So you’re staring at those ugly patches of crabgrass in your lawn and wondering: will fertilizer kill crabgrass?
Will Fertilizer Kill Crabgrass?
No, regular lawn fertilizer WON’T kill crabgrass. And it might make your crabgrass problem WORSE. Some specialty fertilizers with pre-emergent herbicides can prevent it, but only if you time them perfectly. For existing crabgrass, you need to use a weed killer that works after the weeds have grown out of the ground, or you can just pull the weeds by hand.
I know, I know. That’s probably not what you wanted to hear.
But stick with me. As a professional fertilizer production line manufacturer, I’m about to show you exactly what works (and what doesn’t) when it comes to dealing with crabgrass.
Why Regular Fertilizer Won’t Kill Crabgrass
Think about it this way:
Crabgrass is a grass. Just like your lawn grass.
When you throw down fertilizer, you’re basically feeding BOTH your good grass and the crabgrass. It’s like trying to get rid of weeds in your garden by watering them more.
Doesn’t make sense, right?
In fact, here’s what actually happens when you fertilize a lawn with crabgrass:
- The crabgrass grows faster and stronger
- It spreads more aggressively
- Your lawn looks even worse than before
I learned this the hard way when I first started taking care of my lawn. I thought more fertilizer = better lawn. Boy, was I wrong.
Some Fertilizers That CAN Help (But There’s a Catch)
Now, before you throw away all your fertilizer, here’s something important:
Some fertilizers contain pre-emergent herbicides that can PREVENT crabgrass from sprouting.
The key word here is “prevent.”
These combination products (often called “weed and feed” or “crabgrass preventer plus fertilizer”) work by creating a chemical barrier in the soil. When crabgrass seeds try to germinate, they hit this barrier and die.
Popular examples include:
- Scotts Turf Builder Halts
- GreenView Fairway Formula Spring Fertilizer
- Pennington UltraGreen Crabgrass Preventer
But here’s the catch:
These products ONLY work on seeds that haven’t sprouted yet. If you already see crabgrass in your lawn, these preventers are about as useful as a screen door on a submarine.
The Critical Timing Factor Most People Mess Up
Timing is everything with pre-emergent herbicides.
You need to apply them BEFORE crabgrass seeds germinate. In most areas, that’s when soil temperatures hit 55-60°F for several days straight.
Here’s a pro tip:
Watch for forsythia bushes in your neighborhood. When they bloom bright yellow, that’s nature’s way of telling you it’s time to apply crabgrass preventer.
Miss this window? You’re out of luck for the year.
What Actually Kills Existing Crabgrass
If crabgrass has already invaded your lawn, you need post-emergent herbicides.
These are completely different products designed to kill actively growing crabgrass plants.
Some effective options:
- Products containing quinclorac
- Drive XLR8 herbicide
- Tenacity (mesotrione)
Or you can go old school and pull it out by hand. Just make sure you get the entire root system, or it’ll grow back faster than you can say “lawn disaster.”
The Fertilizer Mistake That Makes Crabgrass Worse
Here’s something most homeowners don’t realize:
Certain fertilizers can actually ENCOURAGE crabgrass growth.
High-nitrogen fertilizers applied in late spring or summer? That’s like rocket fuel for crabgrass.
Phosphorus-heavy fertilizers in spring? Crabgrass loves that stuff.
The worst part:
While you’re inadvertently feeding the crabgrass, your desirable grass might be struggling in the summer heat. So the crabgrass takes over even more of your lawn.
A Smarter Approach to Lawn Care
Instead of asking “will fertilizer kill crabgrass,” here’s what you should be doing:
Step 1: Prevention First
Apply pre-emergent herbicide (with or without fertilizer) in early spring before crabgrass germinates.
Step 2: Spot Treat Problems
Use post-emergent herbicides on any crabgrass that sneaks through.
Step 3: Build a Thick, Healthy Lawn
A dense lawn is your best defense. Crabgrass thrives in thin, weak lawns where it doesn’t have competition.
Step 4: Time Your Fertilizing Right
Feed your lawn when it needs it most – early fall for cool-season grasses, late spring for warm-season grasses.
The Cultural Controls Everyone Ignores
Want to know the secret to keeping crabgrass out long-term?
It’s not about what products you use. It’s about creating conditions where crabgrass can’t thrive:
- Mow high (at least 2.5-3 inches)
- Water deeply but infrequently
- Overseed thin areas in fall
- Fix compacted soil
These simple practices make a bigger difference than any fertilizer or herbicide.
Common Myths About Crabgrass Control
Let me bust some myths I see all the time:
Myth #1: “More fertilizer = less weeds”
Reality: Often the opposite is true, especially with summer fertilizing.
Myth #2: “Weed and feed products solve everything”
Reality: They’re tools, not magic bullets. Timing and lawn health matter more.
Myth #3: “If I kill crabgrass once, it’s gone forever”
Reality: Those seeds can survive in soil for years. It’s an ongoing battle.
The Bottom Line on Fertilizer and Crabgrass
So, will fertilizer kill crabgrass? No, regular fertilizer won’t kill it. Some specialty products with pre-emergent herbicides can prevent it, but only if you time them perfectly. For existing crabgrass, you need either post-emergent herbicides or good old-fashioned elbow grease.
But here’s what really matters:
Focus on building a healthy, thick lawn that naturally resists crabgrass invasion. That’s a much better long-term strategy than constantly fighting weeds with chemicals.
Remember: crabgrass is an opportunist. It shows up where your lawn is weak. Make your lawn strong, and crabgrass won’t stand a chance.
