Smartweed (Polygonum spp.) may have erect or creeping rootstocks. The stem is distinctly jointed, with each swollen joint or node covered by a thin sheath. Leaves are alternate and usually linear to elliptical. Flowers are white, or pink. Smartweed may be emerged or submersed with only the flowers being displayed.

Mechanical Control

Smartweed can be cut down or the roots can be dug up. It will be difficult to control this way because it will regrow from seeds and remaining roots.

Chemical Control

Systemic herbicides, such as Shoreline Defense, will work to kill the root of the plant.

Chemical Application Best Practices

Anytime you use chemicals treat weeds and algae, please keep in mind the following:

  • Treat your pond in sections. Treat only half the pond's surface at a time. During hot weather or when treating heavy growth, it is important to treat no more than 1/4 of your pond at a time and wait the full 14 days before re-applying. This helps lower the risk of fish loss during hot weather or when treating heavy growth.
  • Once the weeds have browned & died, use a weed cutter & rake to remove as much dead material as possible. This prevents an accumulation of dead plant material and muck.
  • Take a proactive approach to pond management. Use PondClear, MuckAway and Pond Dye to keep your pond looking great. For more information, see our article on the Airmax Ecosystem.

Ask an Expert

If you are unable to identify your pond weed(s) using our Weed ID Guide, follow this article to email us a photo.