Poisonous Plants for Pets: Houseplants, Garden and Farm

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Quick Facts

Most houseplants only cause mouth burning. A few kill: lilies destroy a cat's kidneys, sago palm and oleander destroy the liver and the heart, and ragwort destroys a horse's liver cumulatively. Roses, spider plants and Boston ferns are entirely safe. Know the six that matter, then relax.

Caro and I are not vets, and this is personal research rather than veterinary advice. It is research I do anyway, because I sit in other people's houses and I would rather know which of their plants could hurt the animal I am responsible for. We have had a lily in a house with a cat and moved it out of reach within the first hour, not because anything had happened, but because it only takes once.

You never quite finish learning this. On our current sit we are almost five months in, and the cat still surprises us. We clean the kitchen every day, everything goes away, and it still finds something. This morning we woke to a jar of coconut oil on the floor, cracked, with the contents across the terracotta tiles and glass in the oil. Not many shards, but one is enough. So we are doing what you do: watching the cat, checking it is behaving normally, and knowing exactly who we would ring if it was not + we already notified the owners so they know the situation.

That is the entire method, and it applies to plants as much as to glass. Know what matters, keep it out of reach, and know who to call. The whole process of sitting, from first application to handover, is in our book Travel More for Less.

For most of Europe we point sitters at TrustedHouseSitters first. If you have already found something in a pet's mouth, what to do when a pet eats something dangerous is the page you want, and it is the practical companion to this one.

The Plants That Actually Kill

Start with the small number that genuinely end animals, because everything after this is reassurance by comparison. There are six worth memorising, and if you learn nothing else from this page, learn these.

Lilies

True lilies are fatal to cats and harmless to dogs. That split is the single most useful fact on this page. Lilium species, which includes Easter lilies, Asiatic lilies and tiger lilies, cause acute kidney failure in cats. The ASPCA lists the toxic principle as unknown, which is worth knowing because it means there is no safe amount. A cat that walks through pollen and then grooms itself is at risk. If you are sitting a cat and the house has lilies, move them somewhere the cat cannot reach, and if you suspect any contact, ring a vet immediately rather than watching.

Sago palm

This is the one that surprises people, because it is an ordinary-looking pot plant and it is genuinely dangerous. Cycasin causes liver failure and a bleeding disorder, and the ASPCA lists it as toxic to dogs, cats and horses. Every part is toxic and the seeds are worst. The survival rate is poor even with treatment, which is why it belongs at the top of the list rather than buried in a table.

Oleander, yew and foxglove

These three share a mechanism: they attack the heart. Oleander contains cardiac glycosides and the ASPCA lists the clinical signs as drooling, abdominal pain, diarrhoea, colic, depression and death. Yew contains taxine and causes sudden death from acute cardiac failure, sometimes with almost no warning. Foxglove contains the same cardiac glycosides as the heart medication digoxin, and causes arrhythmias and cardiac failure. Oleander is a Mediterranean ornamental, yew is a hedging plant in half the gardens in Britain, and foxglove grows wild in woodland and is planted in cottage gardens. All three are worth knowing by sight.

Autumn crocus

Not the spring crocus, which is a different plant and far less dangerous. Autumn crocus contains colchicine and causes bloody vomiting, diarrhoea, shock, multi-organ damage and bone marrow suppression. It flowers in autumn when the rest of the garden is finishing, which is exactly when nobody is looking at the flower beds.

Ragwort

The farm one, and the reason it is here rather than in a footnote. Ragwort contains pyrrolizidine alkaloids and causes cumulative liver failure, and the damage is irreversible once symptoms appear. The reason it kills so many horses is the detail that surprises people: it stays toxic when dried, and drying removes the bitter taste. So it gets eaten in hay, where the horse cannot taste it and cannot avoid it. If you are sitting a smallholding, this is the plant to walk the field for.

What Is Dangerous in the House

You are living in someone else's home, surrounded by houseplants you did not choose and probably cannot name. Good news first: the great majority of common houseplants cause mouth burning and drooling rather than anything worse.

