (link takes you to Bonsaiboy), or have a look at all the products I recommend here. 

Are bonsai trees poisonous to humans? 

Plants and trees have been around for millions of years, with a lot of people believing that they have evolved alongside people and other animal species (heck, it’s one of the reasons we refer to them as flora and fauna) 

As such, a lot of plant species have had to come up with self-defense mechanisms to survive. 

When people first started bonsai in Japan in the 12th century, a lot of the plants that were used had mild or very serious side effects. 

Some species used In bonsai, if not handled correctly, are toxic. 

So which plant species used for bonsai are the most poisonous? To help explain more I’ve put together a table below with just some plants that have been known to be poisonous for the most common species used in bonsai: 

Plant Name	Scientific name	Why is it poisonous to humans
Firethorn	Pyracantha	Berries can cause gastrointestinal issues if ingested
Ficus	Ficus Benjamina	Mild rashes, gastrointestinal issues if non-edible parts are ingested
Elm	Ulmus	Potential for Ascomycetes living in plant
Elder	Sambucus	The bark contains oxide crystals, leaves fruit and seeds contain cyanoglycoside sambunigrin, known to get fungal infections like white powder
Ecalyptus	Eucalyptus globulus	Untreated oil of more than 3,5 ml can be fatal, cause severe dizziness fatigue, and gastrointestinal issues.
Box	Buxes	Leaves cause rashes if touched, leaves also produce alkaloid buxine which has been linked to nausea vomiting, and even paralysis in some very serious cases.

Let’s explore these plants and many other of the more popular breeds used in bonsai in more detail as to why they are poisonous

Are firethorn bonsais poisonous to humans? 

Firethorn species are one of the most common species used in bonsai and are very popular because of their bright red leaves.  

Firethorn bonsais or more specifically the seeds of the berries the plant produces can be poisonous if not treated properly, and ingested raw, which can lead to gastrointestinal issues. This is because they contain cyanogenic glycosides. To treat ensure you wash these seeds thoroughly and crush them

Are forsythia bonsais poisonous to humans? 

Forsythia bonsai are also very popular for bonsai use especially in Asian countries such as China, which has been using the plant for hundreds of years in Chinese medicine. 

Forsythia plants are not a poisonous species of plant to humans due to their non-toxic nature and so can be used in bonsai without any real issue for bonsai. That being said it is not advisable to eat any part of the plant that is not edible. 

Are box tree bonsais poisonous to humans? 

Box plants ( Buxus) are one of the most common species of plants used for bonsai due to the look they and the shapely nature that the trees have. 

Box trees whilst nice to look at are incredibly toxic and poisonous when handled, so need to be treated with great care if used for bonsai. Box plant leaves produce alkaloid buxine which can cause vomiting and nausea in people and animals. 

Boxtree leaves can also be toxic cause skin irritability and rashes. 

Are Ecalyptus bonsais poisonous to humans? 

Eucalyptus plants and trees are super popular due to the oil they produce which has been found to have several health benefits. 

Bonsais made from raw eucalyptus plants and trees can be incredibly toxic and poisonous. If the oil the tree produces has not been treated, ingesting a small amount like 3.5ml can be fatal. Eucalyptus poisoning will include stomach pain, a burning sensation, fatigue, dizziness, nausea vomiting, and diarrhea. 

I would definitely avoid this breed if you are a beginner and just getting started with bonsai as it requires a lot of care and practice to become good at. 

Are cherry bonsais poisonous to humans? 

Using cherry trees of bonsai, regardless of their species are one of the most common species used. 

With Bonsai starting in japan and ornamental cherry blossom trees looking as stunning as they do it is no surprise that these are the types of plants that would be used primarily in bonsai. 

Cherry bonsais are toxic and poisonous to humans as wild cherry twigs and leaves can release prunasin, a type of cyanide that when ingested can be fatal. This typically happens when the tree is under stress or the leaves start to wilt so handle with care. 

Are elm bonsais poisonous to humans? 

