Fall Post-Emergent Herbicide Application… Is it worth my time?
Fall is rapidly approaching and depending where you live, it may feel like it’s here. For anyone located in the south, where freezing temperatures are rare and snow is more rare, you may have applied, or soon will apply, a second pre-emergent herbicide to prevent unwanted weeds. If that applies to you, please reference our lawn care guide for the south to view product recommendations and general application timing.
The rest of us...
Winter, for most of the country, brings freezing temperatures which may kill some of your unwanted weeds. For a more select part of the country (north), winter brings snow which covers your lawn with a white blanket, keeping unwanted weeds out of sight. Naturally, it could be common for someone to become complacent and think, “I’ll worry about this next year”.
For anyone who is following a lawn maintenance plan and applied a spring pre-emergent herbicide and/or early summer post-emergent herbicide, you will have less weeds than someone who hasn’t treated their lawn throughout the growing season. Nevertheless, chances are even if you have been actively taking care of your lawn throughout spring and summer, you will see that some weeds have emerged.
So about those weeds... What should I do about them?
Apply a selective post-emergent herbicide to control unwanted weeds.
Different species of weeds produce different number of seeds, but typically each individual weed can produce thousands of seeds. Each of those seeds can lay dormant in your lawn for many years waiting for the perfect conditions to germinate. Unlike grass seeds, which require a tremendous amount of care to germinate, weed seeds can tolerate and survive in unfavorable conditions.
What herbicide do you recommend?
The herbicide depends on what type(s) of weed(s) are invading your lawn. In another blog, I covered herbicides that control post-emergent crabgrass. If you have crabgrass, please visit So you have crabgrass... now what? In addition, the herbicide recommendation will depend on what type of grass species make up your lawn. We offer many selective post-emergent herbicides so if you feel the two below won’t control your specific issue, please contact us so we can make a recommendation.
North & Transition
Common grass species: Kentucky Bluegrass, Perennial Ryegrass, Tall & Fine Fescue
Recommendation: Prime Source (Select Source) Triad TZ Select
Four active ingredients, with two modes of action, provide dependable post-emergent weed control of some of the toughest annual and perennial broadleaf weeds in turfgrass.
Visible results (yellowing and drooping of plant) can be noticed as early as a few hours after application and plant death can occur within 10 to 14 days.
Great option for a wide variety of use sites including residential lawns, athletic fields, golf courses, parks and many more.
Low use rates: 1.2 oz – 1.5 oz / 1,000 square feet
Rain fast within 3 hours
South & Transition
Common grass species: Bermudagrass, Centipedegrass, St. Augustinegrass & Zoysiagrass
Recommendation: Quali-Pro Fahrenheit™
Two active ingredients, with two modes of action, provide superior broad-spectrum post-emergent weed control spring through fall of over 100 broadleaf and grassy weeds
Visible results in 7-10 days
Dependable fall season broadleaf and grassy weed clean up; proven results in temperatures as low as 50°F
Offers a wide variety of use sites including residential and commercial lawns, golf courses, sports fields, parks, municipalities and sod farms.
Provides easy-to-use mixing ratios with the addition of measuring device: 6 oz (one bottle) / acre or 4 grams / 1,000 square feet
As always, reference the market label of the specific product to read the full list of restrictions, tolerant grass species and susceptible grass species.