It’s Not Too Late For Perennial Treatments!


The temperatures are dropping, the aspens are turning yellow, and it seems like summer flew by in the blink of an eye. How is it almost October already?!

If you think it’s too late in the season to effectively spray your weeds, think again! It’s still a great time to spray perennial plants and see results next spring.

Perennial Plants

What’s a perennial? 

Perennials plants are plants that live two years or more—essential year after year. Invasive perennials are pesky plants to get rid of because they keep popping up each spring. Many perennials spread by their roots. Even if you pull the invasive plant or cut off the flowering parts, it will (or could) still come back the following year.

So, Why is the Fall a Good Time to Treat Perennials? 

At this time of year perennial broadleaf weeds prepare for our harsh winters by building up carbohydrate reserves for the months ahead. They store this energy in their roots which means that invasive perennials are currently moving their energy downward in their large, central taproots. It’s the perfect time to use an herbicide that is otherwise ineffective in the summer because it would only kill the stem and not the entire plant.

Use Systemic Herbicides to Treat Perennials

Systemic herbicides are a great option if you have invasive perennials on your land. Unlike contact herbicides which kill the plant material that they initially touch, systemic herbicides are absorbed and move throughout plants. The effect may not be apparent for up to two weeks, but they can effectively kill plants with extensive root systems. As you can see, a systemic herbicide would be an ideal treatment for invasive perennials that are currently moving energy from the rest of the plant down to their extensive root system. When you treat invasive perennials in the fall, you can completely kill the plant and see lasting results.

What Are Some Examples of Invasive Perennials in Teton County?

  • Canada Thistle
  • Damesrocket
  • Spotted Knapweed
  • Purple Loosestrife
  • Field Bindweed
  • Baby's Breath
  • Absinth Wormwood
  • Perennial Pepperweed
  • Oxeye Daisy
  • Hoary Cress (whitetop)
  • Rush Skeletonweed
  • Sulfur Cinquefoil 
  • Tall Buttercup
  • Yellow Toadflax
  • Meadow/Yellow Hawkweed
  • Russian Knapweed
  • Saltcedar

If you’re unsure whether or not a plant is an invasive perennial, fill out our Invasive Plant Identification Form and/or request a free in-person site visit with TCWP staff through our Invasive Plant Consultation Form

Herbicide Sales End September 30th!

Don’t wait to treat your invasive perennials! Come to our district office at 7575 South Highway 89 to purchase what you need while perennial treatments are still effective. Our office is open Tuesday through Friday from 7:30am to 4:30pm until our off-season hours start on October 15th.