Invasive and Poisonous Plants

Here are 37 basic garden plants you don’t want to grow in your backyard.

When you think of unwanted plants, dandelions, quack grass and other 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.

Invasive Plants

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 beauty, 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.

Purple loosestrife isn’t the only invasive landscape plant causing problems in natural spaces. 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, an area nursery or the Web for a list of invasive species that plague your region.

Keep in mind, however, that it’s possible for a plant to be invasive in one area yet struggle to survive in another. Butterfly bush, tamarisk and ivy are a few plants that are invasive in warmer locales but have a hard time making it in cold, wet or less- than-ideal growing conditions.

Irritating Plants

Gas plant, meadow rue (at left), 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.

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.

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. It’s also a good idea to 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 I know 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, be sure to wear long sleeves and gloves and wash skin immediately.

Poisonous Plants

Just as we weigh the risk of planting 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.

Those with small children and pets may want to avoid planting the very toxic datura 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 mushrooms Mother Nature sometimes scatters in the yard.

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 items from the landscape. After all, we teach them about the risks associated with their indoor environment. Why not do the same for the outdoors?

You should also keep houseplants, seed and bulbs out of the reach of small children and pets. And store all garden chemicals in their original containers in a secure location.

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.

Melinda Myers
Nationally known gardening expert, TV/radio host, author, columnist and speaker.