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Ferns are not a recommended food for chickens: some common ferns, especially bracken, are poisonous to livestock, and very little research shows which ferns are safe for poultry. A hen that nibbles a houseplant frond is unlikely to be in danger, but there is no good reason to feed ferns on purpose. This guide explains which ferns are known to be toxic, what the research does and does not say, and how to keep a free-ranging flock safe.
Key Takeaways
- Bracken fern is poisonous to cattle, sheep, horses and pigs, and every part of the plant contains a cancer-causing toxin.
- Asparagus fern is not a true fern, and its berries and sap are toxic to pets.
- Boston fern is listed as non-toxic to dogs and cats, but it has not been studied in chickens.
- Ferns add little nutrition; a complete feed and fresh water meet your flock’s needs.
- Chickens do not truly vomit, so don’t wait for vomiting as a sign of poisoning.
Correction: an earlier version of this article said chickens can eat ferns without qualification, described asparagus fern as non-toxic and ‘brake fern’ as safe, contradicted itself about Boston and maidenhair ferns, and listed vomiting as a symptom; these errors have been removed.
The short answer on chickens and ferns
Toxic plant databases such as the ASPCA’s cover dogs, cats and horses, not chickens. The Merck Veterinary Manual’s chapter on fern poisoning covers cattle, sheep, goats, horses and pigs. None of these sources gives a list of ferns that are proven safe for poultry.
That gap matters because ferns are hard to tell apart and some are genuinely dangerous. It also means ferns are not worth the risk: they are not a useful source of nutrition for chickens. University of Maine Extension notes that young, tender plants can be a helpful supplement, but old, fibrous plants are poorly digested and of little value.
Bracken fern: the one to worry about
Bracken (Pteridium aquilinum) grows around the world, usually in partly shaded, well-drained open woods, pastures and clearings. According to the Merck Veterinary Manual, it contains two main toxins:
- Thiaminases, enzymes that destroy thiamine (vitamin B1). Thiaminase poisoning mainly affects horses and pigs and causes signs of thiamine deficiency.
- Ptaquiloside, a toxin that damages bone marrow and causes cancers in cattle and sheep. It can also reach people through milk from cows that eat bracken.
All parts of bracken contain ptaquiloside, including the young, unfolding fronds. Merck describes bracken poisoning, apart from thiamine deficiency, as essentially untreatable. How bracken affects chickens has not been well studied, so the sensible choice is to keep your flock away from it.
Be careful with common names. The ASPCA lists ‘brake fern’ as another name for bracken, even though garden centers also sell Pteris species as brake ferns. If you are not sure what you have, treat it as bracken.
Asparagus fern is not a fern, and it is toxic
Asparagus fern (Asparagus setaceus and A. densiflorus) is a popular houseplant and landscape plant. North Carolina State Extension points out that it is not a fern at all: it belongs to the asparagus family.
Its berries and sap contain sapogenins. The ASPCA lists asparagus fern as toxic to dogs and cats, and eating the berries can cause vomiting, abdominal pain and diarrhea in pets and people. The stems also carry sharp spines. Keep it out of reach of your chickens.
What about Boston, maidenhair and other ferns?
| Plant | What the evidence says | Advice for chickens |
|---|---|---|
| Bracken / brake fern (Pteridium) | Poisonous to livestock; carcinogenic; toxic to horses (ASPCA) | Keep chickens away |
| Asparagus fern (Asparagus spp.) | Toxic to dogs and cats; berries and sap contain sapogenins | Keep chickens away |
| Boston fern (Nephrolepis exaltata) | Non-toxic to dogs and cats (ASPCA); no chicken data | Low concern if nibbled; don’t feed on purpose |
| Other garden and wild ferns | Little or no poultry-specific research | Don’t feed; identify before letting chickens graze |
You may see maidenhair, bird’s nest, sword, lady or sensitive ferns described online as ‘safe for chickens’. None of the veterinary and extension sources used for this article supports those claims for poultry, so treat them as unknowns.
Signs of plant poisoning and when to call a vet
Chickens do not show true vomiting, so poisoning often looks vague. Watch for:
- Lethargy or weakness
- Loss of appetite
- Diarrhea or unusual droppings
- Wobbliness, trouble standing or other odd behavior
These signs are common to many illnesses, not just plant poisoning. If a bird seems unwell, separate it, make sure it has clean water, and contact a veterinarian. Take a sample of any plant you think it ate. Our overview of chicken diseases and symptoms can help you describe what you are seeing.
Keeping a free-ranging flock safe
- Walk your chickens’ range and identify ferns before letting birds graze there. Remove or fence off bracken.
- Keep houseplants such as asparagus fern out of coops and porches your chickens can reach.
- Don’t feed clippings or greens that have recently been treated with pesticides.
- Choose coop-side plants with care; see what to plant next to a chicken coop and our guide on keeping chickens out of the garden.
- Keep treats, including greens, to less than 10% of the diet, with a complete feed making up the rest.
FAQs
My chicken ate a bit of a Boston fern. Should I worry?
Boston fern is listed by the ASPCA as non-toxic to dogs and cats, so a small nibble is unlikely to be a problem. Watch the bird and call a vet if it seems unwell.
Is bracken fern toxic to chickens?
Bracken is poisonous to livestock and contains a carcinogen in all parts of the plant. It has not been well studied in chickens, so keep your flock away from it.
Can washing ferns make them safe?
No. Washing removes dirt and surface residues, not toxins that are part of the plant itself.
Do ferns provide useful nutrition for chickens?
Not in any meaningful way. Old, fibrous plants are poorly digested by chickens, and a complete feed already supplies what they need.
Conclusion
Ferns are not a food your chickens need, and some, like bracken and asparagus fern, are known to be toxic to animals. Identify the ferns on your property, keep chickens away from the risky ones, and stick to a complete feed with small amounts of safer treats. Call a veterinarian if a bird seems ill after eating plants.
Sources
- Merck Veterinary Manual: Bracken Fern and Other Fern Poisoning in Animals
- ASPCA: Toxic and Non-Toxic Plant List – Horses
- ASPCA: Toxic and Non-toxic Plants: Asparagus Fern
- NC State Extension Gardener Plant Toolbox: Asparagus setaceus
- ASPCA: Toxic and Non-toxic Plants: Boston Fern
- University of Maine Extension: Nutrition for Backyard Chicken Flocks in Maine
- Journal of Poultry Science (PMC): Copper sulfate, vomiting, retching and nausea-like responses in chicks
- University of Illinois College of Veterinary Medicine: Care and Feeding of Backyard Chickens
Checked September 2026. Labels change, so always read the label on the product you buy. See our editorial policy for how we research health articles.