Go to any bonsai garden center, heck goes to any supermarket, and most likely the type of bonsai you will likely find will be Chinese and Japanese elms plants 0 as such they are often used a lot for beginners. 

Elm bonsai species are not toxic or poisonous to humans and can be handled with relative ease. Elm species however may contain Ascomycetes which is a pathogen that produces spores that can be toxic as well as can destroy your plant. 

It is important then, that you create a regular check-up on your bonsai once per week to ensure you are preventing it as best as possible from outbreaks such as this. To find out more about how to do this, check out my post on removing scale which has a fantastic weekly check-up you can follow. 

Are elder tree bonsais poisonous to humans? 

Like elms trees, elder trees are also one of the most commonly used species in bonsai with some species blooming white flowers which can be particularly stunning in the summer months, 

Elder trees can be poisonous species of tree to use for bonsai for humans. Elder tree bark contains calcium oxalate crystals (which have been linked to kidney stones). The leaves and fruit also contain cyanoglycoside sambunigrin. Elder trees also suffer from white powder or mold infestations which can cause respiratory issues. 

If your bonsai is currently suffering from white powder you might want to check out my blog post here which covers exactly how to resolve this issue. 

“As bonsai is made up of thousands of differnt species, a lot of the plants we use can be posiniouse via touch and consumption if not treated properly”

The complete list of poisonous bonsai species

As there are thousands (if not millions) of species of bonsai, all of which have varying degrees of toxicity to humans, it would be difficult to compile a list – however, I’ve done my best to list below all the species that are the most toxic in the list below: 

Species	Why is it poisonous to humans
Acacia	releasing ethylene gas from the pores
Apple	Seeds are mildly poisonous
Alder Buckthorn	Toxic if ingested due to emodin
Azalea	Toxins can cause vomiting diarrhea and heart palpitations
Beech	Nuts can be toxic if eaten in a high dose
Birch	Not suitable for people with pollen issues
Chestnut	Twigs can release prunasin
Cotoneaster	Contains cyanogenic glycosides which can affect the heart kidney and brains particularly in children.
Douglas Fir	Ingesting needles can cause gastrointestinal discomfort
Dogwood	Regular infestations of insects
Dieffenbachia	Can cause redness of the skin
Ficus	White sap cause itchy eyes, coughing, and wheezing
Ginkgo biloba	Poisonous seeds
Guelder rose	All parts of the tree are poisonous to humans causing vomiting and diarrhea
Grevillea robusta	Contact dermatitis
Holly	Berries can cause intestinal discomfort
Idesia	Fruit can be poisonous if not treated properly.
Incensed Cedar	Contains oils that can be toxic in large portions
Jacaranda	Pollen can cause irritation and rashes
Jasmine	Sap can cause rashes, contains gelsemine  which can be toxic if consumes
Juniper	Oils in the plant can be toxic if ingested causing vomiting
Kentucky coffee	Toxic seeds
Laburnum	Contains cytosine which can cause diarrhea, vomiting convulsions, and even coma
Manchineel	The sap is incredibly dangerous causing blistering of the skin and the fruit can cause gastrointestinal issues
Mock orange	Seeds and flowers can cause rashes and nausea
Myrtle	Oils can produce headaches
Nandina	Posniuse if consumed and can be fatal
Neea	Can cause rashes, itches, and dermatitis
Oak	Can cause stomach upset if the leaves are eaten
Oleander	Extremely poisonous if ingested, causing vomiting diarrhea, and headaches
Olive	Pollen issues for those suffering from hay fever
Plum	Seeds and pips are toxic and should be discarded
Podocarpus	Male species release pollen in the summer that can cause infections
Privet­	Some species can cause headaches and vomiting if ingested
Quince	Seeds can react to stomach acid creating cyanide
Rhododendron	If ingested can cause diarrhea, vomiting, and impaired vision
Rosary Pea	Seeds poisonous if ingested
Rowan	Berries can cause eye problems and rashes if ingested
Snowberry	Causes vomiting, headaches, and delirium if berries are eaten
Spindle tree	Poison fruits
Spurges	Skin irritation
Titoki	Bark leaves and fruit have cyanide producing toxins in their bark leaves and fruit
Umbrella tree	Consuming the leaves can cause mouth numbness, vomiting, and abdominal pain
Viburnum	Berries are toxic if consumed
Virginia creeper	Ingesting any part in small amounts can be lethal
White cedar	Can cause skin irritation and Asthma
Willow	Contains toxins in the bark that can be toxic if ingested
Wisteria	Toxic if ingested causing fainting, vomiting, and nausea
Xanthorhiza	Nausea and can cause urinary tract infections
Yew	Incredibly poisonous, if ingested can cause low blood counts, muscle and joint pain, skin rashes, and asthma