The mechanism behind most of them is the same. Peace lilies, pothos, philodendrons, dieffenbachia, caladium, calla lilies, Chinese evergreen, flamingo flower, nephthytis and schefflera all contain insoluble calcium oxalate crystals. Chewing releases them and they physically irritate the mouth, tongue and lips. The ASPCA describes oral irritation, intense burning, excessive drooling, vomiting and difficulty swallowing. It is genuinely unpleasant and genuinely rarely fatal.

The dangerous houseplants are the outliers rather than the crowd: lilies for cats, sago palm for everyone, and a handful of others where a large enough dose causes real harm. Kalanchoe causes abnormal heart rhythm. Cyclamen tubers can cause heart problems, seizures and death. Amaryllis bulbs in quantity can do the same. Daffodil bulbs cause convulsions in large ingestions. Rhododendron and azalea contain grayanotoxins, and the ASPCA notes that a few leaves can cause serious problems.

If you want the practical version: a house full of plants covers the caretaking side, a plant that dies in a heatwave covers the other kind of plant failure entirely, and the rule for a pet household is simple. Anything high up stays high up, and anything within reach gets moved before the animal finds it.

What Is Dangerous in the Garden

Outside, the stakes go up. Garden plants include most of the genuinely lethal species on this page, and a garden is harder to police than a windowsill.

The pattern is worth understanding rather than memorising plant by plant. Bulbs are usually worse than flowers. Tulip bulbs contain tulipalin, daffodil bulbs contain lycorine, and the ASPCA is explicit that the highest concentration sits in the bulb. Foliage is often worse than fruit. Tomato leaves and stems contain solanine and are toxic, while the ripe tomato itself is harmless. Rhubarb leaves are dangerous and the stalks are not. Potato foliage, sprouts and green parts contain solanine.

The one that catches people out is hydrangea, which contains a cyanogenic glycoside. Cyanide sounds catastrophic and the ASPCA is reassuring about it: cyanide intoxication from hydrangea is rare, and the usual outcome is vomiting, depression and diarrhoea. Compare that with oleander or yew, where the outcome is death. This is why a flat list of "toxic plants" is less useful than a list sorted by what actually happens.

Compost, garden waste and fallen prunings deserve a mention too. A dog will eat a dropped yew clipping that has been lying on the lawn for a week, and the toxin does not evaporate. If you are sitting somewhere with a gardener or a mower coming, ask them not to leave clippings where the animals go.

What Is Dangerous on a Farm or Smallholding

Farm sits are a different order of problem, because the animals are larger and the plants are in fields rather than pots. If you take one of these, our farm animal guide covers the practical side, and the birds are covered further down.

Ragwort is the headline, and if you only do one thing on a smallholding, walk the pasture and pull it. It is a yellow-flowered weed, it is common in the UK and Ireland, and the cumulative liver damage it causes is the single biggest plant threat to horses. Wear gloves, because it is also a skin irritant, and dispose of it rather than leaving it to dry.

Beyond ragwort, horses face yew, which is often planted in churchyards and gardens rather than fields, and sycamore seeds, which cause atypical myopathy in horses and are documented mainly in the equine literature. Oak is a slower risk: acorns and young leaves in quantity cause gastrointestinal and kidney damage, and the MSD Veterinary Manual notes that poisoning requires a diet that is a substantial proportion of oak over time. Cattle and sheep add bracken and a long list of others.

For poultry, the picture is narrower and the sources are thinner, which is worth saying honestly. Chickens are more tolerant of many plant toxins than mammals are, and the more common poultry risk is not a plant at all but the wrong kitchen scraps. We cover the practical side in the chicken and duck guide, including a section on heat and electrolytes that came out of our own Portugal sit.

The Big Table

Every plant below is sourced from the ASPCA Toxic and Non-Toxic Plants database, which covers dogs, cats and horses. The warning symbol marks the ones that can be fatal. Species are given as the ASPCA records them, and a plant that is toxic to dogs is not automatically toxic to cats, which is exactly why this column matters.

A note on reading any plant list, including this one. Veterinary sources disagree at the margins, and no database is exhaustive. The ASPCA is the standard reference for dogs, cats and horses, and it is the one to check when you meet a plant that is not here.

What Is Actually Safe

Now the part that saves you unnecessary worry, and it covers the plant people ask about more than any other.

