Monday night, while I was attending my Richland County Master Gardener club meeting, one of my friends told me about a weed he wanted to remove from his garden.
From his description, it sounded like a young Giant Hogweed. This sparked a conversation about the importance of using caution when working with this plant.
I emphasized the need to wear gloves, long sleeves, and long pants due to the risks involved. In fact, Giant Hogweed can grow up to 15 feet, making it especially intimidating.
I should also point out a key identifier: its 2- to 4-inch-long, hollow, red-to- purple stem, covered in small bristles.
Reflecting on past experiences, I remembered a friend in Bucyrus who had many of these awful weeds in her gardens. I helped her with the plants shortly after writing my initial column, when I began reporting on this serious weed’s spread across our state.
Over the years, I’ve observed how easily Giant Hogweed is confused with its many relatives, making identification tricky for gardeners.
As we head into weed-pulling season, it’s crucial to know exactly what we’re dealing with to ensure our safety. My friend had been cutting the flowers off the stems to prevent seed production, and she was careful to wear gloves during this process.
Stories like hers reinforce what I’ve learned: Giant Hogweed is even worse than poison ivy and poison hemlock, both of which can be deadly.
The dangers of this weed are very real. Contact with its sap can cause skin burns known as phytophotodermatitis. The visual impact is shocking, too — the pictures I’ve seen are alarming.
The sap alters your skin’s pigment, making you extremely sensitive to sunlight. Affected areas can swell, blister, and even develop permanent scars. Even more concerning, if sap gets in your eyes, it can lead to temporary or even permanent blindness.
I was also asked recently whether or not Giant Hogweed had any benefits. I found this dissertation about the same Giant Hogweed, which had certain medicinal properties. A German pharmaceutical company named this weed the “Medicinal Plant of the Month of July.”
Giant Hogweed, or Heracleum mantegazzianum, is native to the Caucasus Mountains in Europe. Its invasive nature is why it was added to the national noxious weed list — this plant can harm people and livestock, and it’s definitely not native to the U.S.
Because of its fertility, Giant Hogweed can quickly take over an area if left unchecked.
Interestingly, Giant Hogweed shares some life cycle traits with Snap Dragons and Poison Hemlock, as all are biennials. This means they require two years to develop, typically flowering and setting seed in their second year.
What makes Giant Hogweed especially concerning is its ability to produce up to 20,000 seeds from a single plant, enabling it to dominate new environments.
Visually, Giant Hogweed can be deceptive. It resembles Queen Anne’s Lace, which isn’t surprising since both belong to the Apiaceae family, also known as the carrot family.
If you look carefully, you’ll notice similar flower and leaf structures at certain times of the year, though the leaves of Giant Hogweed change as they mature. Another consistent identifier is its hollow stem, marked by purple areas and fine white hairs — a detail worth remembering from earlier in the column.
Giant Hogweed was imported from Europe in 1917 and initially kept in some very upscale gardens in New York. This giant perennial was considered by landscape designers as a potential accent plant.
Designers saw a variety of leaf types and a little purple on the stem, making this a plant of interest. Bottom leaves on Giant Hogweed can get up to 5’ in size towards the end of the season when in moist, fertile soils.
As with most well-intentioned ideas, Giant Hogweed escaped cultivation and has found some success in the wild. Now they are throughout the state.
The best ways to get rid of these toxic weeds are to mow them well before they have a chance to set seed. I suppose that within a few years of mowing these plants faithfully once a week, there would be no seeds out there to grow.
Regular ditch mowing will go a long way to controlling these noxious, poisonous weeds. We should all commend the road crews for the wonderful job they’ve done mowing our ditches this season.
You will also discover that normal herbicides will also manage Giant Hogweed with good practices.
With some patience and the good housekeeping plan of mowing our ditches, we may actually manage this noxious and dangerous plant.
I hope you have a nice stroll through your garden this week. If you have a problem, you can e-mail me at ericlarson546@yahoo.com.