When planning your garden, it’s important to consider not only the beauty and aesthetics of the plants you choose, but also their potential impact on the environment and your health.

Some plants may appear harmless, but can actually wreak havoc on your garden and surrounding ecosystem.

Certain plants can be aggressive invaders, quickly taking over and choking out native plant species. Others release compounds from their roots that can harm or kill nearby plants. And some plants are even toxic to pets and humans, causing serious health issues if ingested.

In this article, we’ll explore some of the most dangerous plants to be aware of and provide tips on how to minimize the risks they pose.

12. Foxglove (Digitalis purpurea)

Foxglove Digitalis purpurea
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Foxglove, also known as Digitalis purpurea, is a beautiful ornamental plant that is commonly found in gardens.

It is a biennial plant that grows tall and produces bell-shaped flowers. However, it has become invasive in some areas, particularly along the east and west coasts, where it has spread to natural roadsides.

While foxglove has medical uses and can be used to treat heart failure, it is also a dangerous plant.

The compounds in the plant can slow down the heart or cause an irregular beat, which can lead to life-threatening effects.

It is important to note that eating any part of the plant or making tea from its leaves can be extremely risky.

Therefore, it is advised to keep this pretty plant away from children and not to attempt to make your own heart medicine.

If you are looking to add foxglove to your garden, it is important to be aware of its potential dangers and take necessary precautions.

1. Burning Bush (Euonymus alatus)

Burning Bush Euonymus alatus
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Burning bush, also known as Euonymus alatus, is a popular landscape shrub due to its bright red fall color and ability to thrive in various growing conditions.

This non-native shrub can grow in both sun and shade, with the exception of wet and poorly draining soil.

Burning bush is often used in cultivated landscapes, but its biggest strength lies in its ability to outcompete other plants in natural areas.

However, it is important to note that burning bush is toxic if ingested in large quantities. This includes all parts of the plant, as well as its sap and seeds.

It is especially important to keep burning bush away from children, as they are more susceptible to the toxic effects.

Additionally, birds are known to eat the small fruits produced by burning bush and deposit the seeds along their flight path, potentially spreading the plant to new areas.

8. Trumpet Vine (Campsis radicans)

Trumpet Vine Campsis radicans
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If you want to attract hummingbirds to your garden, trumpet vine is a great option.

This woody perennial vine is known for its aggressive growth and can take over a landscape quickly with warmth and moisture. However, if you live in an arid climate, trumpet vine tends to be better behaved.

It’s important to keep this potentially invasive spreader in check by growing it on a strong trellis away from trees and shrubs that it could potentially strangle.

Additionally, it’s best to avoid planting it near foundations, sidewalks, and driveways, where its roots can damage them.

Trumpet vine is also highly flammable, so keeping it away from structures is important.

2. English Ivy (Hedera helix)

English Ivy Hedera helix
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English ivy, also known as Hedera helix, is a fast-spreading ground cover that can quickly take over an area and suppress all other vegetation.

When grown as a vine, it can even swallow entire trees and shrubs, blocking sunlight and leading to the slow death of the host plant. The weight of the ivy can also break limbs and weaken woody plants, making them more susceptible to disease.

Native to Europe and Western Asia, English ivy produces tiny black berries that are favored and spread by birds. However, it is considered an invasive plant and can cause severe skin irritation due to the cell sap it produces.

Therefore, it is not recommended to add this plant to your landscape.

To avoid the negative effects of English ivy, it is important to regularly monitor and remove any plants that may be growing in your yard. By doing so, you can help protect the health of your other plants and the surrounding wildlife.

3. Callery Pear (Pyrus calleryana)

Callery Pear Pyrus calleryana
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Callery pear, also known as Bradford pear, has been a popular flowering tree in home landscapes since the 1950s. This fast-growing tree was favored by home builders due to its showy appearance and lack of messy fruits.

However, new cultivars designed for better strength have resulted in an invasion of fruit-producing Callery pear trees that can inter-breed and dominate the edges of forests and open fields.

The Callery pear is considered invasive in many states and has been banned in Ohio, Pennsylvania, and South Carolina. Its saplings can outcompete native vegetation, causing a decline in biodiversity.

Therefore, it is important to avoid planting Callery pear in your yard and opt for non-invasive alternatives instead.

4. Deadly Nightshade (Atropa belladonna)

Deadly Nightshade Atropa belladonna
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If you’re planning a garden or exploring natural areas, you should be aware of deadly nightshade, also known as belladonna.

This highly toxic plant is a member of the nightshade family and is found throughout Europe and Asia, as well as in some areas of disturbed soil in the United States.

Deadly nightshade is called “deadly” for a reason – even touching it with an open wound can be fatal, and eating its berries can also lead to death.

It’s important to note that while deadly nightshade is harmful to humans and pets, some birds and wildlife are not affected by it.

