Once upon a time, some business-savvy company took note that homeowners were spreading weed killer and fertilizer at roughly the same time every year.
Upon seeing this trend, the company thought, “What if we combine weed killer and lawn fertilizer into a single product?”
And so it was that weed and feed was born.
Today, this product exists under various names by several companies, and as either pre-emergent or post-emergent formulas.
But with so many other types of weed killer out there, it’s important to look at how quickly (and how well) weed and feed takes to work.
How Long Do Weed And Feed Take To Work?
While the exact numbers vary from one brand to another, you’ll usually begin to see some results in about a week.
Under the right conditions, it takes 2 to 3 weeks to rid all visible weeds.
Post-Emergent Formulas
Post-emergent formulas are the “kill it now” version of weed and feed.
The purpose of these formulas is to kill visible weeds while still feeding your lawn.
They’re best applied in late summer to early autumn when the weeds haven’t yet gone to seed.
Post-emergent weed and feed will only work on weeds that are actively growing.
Thus, you should apply it a few days after mowing your lawn. In this way, you will catch the weeds when they overcome the shock and begin to grow again.
The fertilizer will be the faster-acting ingredient. You’ll begin to see a healthier lawn and the first signs of weed death in about 5 to 7 days after application.
Once applied, it will usually take 2 to 3 weeks to kill all visible weeds.
Pre-Emergent Formulas
The design of this formula type is to kill weeds as they germinate.
Unlike post-emergent formulas, pre-emergent weed and feed will remain active for 6 to 8 weeks. Your lawn may need reapplication in the spring.
It has a more negligible effect against established weeds but is highly effective against germinating weeds.
The kill time can vary from one brand to another. But they generally work somewhere between seed germination and sprout emergence from the soil surface.
Depending on the types of weeds you’re facing, you may need to give two applications to catch any late germinations.
The Truth About Seeds
When dealing with crabgrass or some broadleaf weeds, it’s important to remember the longevity of their seeds.
Some weed seeds can spring up several years after landing in the soil.
As a result, you may not see weeds completely disappear for five or six years.
This doesn’t mean that your weed and feed aren’t working. Both pre-emergent and post-emergent formulas work on germinated plants.
Additionally, the effectiveness of your weed and feed will depend on many factors, most of which you have some control over.
Tips For Getting The Best Results
As mentioned, weed and feed isn’t a one-and-done product and will have excellent results when used correctly.
Take a few simple rules into account when applying either formula type:
- The product works best when used in 60° to 90° degree Fahrenheit temperatures.
- Use pre-emergent formulas in early spring and post-emergent in late summer to early fall.
- Early morning applications work best, as the lawn should be slightly damp but not wet.
- Or, you can lightly sprinkle the lawn with water to apply later in the day.
- It is best to wait a few days after mowing. The shock may cause existing weeds to go dormant, reducing the effectiveness of weed and feed.
- Use a lawn spreader when applying the product to ensure even distribution.
- After applying, wait at least 24 hours before watering to avoid washing away any unabsorbed weed and feed.
- Wait 48 hours before mowing to ensure the fertilizer doesn’t shift unevenly or accidentally get into garden plants.
Don’t expect a miracle when you add your first dose of weed and feed.
Pre-emergent formulas can help reduce or possibly halt weeds early on. But it will take years of applications to make your lawn truly weed-free.
Likewise, post-emergent formulas can kill your existing weeds but won’t affect seeds. You should always apply them before the weeds can drop any seeds.
Signs That It’s Working
Finally, there are several ways to tell if your weed and feed are effective.
The exact times can vary from one brand to another. Also, pre-emergent formulas will only prove they’re working when you don’t see new weeds sprouting.
- First 24 Hours: It takes about a day for weed and feed to absorb fully, so you’re likely to see no results before this period is up.
- First Week: The fertilizer will work faster than the herbicides. You’ll begin to see the grass growing greener, thicker, and faster at some point in the first 1 to 7 days.
- Days 5 to 7: You’ll begin to notice the weeds gaining a yellow tinge and starting to wilt.
- Days 14 to 21: Crabgrass and other thin-leaf weeds will have wilted and turned brown, making them easy to remove. Broadleaf weeds will begin dying.
- Day 30: All but the hardiest broadleaf weeds are now dead and can be removed, while the grass is a lush green and denser than before.