10 Garden Plants That Can Kill So Proceed with Caution

by Stacy Tornio

Plants bring beauty, happiness, and countless other benefits. However, they can also have some not-so-great traits, especially when it can involve toxicity. In my new book, Plants That Can Kill, I highlight 101 plant species that are considered toxic, dangerous, and/or sometimes even deadly.

Now don’t use this as an excuse not to garden. Many of these plants are popular in most backyards and are OK to grow, depending on their level and potential danger. But it’s good to know and be aware!

Each plant in the book is rated in one of three ways.

  1. Level 1 indicates a plant that is a nuisance but not necessarily deadly—unless consumed in large quantities. It will likely cause the most harm to pets, but keep an eye out for kids who like to explore with their hands and mouths.
  2. Level 2 indicates a plant that could be harmful (to both pets or humans) in large quantities. You’ll want to keep a close watch if you decide to grow any of these in your backyard.
  3. Level 3 indicates a plant you want to stay away from. It likely has been linked to death (both humans and animals). Don’t plant it in your backyard. It’s not worth the risk.

Here are snippets of 10 plants from my book. To learn more about them and others, pick up a copy of Plants That Can Kill on Amazon!

1. Azalea (Level 2)

You can find dozens upon dozens of azaleas to choose from both online and at your local garden center. They are some of the most popular shrubs for backyard gardens, especially in warmer climates. Gardeners love azaleas because they reach their mature size in just a few short years, and then they are reliable bloomers for many more years in the future. Don’t let kids or pets eat the flowers, leaves, fruits, or seeds of this plant. Mild symptoms might include mouth irritation, nausea, and vomiting. However, large consumptions can be quite serious!

2. Yew (Level 3)

Yews are one of the longest-living evergreens, and they are a staple in many backyards. You’ve probably seen a yew, even if you didn’t know what it was. While the entire yew family (Taxus) is huge and include both trees and shrubs, they are very common as backyard shrubs. Plus the berries can seem really appealing to young kids. Pretty much all parts of yews (especially the evergreen needles) can cause some serious heart problems if consumed. If left undetected or untreated, it could lead to death.


3. English ivy (Level 2)

Here’s another vine that is a staple in the houseplant world. Actually, it’s a staple in many gardens, too. It can reach crazy heights of 80 feet in an outdoor setting. Indoors, it can trail quite a bit, too, especially if it has something to grow up or around. If ingested, humans or animals might experience difficulty breathing, convulsions, vomiting, and paralysis or coma in extreme cases! Outside, the plant could produce berries, too, so that’s another thing to watch for.


4. Jade plant (Level 2)

The jade plant has a bit of good superstition behind it. For years, people have been giving it as a gift because they believe it will bring the receiver wealth and good fortune. So it’s a popular houseplant given for a new job, new home, etc. However, if you have pets at all, it might not be the best houseplant for you. Take a look. All parts, including the leaves, which are especially appealing to pets because of their small size.


5. Clematis (Level 1)

Clematis is one of the most popular vines in the garden. There are many different types of clematis out there, and the beautiful flowers that this plant is known for come in many different shades. Clematis can cause mouth pain to animals who eat it. Other side effects include vomiting, salivating, and diarrhea. It’s probably fine for most backyards and gardens, but keep it away from pets.


6. Foxglove (Level 2)

This is a very popular garden plant with its tall and cascading bell-shaped flowers. It has some fun nicknames, including fairy bells and dead man’s bells. (This is your hint that it is, in fact, deadly.) When a human or animal eats this plant, the digestion of it can produce a substance called digitalis that affects heart muscles, which can in turn, may lead to a heart attack. You will see vomiting first, so seek medical attention immediately!


7. Oleander (Level 3)

Oleander is one of the most deceiving plants out there. Home gardeners have been growing it for years—they love this small shrub for its beautiful blooms. Plus, it’s relatively easy and fast to grow. But consider this your word of warning because oleander is one of the most deadly and toxic plants around. Consuming any part of this shrub—the leaves, bark, flowers, sap—can result in some pretty serious consequences or even death. Some of the toxic elements in oleander include cardiac glycosides, saponins, digitoxigenin, oleandrin, oleondroside, and nerioside. These can cause vomiting, dizziness, vision problems, and other issues like death. Stay away!


8. Angel’s trumpet (Level 3)

How can a plant with such a sweet name be dangerous? These are popular (and beautiful) plants that gardeners have been growing for centuries, but they are also some of the most deadly backyard plants. Most know this plant for its unique trumpet-shaped blooms. However, all plants can cause serious problems. Even handling the plants can cause skin irritation. So this is a “look but don’t touch” plant. And unfortunately (spoiler alert!), it’s not really a recommended backyard plant. If the elements of this plant enter the bloodstream, it might bring on symptoms of muscle weakness, dry mouth, rapid pulse, fever, and hallucinations. Other serious symptoms could be paralysis, convulsions, and death. The seed pods (which can look like fruit) have the most concentrated toxicity and are most dangerous.


9. Cardinal flower (Level 1)

Cardinal flower is known among gardeners as a great plant for hummingbirds (they do love the color red). It’s also a popular option for butterflies. This native perennial is a great one to get started in your garden. The flowers are bold and beautiful, and once you get this plant established, you’ll have great blooms for many years to come. Pets who eat parts of this plant, especially in large quantities, might experience of depression, vomiting, excess salivation, and abdominal pain.


10. Rhubarb (Level 2)

Many gardeners consider rhubarb a perennial. Hardy in zones 3 to 8, rhubarb definitely deserves a spot in your flower bed, not just in your veggie garden. It’s one of the earliest things to grow in spring and has beautiful green leaves and pinkish red stalks. Once you harvest and cook these stalks, you’ll definitely want to try your hand at making a rhubarb pie (or rhubarb strawberry pie). Just stay away from the leaves, though. The leaves contain something called oxalic acid, which can cause kidney failure in humans! Of course, you’d need a lot of leaves for this to happen, but it’s still not a good idea to eat them. This is still a good option for your garden, unless you have a pet that likes to munch away a lot.


Love to garden? Check out these plants that are easy to grow and hard to kill in your backyard.

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