It’s official – Washington bans sale of six new plants including yellow archangel, butterfly bush and lesser celandine

Effective July 24, the list of prohibited plants in Washington just grew by six. The species added include several popular ornamental plants that are now prohibited from sale: butterfly bush (non-sterile varieties), yellow archangel, lesser celandine and all hybrid non-native hawkweeds, including a type of orange hawkweed that was until very recently still being sold in local stores.

Orange hawkweed in a pot.

The two other species being added are water plants that are not as well known: Senegal tea plant (Gymnocoronis spilanthoides) and Australian water clover (Marsilea mutica). Non-native invasive aquatic plants are some of the hardest to stop once they are established so prevention is often the only sure way to keep them out of our waterways.

Washington’s quarantine law helps stop the continued introduction of plants that are known to cause serious economic or environmental damage in the state. You can see the whole list on the state’s legislative website.

The Washington State Department of Agriculture’s Nursery Inspection Program is the agency that watches over nurseries in our state and that will be tasked with notifying stores about the new banned species. See their website for more information about who to contact if you see any of these species being sold or to find out more information about the quarantine laws.

Even though some of the banned plants have been very popular and useful in landscaping, they are also highly invasive and difficult to control. The negative impacts far outweigh the positive qualities of these plants in our ecosystems. As the WSDA brochure about the quarantine explains: “Escaped ornamentals are one significant source of infestation. It is often difficult to predict which ornamentals will be invasive and aggressive. Scotch broom, purple loosestrife, and kochia are prime examples of plants which have escaped cultivation and caused enormous economic and environmental damage. The quarantines identify plants known to be invasive and a detriment to the state’s natural resources. These regulations will serve to prevent the continued introduction of these problem plants into Washington.”

You can read more about the state’s noxious weed laws and quarantines on the King County website or the Washington State Noxious Weed Control Board website.

yellow archangel infestation in a forest
Yellow archangel infestation in a forest near Ames Lake in King County, Washington.  This plant can be nearly impossible eradicate once it becomes established in a forest.


  1. And yet in that whole list , there is no mention of English Ivy or Himalayan Blackberry. Despite the fact that between them, they have killed or are killing hundreds of trees in Seattle and surrounding areas. I can still buy them both at the store . Please deal with these two deadly killers, before Seattle has no cedars left. It is far beyond ridiculous that they are not on the list and that I still see them for sale. I donate many hours to removing Ivy and blackberry from trees, by the way. It is backbreaking endless work .

    • Thank you for all your backbreaking work removing invasives in our parks! You are right to be frustrated the English ivy and blackberry aren’t on the quarantine list. The quarantine list is established by the Washington State Department of Agriculture’s Nursery Inspection Program. You can find out more about them and get their contact information on their website Your work is so important to help protect our parks and it is very much appreciated, thank you so much!

    • There are plenty of blackberry species that are better choices for food crops – the Himalayan can grow inches per day during the high season, creating dense thickets of viciously barbed stems. There are upright-growing thornless varieties which do not spread aggressively, for instance.

      As someone who had to get a bulldozer in to clear a patch of them near my house some years ago, I can attest that the Himalayans should not be grown in Seattle. The weed patch I cleared was 8 feet high in places, and most of the fruit was inaccessible.

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