Some weeds just won’t die, even after they are uprooted. Tossing them on a brush pile might actually give them a second chance at life. Yellow archangel infestations often start from yard waste piles or discarded container plantings.
Tansy ragwort will make a fairy ring of new plants around burn piles because the seeds spread in the air as the plants burn. Scotch broom seeds can survive being buried for decades, only to germinate when they are exposed to the elements again. And don’t get me started on how durable knotweed rhizomes are!
A good rule of thumb with noxious weed disposal is to safely dispose of the weeds instead of trying to compost or burn them at home. For noxious weeds that are poisonous or regulated in your county, use garbage bags and discard in the trash. If you are in King County, the noxious weed program will send you vouchers for free disposal of regulated noxious weeds at county transfer stations. Just contact the program to request a voucher.
Time-saver tip for King County residents: Customers heading to the Algona, Bow Lake, Factoria, Houghton, Renton, or Shoreline transfer stations can now view the line of vehicles waiting to enter the stations and see average disposal times. Photos of transfer station entrances are updated every 60 seconds to give customers a real-time awareness of the line of vehicles in the queue, and disposal times list how long it is currently taking customers to complete their visit after they have weighed in at the scale house. Visit www.kingcounty.gov/checktheline to view the web camera feeds, disposal times, and for facility locations, hours, and directions.
For noxious weeds that are not regulated and not poisonous but still awful, it’s best to put them in yard waste bins or take them to the yard waste section of the transfer station where the plant material will be professionally composted at high temperature. Yard waste info for King County residents and tip for Seattle residents about where to put invasive plants.
If you compost on your own, it might not get hot enough for long enough to destroy seeds and tough roots. You probably shouldn’t put anything in your compost bin that you don’t want growing in your garden. Think morning glory or knotweed.
If you don’t have access to yard waste disposal, another option is to create piles in a place where you can keep an eye on them and where the weeds are not likely to take root (such as on tarps, gravel or hard-packed soil).
Make sure to cover the pile with a tarp to contain the weeds and help them dry out. After the plants have dried out (or turned to mush if they are wet weeds), you will have much less material and can more easily discard the material in the trash, burn it if you have that option, or just keep adding more weeds to the pile as it shrinks. Just don’t use that compost as mulch anywhere else in case there are seeds or surviving roots or fragments.
If you choose this method, make sure to remove any flowering or seeding tops and discard those in the trash. It’s amazing how long-lived some seeds are and you probably don’t want to create a giant pile of weed seeds on your property!
There isn’t any one solution that fits all situations, but the worst thing you can do with weeds is to dump them in a place where you aren’t watching them. Many plants are able to re-grow from root, stem and rhizome pieces, even when they appear to be dead (think of an iris rhizome). Other plants are able to form seeds even after they are pulled (tansy ragwort and thistles come to mind). This creates a long term problem by adding to the seed bank or spreading the weeds to new places with the help of wind, animals or water.
Even though it is tempting to toss your weeds over the fence (out of sight, out of mind), please be a good neighbor and dispose of noxious weeds responsibly!
More information and detailed advice is available in the Noxious Weed Disposal brochure from the Washington State Noxious Weed Control Board. Download from their website or request a copy by contacting our program.