Will Lawn Fertilizer Kill Weeds

Lawn fertilizer will not kill weeds because it’s designed to feed your grass, not destroy unwanted plants.
 
If you’ve been asking yourself, “will lawn fertilizer kill weeds?” the short answer is no, standard fertilizers simply lack the herbicides needed to target broadleaf invaders like dandelions or clover.
 
So, will lawn fertilizer kill weeds on its own?
 
Not in most cases, though some products combine fertilizer with weed-killing chemicals, and those can do both jobs at once.
 
In this post, we’ll break down why plain lawn fertilizer won’t kill weeds, what happens when you apply it, and how you can actually tackle weeds without harming your turf.
 
Let’s dig into the details so your lawn stays thick and weed-free.
 
 

Why Lawn Fertilizer Won’t Kill Weeds

Lawn fertilizer won’t kill weeds because its primary job is to supply nutrients like nitrogen, phosphorus, and potassium to your grass.
 
Weeds are plants too, and they happily absorb those same nutrients right alongside your turf.
 
So, will lawn fertilizer kill weeds just because it makes grass grow faster?
 
No, faster grass growth doesn’t automatically choke out weeds, and in some cases, fertilizing can even give weeds a boost if your lawn is thin.
 
Here’s why this matters for your yard.
 

1. Fertilizer Feeds Everything, Not Just Grass

When you spread lawn fertilizer, you’re feeding every green plant in the area, including weeds like crabgrass, plantain, and chickweed.
 
Will lawn fertilizer kill weeds by starving them of light or nutrients?
 
Only indirectly, if your grass becomes so thick and healthy that it shades the soil, some weeds might struggle to germinate.
 
But established weeds with deep roots will still thrive on that fertilizer buffet.
 
So, if your goal is weed elimination, plain fertilizer won’t deliver.
 

2. Standard Fertilizer Lacks Herbicides

The reason will lawn fertilizer kill weeds gets a firm “no” is simple chemistry.
 
Regular lawn fertilizer contains only macronutrients, not active weed-killing ingredients like 2,4-D, dicamba, or glyphosate.
 
Without those herbicides, fertilizer has no mechanism to damage weed cell walls or disrupt their growth.
 
It’s like asking if watering your garden will kill aphids, it just doesn’t work that way.
 

3. Fertilizer Can Actually Help Weeds Grow

Here’s a twist: will lawn fertilizer kill weeds or make them worse?
 
If you fertilize a lawn with bare patches, weeds will gladly take those nutrients and fill in the gaps.
 
Weeds like annual bluegrass and purslane love nitrogen-rich soil, so you might see more weeds after fertilizing, not fewer.
 
That’s why experts recommend fixing bare spots and overseeding before you fertilize.
 
 

When Lawn Fertilizer Can Help Control Weeds

Will lawn fertilizer kill weeds if you choose the right product?
 
Yes, but only when you specifically buy a weed-and-feed formula that includes both nutrients and herbicides.
 
These combination products are designed to answer “will lawn fertilizer kill weeds?” with a clear yes, because they attack weeds while feeding your grass.
 
Here’s how to make that work.
 

1. Weed-and-Feed Products Combine Both Jobs

Weed-and-feed fertilizers contain pre-emergent or post-emergent herbicides mixed with standard lawn nutrients.
 
Pre-emergent types stop weed seeds from sprouting, while post-emergent types kill existing weeds after they’ve popped up.
 
So, will lawn fertilizer kill weeds if you use a post-emergent weed-and-feed?
 
Absolutely, the herbicide in that mix targets broadleaf weeds like dandelions, clover, and chickweed on contact.
 
Just read the label carefully to match the product to your weed type.
 

2. Timing Matters for Maximum Weed Control

Even with weed-and-feed, will lawn fertilizer kill weeds only if you apply it at the right time?
 
Yes, timing is critical because herbicides work best when weeds are actively growing.
 
Apply in early spring or fall when temperatures are between 60–85°F, and make sure the soil is slightly moist.
 
If you apply during a drought or heatwave, the weeds won’t absorb the chemicals effectively, and you’ll waste your effort.
 

3. Spot Treatments Work Better Than Blanket Fertilizing

For stubborn or widespread weeds, will lawn fertilizer kill weeds as well as a dedicated spot sprayer?
 
Probably not, because broadleaf herbicides in liquid form are more concentrated and precise.
 
You can use a weed-and-feed for general maintenance, but for big infestations, spot-treat with a herbicide spray first.
 
Then, wait two weeks before fertilizing so the weeds die off and your grass can absorb nutrients without competition.
 
 

What Actually Kills Weeds in Your Lawn

Since lawn fertilizer won’t kill weeds by itself, you need other tactics to get rid of them.
 
Will lawn fertilizer kill weeds ever be enough if you pair it with good lawn care habits?
 
Sometimes, but only when combined with the following steps.
 

1. Use a Dedicated Herbicide for Existing Weeds

A selective broadleaf herbicide is your best bet for killing weeds without harming grass.
 
These sprays target the weed’s root system and leaves while leaving your turf untouched.
 
So, will lawn fertilizer kill weeds if you skip the herbicide?
 
No, you’ll need to apply the herbicide separately, either as a liquid spray or granular spreader application.
 

2. Pull Weeds by Hand for Small Areas

If you only have a few weeds, hand-pulling is effective and instant.
 
Will lawn fertilizer kill weeds that you’ve already pulled?
 
No, but pulling removes the weed entirely, so fertilizer can then help your grass recover and fill in the bare spot.
 
Make sure to remove the entire root, especially for taproot weeds like dandelions.
 

3. Maintain a Dense, Healthy Lawn

The best long-term answer to “will lawn fertilizer kill weeds?” is that a thick lawn crowds them out naturally.
 
Mow high (3–4 inches), water deeply but infrequently, and aerate your soil once a year.
 
When your grass is dense, weeds can’t get enough light or space to establish, so fertilizing becomes your ally, not a weed booster.
 
 

So, Will Lawn Fertilizer Kill Weeds?

Lawn fertilizer will not kill weeds because standard formulas only feed plants, they don’t destroy them.
 
The only way to answer “will lawn fertilizer kill weeds?” with a yes is to use a weed-and-feed product that includes herbicides.
 
So, will lawn fertilizer kill weeds if you apply it alone?
 
No, but when you pair it with hand-pulling, dedicated herbicides, and proper lawn care, you can get a weed-free yard.
 
Keep fertilizing your grass, but don’t expect it to do double duty as a weed killer.
 
With the right approach, your lawn will look lush and healthy all season long.