Cat safe plants are the plants graded S0 on this index: non-toxic to cats on the record of the ASPCA or Pet Poison Helpline, with no toxic principle listed — and every other plant here carries a grade from S1 Caution to S4 Emergency, transcribed from the same two sources and reviewed by a person before it is published.
45 of the 107 plants indexed so far are S0. The rest are not hidden behind a paywall or a headline: every S3 and S4 verdict on this site is free, because that is the information that matters most.
Every plant gets exactly one grade per animal, and the grade is a transcription rule, not an opinion. S0 Safe means the source lists the plant as non-toxic with no toxic principle on record; a big meal of any plant can still upset a stomach, and that is the whole risk. S1 Caution means the source describes stomach signs only — vomiting, diarrhea, drooling — with no contact irritation and nothing beyond the gut. S2 Irritant means the source describes a contact irritant, such as the calcium oxalate crystals in pothos and peace lily that burn the mouth, or a milder sign beyond the gut. S3 Toxic means serious systemic effects — heart, breathing, nervous system — or a death that depends on a large amount or a specific part being eaten, as with the bulb of a daffodil. S4 Emergency means death or organ failure from any amount of the plant: true lilies, daylilies, and sago palm.
The colour bar on every verdict page runs green to deep red in that order. Read it left to right as the answer to one question — how much of this plant does it take to hurt a cat — and you have the index. Where two primary sources disagree, the more severe reading wins. Where a plant is missing from both, it is missing from here too: we do not grade from blogs, and we say so on the page rather than guess.
The grid below is the whole index. If you came with a narrower question — flowers, something for a dark corner, a herb pot — start with the list that matches it. Membership on every list is checked against the database at build time: a plant appears only while its cat record is S0.
For anyone who wants a bouquet or a flowering pot without reading a toxicology sheet first. It is a short list on purpose — most cut flowers Americans search for are S1 or worse — and it names the two that people wrongly assume are dangerous.
Rose and orchid both grade S0; the moth orchid is the one most people are surprised by.
For the windowsill collector. "Are succulents poisonous to cats" has no single answer because the difference is species, not luck — so the page lists the safe ones and then, separately, the three succulents cat owners most often already own that are not.
Haworthia and Christmas cactus are S0; aloe and jade are the common S2 surprises.
For the apartment where the only cat-free real estate is the ceiling. The two trailing plants sold everywhere are both S2, so this list matters more than its length suggests.
Spider plant and Boston fern are S0 and hang well; pothos and philodendron are the ones to skip.
For the north-facing room. Low-light plants safe for cats are rarer than the shelf suggests, and the page says exactly how far each one tolerates shade on our care notes rather than promising more.
Parlor palm and calathea are S0; snake plant, the usual low-light recommendation, is S1.
For the kitchen. Most of the culinary windowsill is S0 with no toxic principle on record for any of it, and the page separates those from the herbs that are not — including the one grown for cats.
For the floor. Big statement plants safe for cats are mostly palms, and this is the one list with an S4 warning box, because the most dangerous houseplant in the index is sold as a palm and looks like one.
Areca palm and majesty palm are S0; sago palm is S4 and is not a palm at all.
"The most toxic plant is the one with the scariest name." It is the one with the most ordinary name. The true lily — Easter, Stargazer, Tiger, the bouquet lily — is the top-graded flower in the index and the single plant Americans Google most about cat safety. Its record is short and absolute: the ASPCA lists the toxic principle as unknown and the outcome as "kidney failure, and death is possible"; Pet Poison Helpline's warning covers "any amount of leaf, stem, flower, pollen, vase water, or rhizome." Daylilies are a different genus with the same record. Among houseplants, the top grade belongs to sago palm, where every part contains cycasin, "the seeds most of all," and any amount can cause liver failure and death.
"A poisoning shows itself quickly, so if the cat seems fine, it is fine." Not on this record. Neither source gives a timeline for lilies: every sign — vomiting, loss of appetite, lethargy, abdominal pain, dehydration, acute kidney failure — is listed with onset not specified in source. The instruction Pet Poison Helpline gives instead is "Early treatment is vital … following any exposure." That is why the S4 pages say go now, and why "seems fine" is not information you can act on.
"Cats know not to eat toxic plants." Nothing in the primary-source records supports it. The entries we transcribe describe poisonings that happened, and for the highest grade the exposure route does not even require eating: lily pollen brushed onto fur and groomed off, or a drink from the vase, are both on the toxic-parts list. Instinct is not in the data. The grade is — and on the lily page the grade is the only guard there is.
