Lovely hydrangeas can produce serious health problems if consumed. Photo by Yoshikazu TAKADA (Flickr)

Even the most innocent-looking of plants can be dangerous if consumed or tampered with. Many common garden plant varieties contain potentially lethal components that can lead to a skin reaction if touched or poisoning if eaten. To avoid these hazards, it’s critical to keep your family, especially children and pets, away from dangerous plants. To alert families to the threats that could be living in their own backyards, I’ve compiled a list of some of the most dangerous plants to avoid.


Gardeners often flock to rhododendron shrubs due to their clusters of brilliantly colored red, white, purple, or pink flowers and accompanying glossy leaves. This spring-blooming plant may appear harmless on the outside, but it is actually a silent killer. Swallow any part of the plant and you’ll experience violent vomiting, a slowed pulse rate, and a diminishing blood pressure. Eat enough and you’ll likely fall into a coma before experiencing death. Due to its danger factor, it’s best to avoid planting this in your yard, especially if you have kids or pets. If it’s consumed, head to the nearest ER for immediate help.

Bleeding Hearts

Bleeding hearts are a popular backyard plant known for their delicate, heart-shaped flowers that bloom in the spring. While beautiful to look at, this plant’s roots and foliage contain alkaloids, which can be toxic if consumed in large amounts. While these flowers are typically not recommended in households with children and pets, they are relatively safe for adults to handle.

Lily of the Valley

Lily of the valley features white, dainty bell-shaped flowers that emit a sweet scent. Unfortunately, the entire plant consists of deadly components that can result in headaches, hallucinations, hot flashes, and skin irritation if consumed. If cut and placed in a flower arrangement, even the water itself can contain deadly traces of convallatoxin. Lily of the valley is only suitable for child- and pet-free households.

Poison Oak

If the name itself doesn’t tip you off, the symptoms it produces will. Poison oak is often found lurking in backyards and local forests and is not always immediately recognized as dangerous. The plant often changes colors with the seasons, developing reddish leaves in the spring, green in the summer, and orange, yellow, or red in the fall. If poison oak comes in contact with the skin, it can cause a number of allergic skin reactions, often consisting of an itchy rash with possible swelling and irritation of the skin. Poison oak is not generally fatal and can be managed in most backyards if caution is taken. The plants should be left out of reach to avoid these side-effects.


Hydrangeas are a common garden plant known for their large blue, pink, and white flower clusters that bloom at the end of summer and into the fall season. Swallowing any part of the plant, especially the flower buds, can cause an overload of the poison cyanogenic glycoside. Shortly after consumption, you may experience dizziness, shortness of breath, rapid pulse, fainting, and a drop in blood pressure. If too much is consumed, convulsions and death can also occur. Keep hydrangeas away from children and pets.