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Poisonous Garden Plants: Iris, Azalea, and Hydrangea

Diana was a member of the Royal Horticultural Society. She & her family all love gardening. She enjoys photographing & painting plants too.

Are You Aware That the Iris, Azalea and Hydrangea Plants Are All Considered to Be Toxic Plants?

Most people know about the very poisonous plants like mistletoe, deadly nightshade and poison ivy, but as a safety precaution, it is important that you should also know about other toxic plants like iris, azalea and hydrangea which might not necessarily kill, but could still poison someone and make them feel very ill.

Paradoxically, many potentially harmful plants, including Irises, are also considered to have healing properties.

Danger Alert! Iris, Azalea and Hydrangea Are All Poisonous Plants

Danger Alert! Iris, Azalea and Hydrangea Are All Poisonous Plants

Poisonous Plant Iris at Chelsea Flower Show

Poisonous Plant Iris at Chelsea Flower Show

1. Poisonous Plant: Iris (Also Known As Flag)

The bulbs of irises are poisonous, possibly only mildly so.

Irises contain the potentially toxic compounds irisin, iridin, or irisine.

Poisonous Parts:

Bulb, leaves, and stem

Symptoms of Poisoning:

The gastrointestinal tract may become affected by the glycoside iridin, causing nausea, vomiting, abdominal pain, diarrhea, and fever. Also, Iris can cause skin irritation or dermatitis.

Medical Uses:

In ancient times Egyptians would grind together salt, small doses of dried iris, mint and pepper, to make a substance for cleaning the teeth. Recent research has shown that the iris really does have beneficial properties and a preparation made from iris is effective in combatting gum disease.

Poisonous Plant Azalea

Poisonous Plant Azalea

2. Poisonous Plant: Azalea

Are azaleas poisonous to humans? Yes they are!

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Read More From Dengarden

Azaleas are a sub-species of the rhododendron family. Azaleas and rhododendrons are ornamental shrubs, which flower in Spring. They are grown for their clusters of spectacularly bright and showy flowers and evergreen foliage.

Unfortunately they have potentially toxic leaves and flowers and even the honey from their flowers can be poisonous.

Poisonous Parts:

Their flowers and leaves contain glycosides, particularly andromedotoxin. This is a volatile resin which, if ingested, burns the mouth, and thus usually discourages potential victims from consuming dangerous quantities of the leaves.

Symptoms of Poisoning:

The human digestive tract is capable of breaking down small doses of andromedotoxins into harmless compounds, so human fatalities from eating these plants are rare. However, victims who consume a lot may suffer from nausea, vomiting, abdominal upset, and low blood pressure.

People who regularly eat affected honey may also suffer similar chronic symptoms.

Treatment:

Detoxification and fluid replacement by doctors.

Poisonous Hydrangea (Botanical Name Hydrangea Macrophylla).  The One Above Is From the Lacecap Species

Poisonous Hydrangea (Botanical Name Hydrangea Macrophylla). The One Above Is From the Lacecap Species

3. Poisonous Plant: Hydrangea (Hydrangea Macrophylla)

Who would have thought that hydrangeas are poisonous plants?

Hydrangea (botanical name: Hydrangea Macrophylla) is a plant that is poisonous to humans, although not usually deadly.

Poisonous Parts:

Leaves, buds, flowers, and bark. The poisonous component is Hydragin.

Symptoms:

stomach pain, nausea, vomiting, sweating, diarrhea, lethargy and, in severe cases, more serious problems like labored breathing, convulsions and coma.

Sensitive people may develop contact dermatitis from handling the plants.

Treatment:

Doctors will try to replace your fluids, help you breathe more easily and administer drugs to bring back your normal heart rhythm.

If You Have Irises, Azaleas or Hydrangeas in Your Garden, Don't Panic

It doesn't follow that if you have them in your garden you will be poisoned--merely that they might affect you

I would just mention that I have all these plants in my garden, and have never experienced any adverse effects, and neither has my cat, or anyone I know.

So what can we conclude from this?

Have I been extra careful?

No--until I started researching, I had no idea that these plants were poisonous. I've been aware since I was a child that plants with white sap, like poinsettias, are poisonous, and I learned the hard way (when my fingers turned black and burnt) that hellebores are poisonous, but these particular beauties--never!

Have I just been lucky?

I will have to answer yes to that. So what do we put my good fortune down to?

All I can say is that I have planted them, touched them, nurtured them and even pruned them without developing any of the symptoms described above. Maybe some people are just more sensitive to noxious substances than I am.....and, of course, I always wash my hands after gardening, and I'm not inclined to lick my fingers or rub my eyes after touching any plants, whether or not I believe they are poisonous. Hopefully, these ingrained habits will stand me in good stead now that Coronavirus is the new enemy.

Has that saved me from being poisoned? Hard to say. But it does seem to be good advice generally.

More Poisonous Plants in This Series

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

Questions & Answers

Question: My granddaughter put a couple of hydrangea flowers in her mouth, but she seems fine. What else should I do?