Roses are non-toxic to dogs, cats and horses. The ASPCA lists Rosa species as non-toxic with no toxic principle at all. If a homeowner has roses and a dog, there is nothing to do. The real risk with roses is the thorns, which can injure a mouth or a paw, and any pesticide or fertiliser that has been applied to them, which is a different problem entirely and worth asking about.

The safe list is longer than most people expect, and it is worth putting on the fridge if you sit often. Spider plants, Boston ferns, African violets, prayer plants, Christmas cactus, areca palms, kentia palms, majesty palms and cast iron plants are all listed as non-toxic. In the garden, sunflowers, marigolds, nasturtiums, petunias, impatiens, zinnias, cornflowers, lilac, fuchsia, honeysuckle, forsythia, hibiscus, camellia and bamboo are all safe. Cucumber, carrot and lettuce are safe too, which matters if you have a vegetable patch and a dog.

That is a genuinely useful list, because the anxiety usually runs the wrong way round. People worry about the rose bush and ignore the lily on the windowsill. The food equivalent of this page is What You Can Feed a Pet, which does for the fridge and the pantry what this page does for the garden.

For rabbits and guinea pigs there is one more thing, and it is a welfare point rather than a toxicity one: guinea pigs cannot make their own vitamin C and have to get it from food, because they carry a mutated gene for the enzyme that would normally produce it. The MSD Veterinary Manual puts the requirement at 10 mg per kilogram of body weight per day, rising to 30 mg for a pregnant sow. Bell peppers, broccoli, parsley and kale all supply it. If you are sitting guinea pigs and their coat looks rough or they are reluctant to move, that is worth a vet rather than a guess.

Rabbits, Guinea Pigs and Small Pets

This deserves its own section because the risk is structurally different. A dog chews a plant and gets a sore mouth. A rabbit or a guinea pig eats it, and eats a lot of it, and they are built in a way that makes any gut upset more dangerous than it would be in a dog.

The critical fact is that rabbits and guinea pigs cannot vomit. A toxin that goes in cannot come back up, and any disturbance to the gut can escalate into gut stasis, where the digestive system simply stops moving. That is life-threatening in its own right, quite apart from whatever the plant did. So the threshold for ringing a vet is lower, not higher.

The Rabbit Welfare Association and Fund takes the strictest line of any source we found, and it is worth repeating: treat all houseplants as toxic and keep them out of reach. Their reasoning is that few are genuinely safe, and that many plant poisons in rabbits are cumulative, so by the time symptoms show the damage is done.

One identification warning matters more than any other here. Poison hemlock looks like cow parsley, which is a safe forage plant that people pick for rabbits. Hemlock has purple or pink spots on the stem and shinier leaves. The RWAF rule is the right one: if in doubt, leave it. Anything unusual in how they are behaving is worth checking against what unusual behaviour tends to mean, and if medication is involved then giving a pet medication is the practical side. Our guide to sitting for rabbits and small pets covers the day to day, and a pet that has stopped eating is the page to read when a small pet goes off its food, because that is the symptom that matters most.

If Something Has Been Eaten

The order of operations here is short, and it is the same whether it is a houseplant, a garden bulb or a field weed.

Secure the evidence. Get the plant, or the chewed remains, or a photograph of it, and keep it. Identification is the difference between a specific answer and a shrug, and it is the first thing anyone you ring will ask you for. Do not induce vomiting unless a vet tells you to, because it is the right move for some toxins and actively dangerous for others.

Then phone. Ring the owner, ring the 24-hour vet line your platform provides, or ring a local vet, and do it before symptoms rather than after. This is the advice we would give for any situation, and it is worth saying why it is not a burden: most of the time you do not have to take the animal anywhere. If you can describe what was eaten, how much and when, a vet can often tell you over the phone that it is fine, to keep an eye on it, and to ring back if something changes. Vets are busy, and resolving a case in a two-minute call is better for them as well as for you.

That said, some calls end in a car journey, and the two things that decide how that goes are permission and payment. Both are settled before the sit, not during it. Our guide to handling an emergency when the owner is unreachable covers the escalation, and who pays for vet care on a sit covers the money, including whether the practice can bill the owner's card directly. If you are choosing a sitter rather than being one, what to look for in a sitter is the other side of this. Setting all of this up in advance is what the pre-sit questions and the handover checklist are for, and if you carry your own cover then whether a sitter needs insurance explains where it does and does not help.

