How To Kill Pampas Grass

That towering plume grass has roots reaching six feet deep, so cutting it down alone won’t finish the job. If you’re searching for how to kill pampas grass, you need a plan that targets the root system, not just the leaves. This guide walks you through every effective method, from digging to chemical control, so you can reclaim your yard for good.

Pampas grass looks pretty in the fall, but it’s a bully. It crowds out native plants, creates a fire hazard, and its razor-sharp leaves can cut you. Once established, it’s a serious fight. But you can win. Here’s the honest truth: you have three main options—digging, smothering, or using herbicides. Each works, but they require different levels of effort.

Why Cutting Alone Fails

You might think a chainsaw or a string trimmer is the answer. It’s not. Cutting the foliage off only removes the visible growth. The crown, which is the thick, woody base of the plant, stays alive underground. And those deep roots, which can reach six feet down, store energy. They will simply push up new shoots in a few weeks. You have to kill the crown and the roots, or you will be doing this again next year.

Also, never burn pampas grass. The fire gets so hot it can damage the soil and spread out of control. It also doesn’t kill the deep roots. You’ll just have a charred mess that regrows. Stick to mechanical or chemical methods.

This is the core of the job. Below, I break down the three most reliable strategies. Choose the one that fits your physical ability, your patience, and your willingness to use chemicals.

Method 1: Digging Out The Root Ball

This is the most physically demanding method, but it’s also the most permanent. No chemicals are needed, and you get the entire plant out of the ground. This is the best option if you have one or two plants and you’re in decent shape.

Here is the step-by-step process:

Cut the foliage back. Use a sharp saw or hedge trimmers to cut the leaves down to about 6 inches above the ground. This gives you access to the crown and removes the sharp blades that can cut your arms.
Loosen the soil. Use a sharp spade or a pickaxe to dig a trench around the base of the plant. Go down at least 18 to 24 inches. You need to cut the lateral roots that spread out from the center.
Rock the crown. Once you’ve dug around the base, use a digging bar or a sturdy shovel to pry the crown loose. This is heavy work. The root ball can weigh over 100 pounds for a mature plant.
Leverage is key. If the crown won’t budge, use a long iron pry bar. Place a block of wood under the bar to use as a fulcrum. This gives you massive leverage to pop the root ball out of the hole.
Remove the debris. Once the root ball is out, you must dispose of it properly. Do not compost it. The seeds and roots can survive. Put it in the trash or let it dry out completely on a concrete slab before burning (where legal).
Check for stragglers. After you pull the main ball, there will be broken roots left in the soil. Dig through the dirt and remove as many as you can find. Any piece larger than a finger can regrow.

This method takes about 30 to 60 minutes per plant. It’s a workout, but it’s done. You don’t have to wait for weeks for chemicals to work.

Method 2: Smothering The Grass

If you can’t dig, you can suffocate it. This method takes longer, but it requires almost no physical effort. It works by blocking all light and oxygen from the plant, which eventually kills the crown and roots. It is best for large patches or for plants growing in awkward spots.

Here is how to smother pampas grass:

Cut the grass down as low as possible. Use a mower or a saw. The lower you get it, the faster it will die.
Cover the area. Use a thick, black plastic tarp or a heavy-duty landscape fabric. You need something that blocks 100% of sunlight. Do not use clear plastic, as it lets light through.
Weigh it down. The grass will try to push up. Place heavy rocks, bricks, or cinder blocks on the edges and the center of the tarp. You don’t want any gaps.
Wait. This is the hard part. You need to leave the tarp on for at least one full growing season. Six months is the minimum, but a full year is better. The crown needs to starve completely.
Check underneath. After a few months, lift a corner and look. If the crown is still white and firm, it’s not dead yet. If it’s mushy, brown, and falling apart, you’ve won.

The downside here is the wait. You’ll have a black tarp in your yard for a long time. But it is very effective and uses zero chemicals.

Method 3: Herbicide Application

Using a systemic herbicide is the most effective way to kill a large infestation. The chemical is absorbed by the leaves and travels down to the roots, killing the entire plant. This is the best option if you have a fence line full of pampas grass or if you can’t dig.

