Will Weed Killer Kill Blackberry Bushes

Weed killer can kill blackberry bushes, but the results you get depend heavily on which product you use and how you apply it.
 
Blackberry bushes are notoriously tough perennial plants with deep, aggressive root systems.
 
Because of that, a single spray of a weak herbicide often just burns the leaves while the roots survive underground and send up new canes a few weeks later.
 
But if you choose the right weed killer and apply it at the right time, you can absolutely kill blackberry bushes for good.
 
If you’ve been asking yourself “will weed killer kill blackberry bushes,” you’re in the right place.
 
In this post, we’ll look at whether weed killer kills blackberry bushes, which types actually work, how to apply them properly, and what mistakes to avoid so the blackberries don’t come roaring back.
 
Let’s dig in.
 

Will Weed Killer Kill Blackberry Bushes?

Yes, weed killer will kill blackberry bushes, but only the right kind of weed killer.
 
Here’s what you need to know about how it works:

1. It Has to Be a Systemic Herbicide

Contact weed killers only kill the parts of the plant they touch.
 
That means the leaves die, but the roots stay alive and the blackberry bush regrows.
 
A systemic weed killer is what actually kills blackberry bushes because it gets absorbed through the leaves and travels all the way down into the root system.
 
Glyphosate and triclopyr are the two most effective active ingredients for this job.
 

2. The Roots Are the Real Target

Blackberry bushes spread through rhizomes and deep roots, so killing the top growth does almost nothing.
 
The weed killer has to reach those roots or the plant will bounce back stronger than before.
 
That’s why systemic formulas that move through the plant’s vascular system are the only ones that truly kill blackberry bushes.
 

3. Timing Makes or Breaks the Process

Weed killer kills blackberry bushes best when the plant is actively growing and sending energy to its roots.
 
Late summer to early fall is ideal because the plant is pulling nutrients downward, which helps the herbicide travel straight to the root system.
 
Spraying in the middle of a drought or during dormancy usually gives poor results.
 

Which Weed Killers Kill Blackberry Bushes Best?

Not all weed killers are created equal, so let’s break down which ones will kill blackberry bushes effectively.
 

1. Glyphosate-Based Weed Killers

Glyphosate is one of the most reliable options for killing blackberry bushes.
 
It’s systemic, non-selective, and moves down into the roots after absorption.
 
You’ll typically need a concentrated formula rather than a ready-to-use spray for tough blackberry bushes.
 
Keep in mind that glyphosate kills everything it touches, so protect nearby plants.
 

2. Triclopyr-Based Weed Killers

Triclopyr is another heavy hitter that kills blackberry bushes, especially woody brush like brambles.
 
It’s often sold as a brush killer and works well as a foliar spray or a cut-stump treatment.
 
Many gardeners find triclopyr more effective than glyphosate on blackberry bushes because it targets woody plants specifically.
 

3. Crossbow and Similar Brush Killers

Products like Crossbow combine triclopyr and 2,4-D, which makes them powerful against blackberry bushes.
 
These are formulated for tough brush and woody weeds, so they’re a strong choice when you want to kill blackberry bushes permanently.
 
Just follow the label carefully since these are potent chemicals.
 

How to Apply Weed Killer to Kill Blackberry Bushes

Knowing that weed killer kills blackberry bushes is one thing, but applying it correctly is what gets results.
 

1. Spray the Leaves Thoroughly

Foliar spraying works well when blackberry bushes are actively growing.
 
Coat the leaves evenly, but don’t soak them to the point of dripping.
 
The plant needs to absorb the weed killer through its leaves for it to reach the roots and kill the bush.
 

2. Try the Cut-Stump Method

For larger blackberry bushes, cut the canes down to a few inches above the ground and paint the weed killer directly onto the fresh cuts.
 
This method kills blackberry bushes quickly because the herbicide goes straight into the stump and down to the roots.
 
It’s also more targeted, which reduces damage to nearby plants.
 

3. Repeat the Treatment

Blackberry bushes are stubborn, so one application often isn’t enough to kill them completely.
 
Plan on retreating any regrowth a few weeks later to finish off surviving roots.
 
Consistency is what finally kills blackberry bushes for good.
 

So, Will Weed Killer Kill Blackberry Bushes?

Weed killer will kill blackberry bushes as long as you use a systemic herbicide like glyphosate or triclopyr and apply it correctly.
 
Contact sprays won’t do the job because they leave the roots alive.
 
Time your application for late summer or early fall, spray or cut-stump the canes, and retreat any regrowth.
 
Do that and the weed killer will kill blackberry bushes instead of just setting them back.