Where This Research Comes From

We are not vets, and we have not tested any of this on an animal. What we have done is read the primary sources properly rather than repeating what other blogs say, and you should be able to check all of it yourself. Here is where it comes from.

For dogs, cats and horses: the ASPCA Toxic and Non-Toxic Plants database, which is the standard veterinary reference and the source for every plant in the table above, including the safe list. Each plant has its own page: aspca.org/pet-care/animal-poison-control/toxic-and-non-toxic-plants. The clinical signs and toxic principles we quote are theirs.

For rabbits and guinea pigs: the Rabbit Welfare Association and Fund (rabbitwelfare.co.uk), the Royal Veterinary College feeding guidelines, the MSD Veterinary Manual tables on plants and foods harmful to rabbits, the House Rabbit Society, Woodgreen, and the FEDIAF nutritional guidelines for pet rabbits.

For farm animals: the MSD Veterinary Manual's tables of poisonous range plants of temperate North America and its pages on pyrrolizidine alkaloidosis and bracken fern poisoning, plus the British Horse Society on atypical myopathy.

For guinea pig nutrition: the MSD Veterinary Manual on nutritional problems of guinea pigs, RVC, and VCA on vitamin C requirements.

Where sources disagreed with each other, we have said so rather than picking one quietly. The two clearest examples: comfrey is listed as toxic by the RWAF and FEDIAF and as safe by the RVC, and the spider plant is listed as unsuitable for guinea pigs by Woodgreen while the ASPCA lists it as non-toxic to dogs and cats. In both cases we have taken the cautious line and told you why. If you are ever unsure, a vet or an animal poison service beats every page on the internet, including this one.

Conclusion

The honest summary is that most plants are not worth worrying about and a handful absolutely are. Lilies and cats, sago palm and everyone, oleander, yew and foxglove for the heart, ragwort for horses. Learn to recognise those by sight and you have covered almost all of the real risk. If you want the wider safety picture, is house sitting safe is the place to start, and what cannot wait covers the judgement call when something is already happening.

The second half of the job is the part nobody enjoys, which is getting down on the floor and looking at the house from the animal's point of view. What is within reach, what has fallen, what has been left on a low shelf. Five minutes on the first day of a sit, and then again whenever something changes.

And when you are not sure, ring somebody. The call is cheap, it is usually enough on its own, and it is the whole reason we do the research in the first place.

Caro and I have completed 20 house sits across 12 countries, driven 19,000km across Europe in our 1998 VW T4, and saved over $26,500 in accommodation costs over three years of house sitting.

DM us @housesittersguide, we answer everyone.

Frequently Asked Questions

• Are roses poisonous to dogs?

  No. Roses are non-toxic to dogs, cats and horses. The ASPCA lists Rosa species with no toxic principle at all. The real risks are the thorns, and any pesticide or fertiliser that has been applied to the plant.

• Are lilies toxic to dogs or only cats?

  Lilies are the classic cat plant, and dogs are recorded as unaffected. True lilies including Easter lilies cause acute kidney failure in cats. The ASPCA lists the toxic principle as unknown, which means there is no safe amount. If a cat household has lilies, move them.

• Which houseplants are actually dangerous?

  A short list, not a long one. Lilies for cats, sago palm for everyone, kalanchoe, cyclamen, amaryllis and daffodil bulbs in quantity, and rhododendron or azalea. Most other common houseplants, including peace lilies and pothos, cause mouth burning rather than anything worse.

• Is sago palm really that bad?

  Yes, and it is the one people underestimate most. Cycasin causes liver failure and a bleeding disorder, every part of the plant is toxic, and the survival rate is poor even with treatment. It is an ordinary-looking pot plant, which is exactly the problem.

• What should I do if a pet eats a plant?

  Secure the plant, then ring a vet or a poison line before symptoms start. Do not induce vomiting unless a vet tells you to. Most cases are resolved over the phone, and the sooner you call the more useful the call is.

• Are spider plants and Boston ferns safe?

  Both are listed as non-toxic to dogs and cats. Spider plants, Boston ferns, African violets, prayer plants and Christmas cactus are all on the ASPCA safe list. Note that one guinea pig source disagrees about spider plants, so we would not feed one to a small pet.

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