Why are some plant species poisonous? 

So now we know exactly what bonsai plant species are more poisonous we have to ask ourselves why? 

Some plant species are poisonous as they cannot move around or hide from predators. As such the only natural defense mechanism they have to protect themselves are things like toxic fruit, chemicals, and pheromones to stop pests and animals from eating them 

For a full list of poisonous plants, check out wigans local authority list which has a fully comprehensive list here. 

Most common illnesses caused by bonsai species 

So what exactly are some of the side effects caused by bonsai species., After all, according to some studies, plant poisons have thousands of different types of illnesses they can cause. 

The main illnesses caused by some bonsai species are vomiting, headaches, gastrointestinal discomfort, skin rashes, and itches. More severe illnesses and side effects can be heart palpitations, dizziness, fatigue memory loss, and in some extrema cases, coma and death. 

What is the most poisonous species of plant used in bonsai?

Whilst there are several species of the plant out there that are incredibly deadly such as Snakeroot, Castor Bean, and Rosary Pea what are the most dangerous species of plant most commonly used in bonsai. 

Eucalyptus plants, although used very commonly for bonsai, is arguably one of the most dangerous species to use. This is because of the oil, which If left untreated can be fatal if consumed. This can take as little as 3.5 ml so ensure if you use this plant, handle it with extreme care. 

How do the poisons from bonsais pass on to humans?

So now that we know that some species of plant can have severe side effects on people how can we ensure we minimize our risk of suffering these side effects? 

The main way in which toxins from bonsais are passed on from plants to humans is through digestion – with most plant species being toxic when their leaves, fruit, bark, or seeds are eaten. Some species like ivy can pass on their toxins via touch. 

Some plant species used for bonsai also pass on their toxins via the fertilization process with pollen spores caused symptoms that are typical with pollen allergies. 

So simply put the best way to avoid any of these side effects is to: 

• Keep bonsais out of the reach of children who may ingest these plants unknowingly 
• Ensure you handle bonsais with care when pruning, wearing gloves for any skin rashes
• If handling seeds be extra careful with the majority of seeds for these plants proving to be toxic

 

My top picks for the gear you will need!

So like I mentioned earlier, over the past three years of running PlantPaladin, hundreds of people have asked me for my recommendations on the best bonsai gear on the market. 

Having spent thousands of dollars on bonsai items these past few years and tested at least 100 bonsai-specific products, I’ve listed my favorite products below – All of which I highly recommend and think you can get great value. 

They can purchase directly by clicking the link to take them to Amazon. 

Bonsai Tool Set: One of the significant challenges I’ve had is finding a toolset that was not only durable but didn’t break the bank. SOLIGT has recently developed a fantastic bonsai tool set that covers all the tools you need to trim, prune, and repot your trees. – You can grab it here. 

Complete Bonsai Set: Many of you will want to grow your bonsai trees entirely from scratch, but finding the varicose seeds, pots, and other items in one place can be challenging. Leaves and Sole then have created a complete bonsai set that I’ve personally used that ticks all the boxes. You can grab it here. 

Bonsai wire: The number of times I’ve run out of wire for my bonsai or purchased cheap bonsai wire that doesn’t do the job is embarrassing for me to admit. After a lot of trial and error, I found that using Hotop’s aluminum bonsai wire is one of the best options on the market. This can easily be used for both indoor and outdoor bonsai. You can grab it here.