Nearly 30 years after King County began its weed control program, the invasive plant garlic mustard has finally been spotted on Vashon Island—and that’s not good news.
Garlic mustard is a Class A Noxious Weed, which means it is written into Washington state law: landowners are legally required to get rid of it. The King County Noxious Weed Program provides technical help, field support, and follow-up visits for anyone who finds this plant.
👉 If you think you have garlic mustard—or another regulated weed—on your property, send a clear photo and the nearest address to: noxious.weeds@kingcounty.gov
Why Garlic Mustard Matters
Unlike most weeds that stick to roadsides and disturbed ground, garlic mustard can sneak into healthy forests and take over. It grows fast in early spring, spreads huge amounts of seed, and even releases chemicals into the soil that block native plants from thriving.
Left unchecked, it can:
- Outcompete wildflowers and understory plants 🌼
- Change soil chemistry and harm fungi that trees rely on 🌲
- Spread quickly once established (every infestation started with a single plant!)
How to Identify Garlic Mustard
Garlic mustard changes looks as it grows, but here are the key things to look for:
- Smell: Crush the leaves or roots—they smell like garlic.
- Leaves:
- First year (low rosette): rounded/kidney-shaped leaves with scalloped edges.
- Second year (tall stalk): triangular, pointy leaves that get smaller up the stem.
- Height: First year = flat to the ground. Second year = 1–3 ft tall.
- Flowers: Tiny white flowers with 4 petals, bloom in spring.
- Seed Pods: Long, skinny, banana-like pods that turn from green to brown.
- Habitat: Dense patches in shady areas, but can grow just about anywhere.
Common Look-Alikes (That Often Fool People)
Lots of local plants get mistaken for garlic mustard. Here are the top ones:
- Money Plant (Honesty) – purple flowers, fuzzy leaves, toothed edges.
- Nipplewort – small yellow flowers, extra lobes at leaf base.
- Ground Ivy / Mints – smaller leaves, square fuzzy stems, minty smell.
- Violets – similar leaves, but lower growing and unique 5-petal flowers.
- Mallows – rounded pleated leaves, can crawl or grow upright.
- Fringe Cups – native, fuzzy stems, tiny fringed flowers.
- Large-Leaf Avens – compound leaves with stacked leaflets, yellow flowers.
- Piggyback Plant – fuzzy leaves that grow tiny baby leaves on top.
- Stinging Nettle – opposite leaves, sharply toothed, square stems, and (of course) it stings!
What To Do If You See Garlic Mustard
- In King County:
Take photos and email them with the nearest address to: noxious.weeds@kingcounty.gov.
Our team will confirm the ID, give you instructions, and in many cases come help with removal. - Elsewhere in Washington:
Contact your county’s noxious weed board. (Every county has one.) - Outside Washington:
Search “[your state] noxious weeds” or “garlic mustard [your state]” for local info. Extension offices and Master Gardeners often help with this.
Bottom Line
Garlic mustard may look harmless, but it’s one of the most damaging weeds we face. Every single plant matters—catching and removing it early means it never has the chance to spread.
See it, smell it, report it. That’s how we keep King County’s forests and backyards healthy.
