The sun is shining! Planning on spending some time outside? Going for a walk in a natural area or doing some gardening are great ways to unwind while practicing social distancing. But this time of year you could encounter a different danger to public health: poison-hemlock. This noxious weed is common in King County and is toxic if eaten by people or animals. The problem is it looks a lot like other edible plants like carrots and cilantro. Do you know how to identify it?
Hollow stems have purple or reddish blotches and are not hairy. 
First year plants grow in low clumps and can be found year-round.
Young poison-hemlock leaves and roots look like carrots 
Second year plants grow 5 – 10 feet tall with umbrella-shaped clusters of tiny white flowers from April to June.
Weeds don’t always do what we expect of them. Usually poison-hemlock starts flowering in April. But this year after a mild winter and some warm days in February one of our Regional Weed Specialists found plants starting to flower the first week of March!
Poison-hemlock spreads through seeds, so early flowers means early seeds (up to 40,000 per plant!). And if we don’t have a chance to get rid of that plant before the seeds mature that means many, many more baby poison-hemlock plants. Most of the seeds are ready to grow new plants right away, but some of those seeds released will be dormant. This means they hang around in the soil waiting for a signal to start growing. So some of the seeds will wait to sprout in the fall and winter. What this all means is those baby poison-hemlock plants are popping up pretty much year-round. No wonder this weed spreads so quickly!
Poison-hemlock likes sunny sites with moist soils, but it’s not picky. It thrives on roadsides, ditches and disturbed areas like vacant lots in urban areas. We also see it pop up quite often in community gardens, P-Patches, and farms.
This can be downright dangerous if someone confuses poison-hemlock for something they have planted like carrots, parsnip, anise, parsley or cilantro. It has happened in our area before. Every part of the plant is toxic and it can even be deadly. Inhaling the toxins can also make you sick. This can happen if you’re weed-whacking or mowing poison-hemlock plants especially on a hot day or even digging out poison-hemlock plants underneath tree canopy. Extensive skin contact can cause a serious reaction in some people if the toxins are absorbed through the skin. If someone eats poison-hemlock or has symptoms after exposure they need to get medical help immediately. Call poison-control for advice and resources at 1-800-222-1222.
You can help get rid of this weed! If poison-hemlock is on your property dig it up and discard plants in the trash (not the compost).
Always wear gloves, long sleeves and long pants! If you see poison-hemlock on public land or a road right of way let the King County Noxious Weed Control Program know about it. You can report weeds on our King County Connect App or on our website, email us at noxious.weeds@kingcounty.gov or call (206) 477-9333.
More information about poison-hemlock and other weeds is available at https://kingcounty.gov/weeds