Poison ivy has been around forever and may have behaved itself by staying out of our yards and groundcover beds…until now. Every time there is a situation that affects our landscapes, likely a corresponding condition is favoring nature. For example, if you don't mow the lawn for a season, you get an interesting mix of weeds germinating and growing to outcompete the lawn grasses. The same can be said of our perennial beds too. In nature, away from our landscapes, you would expect to find poison ivy in open woods, fence rows, road sides and woodland edges, but it could be just about anywhere.
Poison ivy can and does take on a few forms as it grows and matures. In its smallest form, it sprouts from seed into a seedling that quietly grows in the understory or at the edge of the woods. Later as it becomes more established, poison ivy can become a rambling vine growing along the forest floor or the brush next to your mowed lawn.
While it is still young, you can find it with dull or shiny leaves with some red tinge to them. Poison Ivy does not seek out places to climb, it does take advantage of fences, and small and medium sized shrubs. Without a shrub or fence to grow on, it can grow together creating a shrub on its own.
When poison ivy comes upon a tree, it will change form yet again. As the vine begins to grow up the trunk, the vine creates aerial roots anchoring the vine to the trunk. The sky is the limit in terms of how high it will climb. Old established vines can be several inches in size and each leaf can be quite large, confusing us in identification. As a climbing vine up the tree trunk, the last phase of growth becomes reproductive with flowers and berries with seeds inside.
When you find poison ivy in the yard, it likely will be the young plant just starting out or at the start of vining. One of the best things you can do is show and teach every family member what it looks like so it can be avoided. Not everyone has the same sensitivity or reacts the same, but everyone should know what it looks like and where in the yard it is. Remember, the leaves are in sets of three.
Whenever you work around poison ivy wear plenty of clothes to protect your body. The oil in the stems and leaves causes the dermatitis. In the winter, you can use pruners and carefully cut it out of shrubs or cut and remove the vine as it crawls along the surface. Even in the winter, you can get a mild case of dermatitis from the little oil left in the stems and vines. There are chemical treatments available for controlling this plant. Since it is a woody plant, it will take more time to get it under control and repeated applications are often needed. Read those labels carefully, as some products may only "suppress" poison ivy.
Richard Hentschel is a Horticulture Extension Educator with University of Illinois Extension, serving DuPage, Kane and Kendall counties. Stay tuned to more garden and yard updates with "This Week in the Garden" on Facebook at facebook.com/extensiondkk/videos. The 2017 Kendall County Master Gardener Help Desk currently is open Monday, Wednesday and Friday from 9 a.m. to 12:30 p.m. at 630-553-5823 or at uiemg-kendall@illinois.edu.
About the author: Richard Hentschel’s expertise extends across several subject areas with specialties in lawn care, fruit tree production, woody ornamentals, and home and community gardening. During his 45-year career in horticulture and agriculture, Hentschel became a well-known and respected expert for commercial and homeowner audiences, industry organizations, and media. He retired from University of Illinois Extension in April 2022 with nearly 30 years of service as a Horticulture Specialist and Educator in northern Illinois.