How To Stop Perennial Weeds From Coming Back

While some weeds are annuals that blow into your yard each spring, others patiently wait out winter. The trouble with perennial weeds is that you may not know they’re yearly until they appear in the same spot next spring. You’re not alone if you’ve ever wondered how to stop perennial weeds from coming back.

You can stop perennial weeds from returning by covering them with cardboard or plastic for 4 to 8 weeks. Doing so will deprive them of oxygen, water, and sunlight, which takes weeks, but ensures they won’t return. Otherwise, you can kill perennial weeds using distilled white vinegar, boiling water, or an herbicide that contains glyphosate.

You can also manually remove them, but that’s only effective if you fully remove the root system. Weeds can grow back even from tiny root remnants, so you must take out every piece of the plant. Follow along as we explore how to stop perennial weeds from coming back every year.

Do The Same Weeds Come Back Every Year?

Perennial weeds come back every year if you don’t eradicate them. However, other weeds that pop up in your yard each year are likely annuals that drop seeds that the wind carries from yard to yard and field to field. That’s why many gardens have a mixture of annual and perennial weeds. Common annual varieties include purslane, crabgrass, pigweed, foxtail, and ragweed. Dandelions, white clover, field bindweed, and quackgrass are typical perennial weeds.

How Do You Get Rid Of Perennial Weeds?

1. Manually

Many people want to stop perennial weeds from coming back without using chemicals. The best option is to dig up the weeds and destroy the root system. Pulling them by hand isn’t always effective, as roots often linger in the earth. That’s why you must dig up the weeds, expose the root system, and remove it to ensure they don’t come back. The trick is to wet the ground so you can more easily penetrate the soil deep enough to reach the roots.

Dig a hole that’s wider than what you see of the weeds above ground, as root networks expand horizontally. Once you reach the roots, remove them. If that’s not possible, chop the roots into pieces and manually remove them to ensure they don’t grow back. You may need to repeatedly cut the remaining pieces over a few weeks until the weeds stop coming back.

2. Smothering

Everyone knows that most plants rely on plenty of sunlight, water, and oxygen, and that includes weeds. You can use that to your advantage and deprive them of these necessities to ensure they don’t come back. To smother perennial weeds, cover the above-ground weeds and the below-ground root system to block out sun and water. Use plastic tarps and sandbags, or you can also use cardboard.

Lay it over the weeds and let it extend a few feet past the weeds on either side, so there is no new growth popping up a few feet away. Place a weighted sandbag on each corner of the tarp to ensure the wind doesn’t blow it away. Add more layers of tarp and cardboard if needed, and wait roughly 4 to 8 weeks to fully eradicate the weeds. Don’t lift the tarp in the first few weeks to check, since the process takes a while.

3. Herbicides

Herbicides, much like pesticides, are controversial given their potential to harm the environment, wildlife and people. Some people battle perennial and annual weeds all spring and summer and turn to commercial herbicides to stop them from coming back. Before you buy an herbicide, look for a product that contain triclopyr or glyphosate, as they offer the best results. Whichever product you choose, closely follow the instructions to ensure the best results, or else the weeds may linger.

Many brands recommend spraying the weeds when they are lush and somewhat mature to ensure the weeds will absorb the chemicals and pull the poison downward into the root system, and then die. That’s the best-case scenario, but it isn’t always that easy, and you may need to expose the roots and spray them directly. Systemic herbicides are the best option if you want to attack the roots without digging.

4. Boiling Water

You can also use boiling water to permanently kill weeds, whether they’re annuals or perennials. This is a much safer option than using commercial herbicides, as no chemicals are involved. You can either expose the roots and douse them with boiling water or pour boiling water onto the above-ground weed. With the latter option, your best bet is to pour boiling water directly into the middle of the weed.

That way, you’ll damage the leaves and stems, and the hot water will seep into the root system. You can also pour boiling water onto the weeds sprouting out of the cracks in your driveway and sidewalks. If dousing the weeds’ leaves doesn’t work, you can expose the roots using a shovel and pour scalding water directly onto them. This is the best option if you don’t mind digging big holes in your yard and garden. 

5. Mulch

Mulch offers so many benefits, and weed suppression is easily among the most popular. It doesn’t permanently kill weeds and stop them from coming back, but applying mulch should be one of the last steps you take to stop perennial weeds from returning. The key is to manually remove as many weeds as possible before filling your soil bed with mulch.

You can also treat the remaining weeds with a post-emergent herbicide to kill them before applying mulch. You can also use it before laying mulch to ensure new seeds don’t sprout afterward. Look for mulch with plenty of organic materials, like straw and shredded hardwood chips. Ideally, you should apply 2” to 3” of mulch to keep weeds at bay and maximize moisture retention for your favorite plants.

Does Vinegar Permanently Kill Weeds?

Vinegar doesn’t permanently kill weeds in most cases, unless they’re young and weak. However, you will at least notice some damage shortly after spraying weeds with vinegar, even if they don’t outright die. That’s because vinegar contains acetic acid, which damages a plant’s coating and often makes it look scorched. This fools many people into thinking the weeds are dead, but they're not.

The problem is that it doesn’t matter how much you damage the above-ground leaves. As long as the root system is intact, weeds can easily emerge again. However, you’ll have much better luck if you expose the weeds’ roots and directly spray them with distilled white vinegar. Otherwise, you can repeatedly kill the above-ground leaves until they stop coming back, but that can take months.

Summing It Up

The best way to stop perennial weeds from coming back is to manually destroy and remove the root system. Otherwise, you can cover the weeds and surrounding ground with tarps, cardboard, and sandbags to smother them until they die. Commercial herbicides are also quite effective, but vinegar and boiling water are better options if you want to be environmentally friendly.

Related Guides:

• Why Do I Still Have Weeds In My Yard?
• How To Prevent Weeds In The Spring