How To Kill Poison Ivy, According To A Horticulturist

Poison ivy (Toxicodendron radicans) is a vine that contains an oily resin known as urushiol. According to the Centers for Disease Control and Prevention, when the oil comes in contact with the skin, it can result in contact dermatitis, often presenting as a red, itchy rash with blisters or bumps. While poison ivy can be identified (and thus avoided) using a few key indicators outlined in the next section, it’s particularly concerning in areas where children and pets play, as they likely will not know how to differentiate it from other innocuous plants.

“Poison Ivy doesn’t tolerate regular mowing and isn’t often found in maintained lawns, but it can be found along fence lines, in wood piles, and your landscape beds,” says John Kauffman, Ph.D., research scientist at TruGreen. “Poison Ivy is a notorious climber and spread laterally across the ground, in addition to climbing on vertical surfaces.”

Poison ivy grows quickly. Vines can grow as much as 20 feet in a season. With all these creeping, crawling poisonous vines, eradicating them before they prove a larger problem is key. There are several ways to kill poison ivy, whether it’s using a DIY weed killer, a chemical solution, smothering, scalding it with boiling water, or even pulling. As we discuss each eradication method, Kauffman shares his expertise on its pros and cons so you can decide what method is right for you. 

How Poison Ivy Grows

Poison ivy grows as a vine or woody shrub in woodlands, forest edges, and along lakes and rivers. It is native throughout the U.S. and parts of Canada. As a vine, poison ivy grows by aerial rootlets that help it reach lengths of 60-150 feet, climbing along fences, walls, and trees. It grows to 6 feet as a shrub. It’s a perennial that grows during spring and summer, with foliage turning red, orange, or yellow in the fall. It is still poisonous during cooler months.

How To Identify Poison Ivy

“Poison Ivy is probably best identified by its trifoliate leaves, which are a compound leaf made of three leaflets (hence, the old rhyme ‘leaves of three, let it be’),” explains Kauffman. “They are attached to petioles (leaf stalks) that are red in color and may be hairy on older plants.” Kauffman also notes oblong leaflets with smooth margins that sometimes have a notch or lobe on one side can also be useful for identifying the plant. While poison ivy can certainly be avoided if you know what you’re looking for, it's best to try to eliminate the problem in case those who aren’t as well informed find themselves near the vine.

How To Get Rid Of Poison Ivy

Depending on the method you choose, eradicating poison ivy from your yard may take patience and repeat treatments. Here are the pros and cons for different methods of getting rid of poison ivy.

Boiling Water

To kill poison ivy using boiling water, one would drench the plants to scald the tissues and kill the plant. But before you get out your stock pot, be aware that this method might not prove effective in killing the entire plant.

“Boiling water may kill back some of the aboveground tissues but it doesn’t affect the plant crown or roots, which will re-sprout new shoots after the initial scalding,” Kauffman says. “Also, the leaf tissue that remains after scalding still has the urushiol oil on its surface, meaning that you could have an itchy reaction after touching it.” 

Chemicals

According to an article written for Clemson University, both poison ivy and poison oak can be killed with "chemicals that either contain a 3-way herbicide that includes dicamba, mecoprop, and 2,4-D amine or an herbicide that uses triclopyr and glyphosate."

Whichever chemical route you take, Kauffman urges home gardeners to read all labels and directions thoroughly before use. “Some products that control poison ivy may injure your desirable landscape plants if sprayed directly onto them,” he warns. “Other products may injure your lawn grass, so it’s important to read the label and follow the directions carefully.” 

Homemade Weed Killer

Homemade treatments are appealing to those looking to go a more natural route that doesn’t involve powerful chemicals, but Kauffman warns their effectiveness can be hit or miss. “They may not work consistently across a variety of conditions, and they may have difficulty with persistent species like poison ivy,” he says. For that reason, he prefers treatments that leave little to chance. If you choose to go the DIY route, you’ll likely have all the ingredients necessary for a homemade weed killer in your pantry. But this method isn't very effective at eradicating the problem. It may kill the leaves but not the roots, and you may have to repeat the treatment. 

Pulling

“Poison Ivy can be pulled if it’s small, but it can be difficult to fully extract all the underground tissues,” explains Kauffman. “It can also be difficult to avoid getting the urushiol oil from the leaves onto your skin.” That being said, if you’ve already used another method for killing poison ivy and the plant is both brown and dry, it can be a helpful method for clearing it out once and for all (hopefully). Removal by pulling can provide an alternative to chemical methods if dealing with a small plant, though it will not be a suitable option for larger infestations. 

Here's how to pull poison ivy:

1. Start by clipping off any above-ground stems using sharp shears. Tearing apart the stems or ripping them could make the toxic resin airborne.
2. Dispose of plant parts in heavy-duty garden waste bags.
3. Dig out the roots using a small hand shovel before properly disposing of the roots in a garden waste bag. 

Smothering

Smothering poison ivy is all about blocking off both light and oxygen sources the plant uses to thrive, but Kauffman warns it has limited effectiveness due to the nature of the plant. “Poison ivy is well adapted to shaded conditions and situations where other plants may grow overtop of or shade out poison ivy.” 

Here's how to smother poison ivy:

1. Cover the poison ivy with a large plastic tarp and leave it in place for a week.
2. Check to see if the plant is brown and dry. If so, you can then pull the dead weed using the process described in the Pulling section above. If it’s not there yet, replace the tarp and give it another few days to a week.
3. If you’re still not seeing any changes, you might want to consider another method.

How To Dispose of Poison Ivy Safely

Regardless of which method you use, you’ll want to ensure poison ivy is disposed of properly and safely.

1. Protect yourself with gloves, long sleeves, pants, and shoes.
2. Kauffman suggests raking up the poison ivy tissues and placing them in a thick yard waste bag.
3. You can then dispose of them with the rest of your yard waste.

While there are potentially a variety of methods to consider for killing poison ivy, disposing of poison ivy remnants is another story altogether. Both burning and composting should be entirely avoided. “Do not burn poison ivy, since the urushiol that some people find irritating can travel with the smoke and may cause some breathing irritation,” warns Kauffman. And, whatever you do, don’t even think about adding it to your compost as the urushiol could still persist.