How to Kill Weeds in Grass: 5 Methods for a Weed-Free Lawn

The importance of a weed-free lawn goes far beyond impressing your neighbors—though it certainly helps. Everything from persistent crabgrass to fluffy dandelions compete for the precious nutrients your lawn needs to simply live its life. Learning how to kill weeds in your grass calls for a mix of comprehensive lawn care, natural weed repellent, and good old-fashioned mechanical weed removal.

Why Do I Have Weeds in My Lawn?

Even the most careful homeowners end up with unwanted patches of weeds in their grass. Seeds travel by wind, on our shoes, and even in the fur of your golden retriever. Grass seed mixtures can also hide a few stowaways, leading to issues if you overseed your lawn once a year.

In other words, the occasional weed is unavoidable. However, the difference between a handful of dandelions and a yard of quackgrass often comes down to the state of your lawn itself. Poor drainage, unbalanced nutrients, or thick thatch can create a happy home for weeds to spread.

How to Prep for DIY Weed Control

It's important to start with the age-old question: Is it a plant or a weed? Technically, the term is subjective. For example, in the case of ground cover plants, species consider weeds in one yard to be beneficial in another. Identifying the type of weed and whether it's helping your lawn's ecosystem is an important first step.

Identifying Weeds in Your Grass

The species of plant lurking in your grass also determines when you should remove weeds and which weed-killing method works best. The simplest way to classify weeds is by getting to know their average life cycles. 

For example, annual weeds complete a full life cycle in a year or less. That means they germinate, grow to adulthood, flower, produce seeds, and die all before the year is up. Biennials last up to two seasons while perennial varieties can come back time and time again, requiring regular treatments during their initial germination period.

Chemical vs. Natural Ways to Kill Weeds

Chemical herbicides may offer a faster way to kill weeds in your grass, but they come with some major caveats. According to the National Pesticide Information Center, glyphosate, one of the most common active ingredients in a majority of brand-name herbicides, can cause eye, nose, throat, and skin irritation. They can also harm wildlife that’s critical to your garden’s ecosystem, like butterflies, bees, and more. 

Additionally, it's important to consider why the weeds chose to stick around in your lawn. Opting for natural ways to kill weeds in your grass ensures the long-term resilience of your overall landscape. 

How to Kill Weeds in Your Grass

Determining how to kill weeds depends on your lawn's health, the type of weed, and the depth of its roots. While mechanical removal—such as yanking them up by hand—is best in the short term, pre-emergent weed killer or integrative lawn care may be necessary to keep persistent weeds away season after season.

1. Pull Them Up by the Roots

A tried-and-true method of learning how to kill weeds in your grass is simply pulling weeds up by the roots. Whether you use your hands, a weeding fork, or a stand-up weeder, it's crucial to get to the base of the roots to keep the weed from growing back. 

• Make sure the ground is moist. If it’s too dry, pour a small amount of water around the weeds and let it soak into the soil for a few minutes. If it’s too saturated, wait until the area dries out to remove the weeds.

• Make sure the soil isn’t too firm. Use a rake to loosen any compacted soil around the plant.

• Firmly grab the base of the weed and gently pull until you’ve removed the entire plant. If the process sounds too difficult or getting the weed up is presenting a challenge, grab garden claws or a trowel to make the task easier.

Keep in mind that this does not work for all weed types. For instance, if you need to get rid of quack grass, use a weed killer instead. 

2. Apply a Homemade Weed Killer

Homemade weed killers such as white vinegar, dish soap, salt, and even boiling water, can also wipe out weeds down to the root. On the other hand, no homemade weed killer acts as a selective herbicide. All of these remedies will keep the surrounding grass as well, requiring some TLC for the patch of grass after the fact. Here are some methods for using a DIY weed killer.

1. Combine four-parts white vinegar and one-part water and spray the solution on the leaves, stem, and the roots of the weed.

2. Combine three parts vinegar and one part dish soap with a tablespoon of salt. Spray on the plant and the remaining roots.

3. Carefully pour boiling water either on a fully grown weed or the remaining roots after mechanical removal.

4. Allow the solution or water to sit undisturbed for several hours before attempting to remove the weed. 

3. Nurture a Lush Lawn

When weeds pop up again and again in your grass, it's likely a sign of poor lawn health. Weeds often thrive in soil with low nutrients, poor drainage, or areas that are highly compacted. Others weeds hold when the grass itself begins to fail, leaving space for them to spread out and fill in the gaps. 

