Weeds don’t practice social distancing

Noxious Weed Specialists Karen and Ben work 6 feet apart and wear masks while pulling garlic mustard. (photo by Ben Peterson)

Even though much of King County has been paused under Governor Inslee’s  Stay Home/Stay Healthy order, the weeds aren’t cooperating. Staying home has provided some benefits to our natural environment. You may have heard the uplifting stories about some of these positive environmental impacts: from improved air quality to wildlife returning to Yosemite National Park. But staying home also means leaving natural areas at the mercy of the problems introduced by humans years ago. Without human intervention noxious weeds will continue to spread and endanger our forests, parks, and natural areas. Although protecting public health is our highest priority, the King County Noxious Weed Control Program is also finding ways to control certain high-priority weeds while rigorously following social distancing guidelines.

Field staff are safely separated by at least 6 feet (of garlic mustard). (photo by Erin Haley)

This spring we’re not knocking on doors, meeting folks in their backyards or talking face to face at community events. We are only controlling weeds at sites that we can access without interacting with other people in person. Our scope of work has been narrowed as well. Right now we are laser focused on our top-priority weeds including those that pose a serious risk to human health (poison-hemlock and giant hogweed) and those that pose a serious risk to our shared natural resources. Our spectacular natural environment is something so many of us value about living in King County and our program is continuing our work to protect it, where we can at this time.

See those skinny dark parts under the flowers? Those are garlic mustard seed pods just starting to develop. (photo by Tom Erler)

One species our field staff is focused on right now is garlic mustard. It has been flowering since March and will be ready to release its seeds very soon. If garlic mustard is allowed to go to seed that means we have missed the opportunity to control it for this year. We would have to wait and come back next year when we could expect to find even more plants, which would require more time, energy and resources to control. 

Garlic Mustard: small plants, big problems

At first glance, a single garlic mustard plant doesn’t look like a very big deal. The plants live just 2 years, they usually get only 2-3 feet tall and they are pretty wimpy. If just one popped up in your flower garden you could pull it out, no problem. It won’t poke, burn or poison you, like some other noxious weeds, in fact it was introduced here as an edible plant. But garlic mustard is a monster in disguise.

A single garlic mustard plant can produce up to 5,000 seeds. (photo by Marta Olson)

The problem is, it’s never just one plant, at least not for long. Since garlic mustard can self-fertilize, even one plant can create a huge infestation and massive seed bank. Just one plant can produce up to 5,000 seeds! This plant has all the tools to beat the competition. It is happy growing in sun or full shade which is bad news for our forests.

If left unchecked, garlic mustard will take over the forest floor.

Garlic mustard creates a carpet that first crowds out all our native understory plants and then prevents tree seedlings from growing. This causes serious damage to natural areas and the animals that rely on native plants for habitat and food.

Garlic mustard is trying to make life difficult for this baby Douglas Fir. Good thing our field staff was there to control the weeds! (photo by Sayward Glise)

Garlic mustard is also an excellent impostor! It looks a lot like some common native and introduced species. This means that garlic mustard can be hard to spot, even with a trained eye. As a result new infestations often become large before anyone notices them. If you’re trying to identify a plant take a close look at the leaves. Garlic mustard has smooth, hairless leaves whereas most of the lookalikes are fuzzy.

Garlic mustard has smooth, hairless leaves and small flowers with 4 white petals clustered at the top of the smooth stems. In the spring crushed leaves smell strongly of garlic.
Money plant (Lunaria annua) is often mistaken for garlic mustard. Its stems are fuzzy though and it forms flat coin-like seed pods. Its larger flowers are often pink-purple but are sometimes white. (photo by gailhampshire licensed by CC 2.0)
Fringecup (Tellima grandiflora) also gets mistaken for garlic mustard, but it has very fuzzy stems and leaves. The fringed, bell-shaped flowers form on a long spike. (photo by Ben Legler, used with permission)
Stinging nettles (Urtica dioica) look similar to garlic mustard but they also have fuzzy leaves – you just don’t want to touch them! The flowers are green and dangle in frothy clumps underneath where the leaves meet the square stems.

How you can help

Remember all those seeds I mentioned earlier? This plant gets around very easily by hitching a ride on the bottom of your feet. When our field staff is working at a garlic mustard site they make sure to brush their boots thoroughly before leaving. This means that any wayward seeds stay on site and don’t get spread somewhere else that doesn’t already have a garlic mustard infestation. Boot brushing is actually a great practice that everyone can do to help prevent the spread of noxious weeds. Ever been on a hike in the wilderness and come across a lone herb Robert or Canada thistle plant on the side of the trail? Chances are that seed hitched a ride on a person or animal who didn’t even realize it. Brush your boots and protect your favorite natural places!

Prevent seed stowaways! Brush your boots after a hike or when you get home into a garbage can.

This time of year our field staff is spending a lot of time scrambling around in Seattle’s ravines. These steep, forested pieces of land are sometimes the only remaining forest left in a neighborhood. These pockets of green produce oxygen and keep our neighborhoods cooler on hot days, they protect salmon-bearing streams and are key to Seattle’s identity as the Emerald City. So our field staff brave steep slopes and tripping over mountain beaver dens to control the garlic mustard that threatens these places.

Noxious weed specialist Ashley Shattuck uses a fallen log to help climb the steep slope in order to control hard to reach garlic mustard. (photo by Maria Winkler)

But sometimes they have to brave other hazards like trash and piles of yard waste. Many of these ravines are also infested with yellow archangel and periwinkle, plants that almost certainly spread unintentionally from yards or yard waste piles. This is a good reminder not to put weeds in home compost piles and not to dump in natural areas. Even weeds that look dead can still go to seed or spread by stem fragments. And they are much more difficult to control in ravines than in your backyard!

Please don’t dump in natural areas, that means trash or plants! (photo by Maria Winkler)

If you get an eye for spotting garlic mustard you can help us track it. Report sightings with our King County Connect smartphone app or on our webpage. You can also email us a photo at noxious.weeds@kingcounty.gov if you’re not sure if you have garlic mustard or one of the look-a-likes. And of course, you’re welcome to pull it out if you find it growing on your own property. When you’re done you can even celebrate with a garlic mustard cocktail or some tasty garlic mustard pesto. Just make sure all pieces of the plant you don’t consume go into a plastic bag and into the trash.

First year garlic mustard plants (rosettes) are easy to dig up – make sure they go in the trash not the compost.

The King County Noxious Weed Control Program will keep doing our part to protect the health of our natural environment while we all do our part to protect the public health of our communities.

For more information about garlic mustard or other noxious weeds, visit kingcounty.gov/weeds.


  1. is green purslane a weed? -Tim Malm


    • Thanks for the comment, I’m sorry it took me so long to answer! Common purslane is both a weed and a food. It’s very weedy but it is also edible and used commonly as a food plant too. So it depends on if you want it or not! It’s not considered a noxious weed and it isn’t too hard to control if you decide you don’t want it. Here’s one link, but you will find lots of info online about this plant: http://ipm.ucanr.edu/PMG/PESTNOTES/pn7461.html

Comments are closed.