Deadly Plants Growing Under the Radar in New York & New Jersey Gardens: What to Know

Bridget Mulroy
Deadly gardening!(Massonstock/iStock)

Gardening is something that so many people have come to love. Whether you’re growing vegetables or only flowers, there is something so gratifying about getting your hands dirty.

While plants are generally seen as zen and aesthetically pleasing, some plants – growing naturally throughout New York and New Jersey – should be weeded out of gardens immediately.


“All parts of all larkspur species are poisonous, but new growth and the seeds contain the highest concentrations of toxic substances,” according to USDA. Larkspur poses the greatest risk to cattle and livestock.


Milkweed poses a risk to cattle and livestock, poisoning has occurred when hay feed has contained the plant or when herds have been enclosed where milkweed grows in high concentrations.
Narcissus poeticus(Bret Wharton/Unsplash)

Narcissus Poeticus

This plant is poisonous to dogs, cats, and horses. According to ASPCA, signs of poisoning in animals from this plant include, “Vomiting, salvation, diarrhea; large ingestions cause convulsions, low blood pressure, tremors, and cardiac arrhythmias. Bulbs are the most poisonous part.”

Rhododendron ponticium

Rhododendron nectar is toxic to species ranging from humans to insects. Death from rhododendron poisoning in humans is less common than in animals and insects. The plant’s toxins are in its tissues, a defense mechanism to protect against being eaten.
Poison Hemlock(dlinca/istock)

Poison Hemlock

As the name suggests, this plant is highly toxic – to both humans and animals. Livestock poses the greatest risk of poisoning as it can be ingested while grazing. All parts of the plant are poisonous. The plant was introduced to the United States as a garden plant from Europe. Knowing what we know now about Poison Hemlock, it’s important to yank it out if you have any growing in your garden.

Poison Oak

Some readers may be familiar with the old rhyme, “leaves of three, let it be…” This is a good rule to follow when thinking about Poison Oak. Growing with shoots of three leaves along a vine, the plant isn’t fatal to humans, but it causes a pretty severe topical allergic reaction in nearly everyone. Most people break out in hives and have an itchy rash that has been known to last for up to a week. This plant is not hard to find between New York and New Jersey, learning to avoid it is imperative.

Poison Ivy

Poison Ivy has nearly the same effect as Poison Oak. While it looks a bit different, if you come into contact with it, you’ll know it.


More commonly known as Deadly Nightshade, two to four of the plant's berries can kill a human child and about ten will kill an adult. While highly toxic, the plant is considered a vital weed in areas where it grows naturally, and it is the main ingredient in Belladonna – the medication eye doctors use (at a highly diluted level) to dilate the pupils in the eye. For years, the plant has been used and abused as finding the balance between its medicinal and poisonous properties has proven to be difficult.


Some readers may already know, that Foxglove and the active chemicals within the plant are the same ingredients in some of the world’s most mainstream heart medications. Despite the plant’s medicinal properties, it grows freely in the area and is highly poisonous if ingested. Symptoms include changes to heartbeat rhythm and blood pressure.

There are so many other plants in the area that continue to go under the radar when considering dangerous plants growing around us. Castor beans, mountain laurels, poison sumac, Lily of the Valley, Tansey, White Berries, and Lantana all bring up concerns for animals as well as humans when these plants are discovered within our gardens.

Do your research! Find all the information you can on a plant before you ingest it!

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