If you want the index against the world: the 50 plants Americans Google most about cat safety, graded joins US search data to these grades, row by row, and says plainly which of the fifty we have not graded yet. If you want one sheet of paper: the new-cat plant checklist is a printable page and PDF — every S4 plant in the index, every S3, the ten most-searched S0 plants you can keep, and two 24/7 poison hotlines.
Every grade on this site is transcribed from the ASPCA Animal Poison Control plant database or Pet Poison Helpline, never generated, and each verdict page lists its source records with the date we read them and the name and date of the person who reviewed the record before it was published. We are not veterinarians and nothing here is veterinary advice: the grade tells you how seriously to take a chew, and the hotline numbers on every S3 and S4 page tell you who to call. The full method — what makes S0 different from S1, how two disagreeing sources are resolved — is on our About page. How a source becomes a grade →
Any plant graded S0 in this index — currently the largest group in it, and every one of them is on a list above. The S0 grade means the ASPCA or Pet Poison Helpline lists the plant as non-toxic to cats with no toxic principle on record; the only thing left on the record is that a big meal of any plant can upset a stomach. If you want the fast version: spider plant, Boston fern, parlor palm, calathea, orchid, and rose are all S0 and all easy to find. Check the botanical name on the label against the verdict page before you buy: several safe plants share a nickname with a plant that is not.
The true lily (Lilium): S4 Emergency, the highest grade in the index. The ASPCA lists the toxic principle as unknown and records "kidney failure, and death is possible"; Pet Poison Helpline's warning covers "any amount of leaf, stem, flower, pollen, vase water, or rhizome." Daylilies (Hemerocallis) are a different genus with the same S4 record. Plants merely sold as lilies are not in that group: peace lily is S2, and calla lily and Peruvian lily have their own, much milder records. If a cat has had any contact with a true lily or daylily — chewed, brushed, or drunk from the vase — go to a vet immediately, without waiting for symptoms.
The phrase is used online for lilies, and the record explains why it stuck. Neither the ASPCA nor Pet Poison Helpline gives a timeline for when signs appear; every symptom on the lily record — vomiting, loss of appetite, lethargy, abdominal pain, dehydration, acute kidney failure — is listed with onset not specified in source, and the toxic routes include pollen and vase water, which a cat can be exposed to without chewing anything. "Silent" is not a grade, though. S4 is, and Pet Poison Helpline's instruction for it is "Early treatment is vital … following any exposure." Do not wait for a sign to decide.
Nothing in the primary-source records supports that idea. The ASPCA and Pet Poison Helpline entries we transcribe describe poisonings that happened, and for the highest-grade plants the exposure route does not require eating at all: for lilies, pollen and vase water are on the toxic-parts list. Instinct is not in the data; the grade is. Use the grade as the guard, not the cat — keep S3 and S4 plants out of the house rather than out of reach, and call your vet if a cat has had contact with either.
For S1 and S2 plants, out of reach is a reasonable plan: their records describe stomach upset or mouth irritation from chewing, and the verdict pages say what to watch for if it happens anyway. For S4 plants the record removes the option. The lily and daylily records list pollen and vase water among the toxic parts — a cat that never chews can still groom pollen off its coat or drink from a vase — and Pet Poison Helpline's wording is "any amount." The sago palm record says "any part" and "the seeds most of all," and seeds fall. That is why the index binds S4 to one action, remove, rather than to a shelf height.
Because the two sources disagree, and when they do, the more cautious reading is the grade. Peruvian lily is the clearest example: the ASPCA lists Alstroemeria as "Non-Toxic to Dogs, Non-Toxic to Cats," while Pet Poison Helpline records "irritant glycoside phytochemicals" that cause "mild gastrointestinal distress (e.g., vomiting, drooling)." Stomach signs only, no contact irritation, so the plant lands at S1 Caution rather than S2 — and not at S0, because one primary source says there is something to watch for. The grade is not a vote; it is the stricter of the two records.
Often, but not always, and the difference can be the whole story. The lily record for dogs is S0: the ASPCA lists Lilium as non-toxic to dogs and notes that cats are the only species known to be affected by the kidney failure. Sago palm is S4 for both. Every plant with a dog record has its own dog verdict page, reached from the plant's parent page, and the two are graded separately from the same sources rather than copied from each other.