Poison Hemlock Eradication

Several articles have shown up recently about poison hemlock. It does grow here in the Ozarks and this is my poison hemlock eradication method.

There was a stretch of this plant along the road by the barn. It was a hundred feet long and several feet wide when I began getting rid of it.

look for plant for poison hemlock eradication
Early in the spring the distinctive leaves appear in rosettes. These can be dug out by the roots. Once the flower stalk shoots upward, its size and shape make it easy to spot. It is normally a single stalk an inch or more in diameter growing up to seven feet tall. Queen Anne’s Lace has slender stalks and is rarely over three feet tall.

I don’t use herbicides normally and didn’t want to for this. A row of asparagus was behind part of this stretch. Elderberry and day lily were growing there too.

Poison hemlock is considered the second most toxic plant in Missouri (Number one is the invasive water hemlock.). It can grow as an annual to a short lived perennial, but is mostly a biennial. That means it has a rosette of leaves one year and blooms, then dies the next year.

flowers key to poison hemlock eradication
Once poison hemlock flowers open, they are quickly pollinated. They will form seeds, even if the plant is cut down. The flowers are in groups forming a loose umbel. The flower stalks come from any leaf node on the flowering stalk.

My poison hemlock eradication method made use of this life cycle. When the plants put up their flower stalk, I cut them down. The plant died.

There is a drawback to this. Once the flowers open and are pollinated, they will set seed. Any surviving seed means more plants.

poison hemlock leaf
Although other plants have lacy leaves, the poison hemlock leaves are easily identified. They are large with a long center stem. The leaflets are in pairs, large near the base and small near the tip, making the leaf strongly triangular. Wild carrot or Queen Anne’s Lace does have lacy leaves, but they are much smaller without the strong triangular shape.

I stuffed the flower stalks in empty feed sacks and let them dry. Where I live I can burn my trash in a burning barrel and, once the plants were thoroughly dry, I burned them.

The first year was the worst in terms of the number of plants to cut down. The second year was not much better. By the third year there was a definite drop in the number of plants.

My poison hemlock eradication method does take dedication. Gloves are a good idea, although I rarely use them. Keep the sap off your hands, etc. and wash up right afterwards. The poison danger is from ingesting (eating) the plant or its sap.

poison hemlock stem
The poison hemlock stalk is smooth. The background color is light green. Purple splotches and streaks color most of the stem. It is hollow. To eradicate poison hemlock, cut the stalk at the base. Try to get all the leaves leaving no nodes to put up a second smaller stalk. It is not necessary to treat the root as it will die on its own. Cut the stem into smaller lengths to make bagging and disposal easier. Try to keep the sap off the skin.

This year I found a few plants trying to grow near the asparagus row. They were easily dug up and disposed of. Three bloomed and were similarly dealt with.

It was a lot of work, but I consider my poison hemlock eradication method a success.

I have plant pages posted several years ago on water hemlock. It has a general plant description with pictures.