Here is the professional approach to spraying:

Timing is everything. Spray in late summer or early fall. This is when the plant is pulling energy down into its roots for the winter. The herbicide goes right along with that energy flow.
Do not cut first. For this method, you need the leaves. The more leaf surface you have, the more herbicide the plant absorbs. Cutting it down first reduces the effectiveness.
Use the right chemical. Look for a product containing glyphosate (like Roundup) or imazapyr. Glyphosate is a non-selective herbicide that kills everything it touches. Imazapyr is a soil-active herbicide that works well on grasses but can linger in the soil.
Mix it strong. For tough perennial grasses, you need a higher concentration. Mix the herbicide at a rate of 2% to 3% solution. Add a non-ionic surfactant (a few drops of dish soap works) to help the chemical stick to the waxy leaves.
Spray thoroughly. Coat every leaf until it is wet but not dripping. Focus on the upper and lower surfaces of the blades.
Wait two weeks. You should see yellowing and browning. If you see new green growth, wait another two weeks and spray again.
Remove the dead material. Once the plant is completely brown and crispy, usually 4 to 6 weeks after spraying, you can cut it down. The roots will be dead, so you can also dig out the crown easily if you want it gone physically.

Important warning: Glyphosate is non-selective. If it drifts onto your lawn or your prized roses, it will kill them. Spray on a calm day with no wind. Use a shield made of cardboard to protect nearby plants.

Chemical Application Tips

If you are dealing with a huge area, a pump sprayer is better than a trigger bottle. Also, check the weather. If rain is expected within 6 hours, the chemical will wash off. You need a dry window. Also, wear protective gear. Wear long sleeves, pants, gloves, and safety glasses. The grass blades are sharp, and the chemical is toxic.

What To Do After The Grass Dies

Killing the plant is only half the battle. You need to deal with the aftermath. If you used the digging method, you already have a hole. If you used chemicals or smothering, you have a dead stump.

Here is what to do next:

Fill the hole. If you dug the plant out, fill the hole with topsoil. Tamp it down firmly to prevent sinking.
Plant a replacement. Pampas grass leaves a big gap. Plant a native ornamental grass like switchgrass or little bluestem. These don’t have the invasive tendencies and provide similar visual appeal.
Watch for seedlings. Pampas grass produces thousands of seeds. Even after you kill the mother plant, seeds in the soil will germinate. Pull up any small seedlings you see immediately. They are easy to pull when young.
Consider a barrier. If you are planting new grass, install a root barrier. This is a plastic sheet buried vertically in the soil that prevents roots from spreading.

Preventing Regrowth

You don’t want to do this again. Here are a few habits to prevent a return of pampas grass:

Mow regularly. If you have a lawn, mowing prevents pampas grass from establishing. It can’t survive repeated cutting.
Mulch flower beds. A thick layer of mulch (3 inches) prevents seeds from germinating.
Use pre-emergent herbicide. In the spring, apply a pre-emergent herbicide to areas where you had pampas grass. This stops seeds from sprouting.
Inspect your property. Walk your fence line and property borders a few times a year. Look for the distinctive tall plume and sharp leaves. Kill it when it’s small, not when it’s a giant.

Frequently Asked Questions

Here are some common questions people have when they are trying to get rid of this stubborn plant.

Can I use vinegar to kill pampas grass?

Household vinegar is not strong enough. Horticultural vinegar (20% acetic acid) will burn the leaves, but it doesn’t kill the deep roots. The grass will regrow from the crown. It’s a waste of time for established plants.

Is it better to cut pampas grass before spraying?

No. You want maximum leaf surface area to absorb the herbicide. Cutting it down reduces the amount of chemical that reaches the roots. Spray it while it is tall and leafy.

How long does it take for pampas grass to die after spraying?

You will see yellowing within 7 to 14 days. Complete death takes 4 to 6 weeks. Be patient. Do not cut it down too early, or you might interrupt the chemical’s path to the roots.

Can I burn pampas grass to get rid of it?

It is not recommended. The fire is intense and can spread. It also does not kill the deep roots. The crown will survive and resprout. It’s a dangerous and ineffective method.

What is the best time of year to kill pampas grass?

For digging, any time the ground is not frozen works. For herbicides, late summer to early fall is best. This is when the plant is storing energy in its roots, making it more susceptible to systemic chemicals.

Final Thoughts On Eradication

Getting rid of pampas grass is a chore, but it’s a manageable one. You have to be persistent. The physical digging method is immediate but tough. The smothering method is easy but slow. The chemical method is effective but requires care and patience.

Pick the method that suits your situation. If you have one plant, dig it out. If you have a dozen, spray them. If you can’t lift a shovel, smother it. Whatever you choose, stay on top of it. Check the area for regrowth every few weeks. If you see a green shoot, pull it or spot-spray it immediately. Do not let it get a foothold again.

Once the pampas grass is gone, you’ll wonder why you waited so long. You’ll have more space, a safer yard, and you won’t have to dodge those razor-sharp leaves anymore. The work is worth it. Just remember to be thorough with the roots, and you will be successful.