Additionally, the plant has traditional and modern uses in medical preparations, such as dilating pupils and easing some stomach conditions. However, these uses should only be attempted by professionals at low doses.

To avoid the dangers of deadly nightshade, it’s best to steer clear of this plant altogether and focus on safer options for your garden or foraging expeditions.

6. Daffodils (Narcissus spp.)

Daffodils Narcissus spp
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Daffodils are a common sight in gardens during springtime. However, it is important to note that all parts of the plant, including the bulbs, are toxic to both humans and pets.

If ingested, daffodils can cause gastrointestinal problems, excessive drooling, and in severe cases, convulsions and heart issues.

Pet owners should be especially cautious if their furry friends have a tendency to dig or sample plants. Keep daffodils out of reach to prevent any potential harm.

7. Angel’s Trumpet (Brugmansia spp.)

Angels Trumpet Brugmansia spp
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Angel’s trumpet, also known as Brugmansia, is a poisonous shrub native to South America.

Despite its poisonous nature, it is commonly grown in containers in cooler climates for its highly fragrant, 20-inch-long flowers that attract hummingbirds.

It is important to note that all parts of the plant are toxic to both people and animals, and accidental poisoning can occur when its sap enters the bloodstream.

Gardeners who handle the plant should wear gloves when pruning it and be careful to clean up fallen leaves.

9. Death Camas (Zigadenus venenosus)

Death Camas Zigadenus venenosus
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If you’re out in the wild and come across a plant that looks like wild onion, be careful. It might be death camas, a poisonous plant native to North America.

Death camas grows from a bulb resembling an onion, and its grass-like leaves emerge in early spring. The plant produces small bunches of delicate white flowers in late spring.

All parts of the plant are toxic, making it a danger to livestock and grazing wildlife. Be sure to avoid contact with this plant to prevent any harmful effects.

10. Castor Bean Plant (Ricinus communis)

Castor Bean Plant Ricinus communis
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The Castor Bean Plant is a popular addition to gardens and containers due to its large, star-shaped leaves that add an exotic touch.

However, it is important to note that all parts of the plant are poisonous, with the seeds being especially toxic.

The seeds develop inside spined capsules and can explode when mature, releasing themselves as projectiles all over the garden.

This can be dangerous for curious pets and small children, who may accidentally ingest them or spread them to other areas.

To prevent unintended spread and accidental ingestion, removing castor bean seed capsules when they appear and keeping children away from the plant is recommended.

11. Water Hemlock (Cicuta douglasii or C. maculata L. var. californica)

Water Hemlock
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Beware of Water Hemlock, a deadly plant that can kill both people and livestock.

This plant is commonly found growing along streams, bogs, or ditches and can be mistaken for Queen Anne’s lace, a harmless florist staple.

There are two main types of Water Hemlock: Cicuta douglasii and C. maculata. The former grows in wetter northwestern climates, while the latter is found throughout North America.

Water Hemlock contains alkaloids that can be fatal to people within just 15 minutes of ingestion and can kill livestock within a few hours. The roots of this plant are even more poisonous than the above-ground parts.

It is important to avoid this plant at all costs and not confuse it with similar-looking florals or edibles like wild parsnip or celery.

13. Black Walnut (Juglans nigra)

Black Walnut Juglans nigra
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If you’re a fan of baking, you may have used black walnuts in your recipes. These nuts come from the black walnut tree, which is also Missouri’s official state tree.

While the nuts are safe for human consumption, the tree produces a toxic substance called juglone that can harm other plants trying to grow nearby.

It’s important to avoid planting anything other than inedible, shade-loving plants within the area under the tree’s canopy.

Some plants, such as tomatoes, peppers, and potatoes, are particularly vulnerable to juglone’s effects. Lilacs, peonies, and azaleas may also struggle to grow near black walnut trees.

However, research on the tree’s harm varies, so it’s best to err on the side of caution.

Despite its potential to harm other plants, the black walnut tree provides many benefits. It’s a source of food for people, mice, and squirrels, hosts some moths, and provides shade and spring flowers.

By being mindful of what you plant near the tree, you can enjoy its benefits without causing harm to other plants in your garden.

14. Oleander (Nerium oleander)

Oleander Nerium oleander
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If you live in USDA Zones 9 and 10 and are looking for a heat-loving shrub that can handle heavy pruning, oleander might be a great choice for you. This evergreen shrub is popular for its attractive appearance and prolific summer blooms.

However, it’s important to note that oleander contains two toxic compounds throughout the plant, which can cause severe illness or even death if ingested. Symptoms can include nausea, vomiting, and abnormalities in heart function.

Even burning cut oleander branches can generate smoke that may cause severe reactions, and some livestock have become ill from eating the plant’s parts. It’s also important to avoid touching the sap, as it can cause skin irritation.

Despite these risks, oleander remains a favorite flowering hedge or specimen plant throughout the United States. Just be sure to exercise caution and keep kids and pets away from it.