Poisonous, Irritating and Invasive Plants You Should Never Grow

Some plants look pretty, but they are invasive, irritating to skin or poisonous. Avoid these toxic, irritating and invasive plants.

When you think of unwanted plants, dandelions, quack grass and other common weeds that bully their way into your yard and garden probably come to mind. But, occasionally, we inadvertently plant a seedy character that either takes over the garden, gets you itching or causes a whopper of a stomachache (or worse) if eaten. Discover the worst irritating, poisonous and invasive plants you should avoid. And here’s how to remove invasive plant species for good.

The Most Common Invasive Plants in North America

KudzuMartha Snider/Getty Images
Kudzu spreads rapidly
  • Barberries
  • Buckthorn
  • Chinese and Japanese wisterias
  • English ivy
  • Garlic mustard
  • Japanese honeysuckle
  • Japanese knotweed
  • Kudzu
  • Oriental bittersweet
  • Purple loosestrife
  • Queen Anne’s lace
  • Tree-of-heaven

Purple Loosestrife

Shutterstock 1151566937Przemyslaw Muszynski/Shutterstock
Purple loosestrife looks pretty but should be removed

It’s covered with pretty, purple flower spikes from late summer through fall. A long-lived perennial, it adapts to a wide range of growing conditions. Plus, it makes a beautiful cut flower. It’s a gardener’s dream come true, right? Wrong!

I’m talking about purple loosestrife. And as many gardeners throughout the United States and Canada know, this invasive blooming plant, which has taken over many a backyard garden, has now taken to our natural wetlands. A vigorous grower, it crowds out native plants, eliminating cover and essential food sources needed by wetland wildlife.

Buckthorn and Honeysuckle

Buckthorn, invasive plantsJeff Wallager/Getty Images
Buckthorn is shown in early fall in Minnesota.

Purple loosestrife isn’t the only invasive plant causing problems in natural landscapes. Norway and Amur maples have joined buckthorn and honeysuckle as woodland invaders.

The lesson here? Do a little research before adding new plants to your landscape. Select plants suited for the growing conditions in your backyard. Then, check with your local extension service or an area nursery for a list of invasive plants that plague your region.

Butterfly Bush

butterfly bushCourtesy Ella Clem
Butterfly bush can be invasive, so look for sterile cultivars

Keep in mind, however, that it’s possible for invasive plants in one area to struggle to survive in another. Butterfly bush, tamarisk and ivy are a few that are invasive plants in warmer locales but have a hard time making it in cold, wet or less- than-ideal growing conditions. Check with your local university extension service to see if these plants are considered to be invasive in your area.

Check out some alternatives to invasive shrubs.

Plants That Cause Skin Irritation

Shutterstock 1097057009T-I/Shutterstock
Garlic mustard

Gas plant, meadow rue, euphorbia and hyacinths are common landscape plants that can leave some gardeners covered with an itchy, red rash. Though the list of potential irritation-inducing plants is long, not all gardeners will be affected by some—or even any—of these plants.

The best tactics to avoid the itch are to be careful about what you plant, be diligent about wearing protective garden garb and learn maintenance strategies that’ll keep your landscape looking good…and your skin rash-free.

Wild Parsnip - Pastinaca sativaChimperil59/Getty Images
Wild parsnip makes many people break out in a rash similar to poison ivy.

Start by taking note on how the offending plant causes the rash, and make changes based on that information. For instance, some gardeners with sensitive skin develop a rash after only a few minutes of handling prickly plants. If this is you, be sure to wear heavy clothing and leather gloves, or convince your thicker-skinned gardening friends to help out.

Poison Ivy (Rhus radicans) a poisonous plantEd Reschke/Getty Images
Avoid contact with poison ivy

Infamous plants like poison ivy or even some ornamental euphorbias also contain irritants in their saps that result in a painful and itchy rash. Don long sleeves if you plan to garden around or weed these irritants out of your landscape. Immediately wash the irritating oils off your body and clothing to avoid further exposure and expansion of the rash.

Oddly enough, gas plant, wild parsnip and garlic mustard sap cause a rash only when the irritating oils are exposed to sunlight. That’s why some gardeners weed at dusk or by their landscape lighting to eliminate the risk. But if you can work around these irritants only by the light of day, wear long sleeves and gloves and wash skin immediately.

Psst—we found 8 mosquito-repelling plants you need in your yard ASAP.

Poisonous Plants

DaturaCourtesy Crystal Seoane
All parts of the datura plant, especially the seeds and leaves, are extremely poisonous.

Just as we weigh the risk of planting rash and allergy-inducing plants in the landscape, we do the same for poisonous plants. It may surprise you to learn just how many of your favorite plants can cause stomachaches, diarrhea or even death when eaten. But let’s take a realistic look at living with potentially poisonous landscape plants before leveling our garden beds and switching to artificial turf and silk flowers.

A yew bush with bright red berriesajt/Getty Images
Yew berry seeds are poisonous

Those with small children and pets may want to avoid planting the very toxic datura, commonly known as Jimson weed, and castor bean. The seed in the fleshy red fruit of the yew, the nuts of horse chestnut trees and all parts of the oleander plant are also toxic. And let’s not forget the wild mushrooms Mother Nature sometimes scatters in the yard. Try growing an indoor mushroom kit instead!

Poisonous mushroomsLinda J Smith
Some mushrooms are poisonous, like this fly agaric mushroom.

That said, perhaps the most important thing we can do for our children is to curb their sense of adventure when it comes to eating wild plants. You should also keep houseplants, seeds and bulbs out of the reach of small children and pets. And store all garden chemicals in their original containers in a secure location. And try natural ways to kill weeds and eliminate insect pests rather than noxious chemicals.

Lastly, reduce the risk by identifying and labeling all your landscape plants. As a gardener, it is great to have a record of what’s planted where. But as a parent or pet owner, you never know when this kind of information will be useful in the case of an emergency.

Next, learn about edible flowers that are safe to eat.

Popular Videos

Melinda Myers
Melinda Myers is a nature and gardening writer whose specialty is attracting wildlife, especially birds, to the garden. She contributes regularly to the magazine Birds & Blooms, and lectures widely on creating gardens that please both human and avian visitors.