Answer: Clearly, by the time I received this question, you would probably have discovered whether the hydrangea flowers had any ill effects. My advice to anyone else reading this would be to speak to a pharmacist or doctor as quickly as possible. I am not in a position to give detailed medical advice - I studied law, not medicine!

Question: Can iris leaves give you a rash like poison ivy?

Answer: Iris leaves can give you a rash, but it would depend on your sensitivity, I imagine, as I have certainly never had a problem when handling them. I don't know for sure whether it is similar to a poison ivy rash, but I think it is.

Question: I trimmed my hydrangea back and there were numerous dead stalks sticking up. I reached down to clear the old leaves and the stalks ripped my skin in several places. I developed cellulities and a skin rash. Did the dead hydrangea stalks cause this?

Answer: Hydrangeas can cause skin problems on some people. Certainly, if the skin rash and cellulitis occurred exactly where your skin was ripped, then it does seem likely that hydrangea was the cause. As I said in my article, the poisonous parts are leaves, buds, flowers, and bark.The poisonous component is Hydragin.

According to Healthline : "Cellulitis occurs when certain types of bacteria enter through a cut or crack in the skin. Cellulitis is commonly caused by Staphylococcus and Streptococcus bacteria."

I won't go into more detail here, but the upshot is that you should see your doctor as cellulitis can be serious.

Question: I have a hydrangea planted right outside a large window. I've been ill for a while; I've been shaky and have been having difficulty breathing. Could the bush have poisoned in the air?

Answer: This is debatable.

According to Pollen Library (http://www.pollenlibrary.com/Genus/Hydrangea/),

"Some reports associated hydrangea pollen with hayfever, but allergenic potential of this pollen is not well studied."

According to Teleflora, (https://www.teleflora.com/floral-facts/best-worst-... Hydrangeas are not allergenic.

According to Allergic Living (https://www.allergicliving.com/2013/03/14/plants-t... hydrangeas can cause allergies, because they release pollen into the air rather than relying on insect pollination.

So the penny still seems to be up in the air, but as the air just might be contaminated by pollen, I would say it might be better to remove the bush.

However, I think you might also want to consider whether this is the first year you have had a flowering hydrangea outside your window, or whether you have had it there for years and have never been affected by it previously. Having said this, I am not a doctor, but it seems possible to me that maybe an allergy can develop suddenly, even when you had not previously been allergic to the same substance.

If you do reluctantly decide to remove the plant, remember that it's easy to take cuttings of hydrangea and pot them up. When they have rooted, plant one or more of them in a more distant part of the garden where you won't constantly be breathing in any pollen.

Question: I'm growing irises and companion planting with mandarins to see the effect of water retention in the roots, as well as the potential effect on fruiting. What do you think?

Answer: I have never heard of irises being used as companion plants, but it is probably worth a try, just as an experiment.

Feedback - Do Leave your Comment Below - It's so Nice to Know What People Are Thinking

Trisha on June 23, 2020:

Five years ago while gardening including planting a hydrangea I developed a crazy antibiotic/antifungal resistant infection that started on my wrist following a scratch from a hydrangea branch. I recovered after four days in the hospital. We never fully concluded what happened. Was it bacteria on my skin? Was it mulch or potting soil that got into the scratch? This summer while pruning the same plant I scratched my wrist again! Only this time just a tiny bit. It drew no blood just above my glove. I did consider it but without a skin break I continued my hours of gardening. Two days later the rash is beginning again. At first on my wrist, hours later my knuckles, knees, elbows, seems to be rashing at my joints. Five years ago the infection went sesstemic and bloomed at my limpnodes all over my body. Im convinced this was and is an allergy to hydrangea and not a resistance infection. I love hydrangea but I cant touch them. Its poison ivy for me. This is a broomstick hydrangea BTW.

Diana Grant (author) from United Kingdom on September 01, 2018:

Here is a link to the American Society for the Prevention of Cruelty to Animals, stating two long lists of plants which are or which aren't toxic to cats:

https://www.aspca.org/pet-care/animal-poison-contr...

I hope this helps, as they are far more knowledgeable than I am on this subject.

Pat ragano on August 02, 2018:

Are Christmas cactus and Orchids poisenius to cats.

Julie on July 27, 2018:

Hi there.i only have to wlk past Hydrogena and my airways restrict so suddenly i cannot breath and have to get away quickly . This has happened for years now and as my neighbours garden flourishes with them i even have to cross over incase there is any wind. Strange i know but very true

Diana Grant (author) from United Kingdom on June 05, 2018:

Thanks for the information. Poor doggy - I'm glad she didn't suffer lasting effects.

Lori on May 28, 2018:

Hydrangeas are poisonous to dogs....This morning I threw out a flower arrangement and dropped 2 hydrangea flowers...... My 50# standard poodle picked them up and chewed on them, didn't ingest them.... didn't swallow them.....She became seriously nauseated, started throwing up...... couldn't stop ....