Test Your Soil

Perform soil nutrient and soil pH test to ensure your lawn contains the right balance of nitrogen, phosphorus, and potassium as well as the right pH to absorb ongoing nutrients. You can also Order a soil perc test to analyze how well your soil drains moisture. Keep an eye out for areas of pooling water, signs of mold, or pest problems related to poor drainage.

Mow with Consistency

Cut your lawn on a regular schedule and at a height that encourages healthy growth. On average, never cut more than one-third of the grass blade's height.

Strengthen Each Season

Follow a set lawn maintenance schedule that includes proper fertilization, aeration, and thatch removal depending on where you live and the variety of grass in your lawn.

4. Apply a Pre-Emergent Treatment

Pre-emergent weed control products are some of the best solutions for killing weeds in your lawn without harming the grass itself. These treatments tackle the seeds before they germinate and begin growing in the spring and fall. 

Corn Gluten

Corn gluten meal prevents many types of undesired plants from growing, like crabgrass, dandelions, chickweed seeds, and more. 

1. Generously scatter the corn gluten meal over the soil, using roughly 10 pounds per 500 square feet. 

2. Lightly water your yard so the corn gluten meal sticks to the weed seeds.

3. Repeat the process in both early spring and summer to handle different types of weeds. 

Mulch

Mulch can also smother specific weed-prone areas from producing weeds, such as flower beds beside your lawn. Mulch keeps soil and plant roots cool, prevents frost accumulation in winter, and helps beautifully tie together your entire garden bed or landscape.

1. Buy shredded or chipped bark from your local home improvement store. 

2. Apply a 2- to 3-inch layer of mulch around your plants to prevent sunlight from getting through to the weeds, leaving a small gap at the base of the plants. (If you put the mulch too close, it can cause the plant to retain too much moisture and rot.)

Landscape Fabric

If you're laying down new grass seed or planting a fresh garden bed beside your lawn, landscape fabric can keep weeds from germinating and taking root. Buy a high-quality fabric and avoid plastic products since plastic won’t allow moisture to reach the plants that need it. 

1. Pull up any weeds before laying down the fabric. 

2. Secure the sheet with landscape fabric staples. Use one staple for every 10 feet of fabric.

3. Plant any flowers or grasses you want in your yard. For flowers that have already bloomed, carefully cut out the fabric around the base of the plant.

4. Place mulch over the entire sheet of fabric. 

Synthetic Pre-Emergents

Chemical pre-emergents may not check the eco-friendly box, but some target ultra-specific weeds before they take off. You will find them in either granular or liquid form in both selective and non-selective combinations.

1. Always wear protective gloves, goggles, and a mask when applying chemical herbicides. 

2. Follow the instructions on the herbicide container for the application's timing, distribution, and follow-up steps.

3. In most cases, you will need to keep your grass clear for at least 24 hours.

5. Remove Overgrown Weeds With Sheet Mulching

If you're comfortable reseeding your lawn from scratch, sheet mulching is a natural process to reset your soil. The process is time and labor-intensive, but it is a way to skip the broad-spectrum herbicides.

1. Remove the largest, most overgrown weeds as well as all invasive species with a stand-up weeding tool.

2. Mow your lawn and the weeds to the lowest setting possible.  

3. Water the area thoroughly to reach one-and-a-half inches into the ground.

4. Lay down a barrier of either newspaper or cardboard, removing the areas that surround trees and shrubs.

5. Cover the barrier with a layer of compost and about six inches of organic mulch.

6. Water the area once more and then leave the two layers to sit for between four and six months.

How to Prevent Weeds from Coming Back

The occasional tuft of bluegrass or pesky dandelion is inevitable, but preventing widespread weeds is the best way to limit endless upkeep. Comprehensive lawn care, possibly with the experienced eye of a professional landscaper, is the most likely way to prevent weeds from thriving. 

Keep these general tips in mind to keep weeds from returning next season:

• Build a consistent lawn fertilization schedule to avoid nutrient deficiencies.

• Review the "weed seed percentage" on your bag of grass seed when overseeding or planting new turf.

• Know the signs of poor lawn drainage and who to call to treat drainage problems.

• Create weed barriers, such as landscape fabric, between your lawns and garden beds to prevent weeds from spreading.

• When you find a weed, remove the entire root and treat the area to kill the remaining root caps when necessary.

DIY vs. Hiring a Pro

Keeping up with weeds in your grass is certainly a DIYable task that you can learn and perfect. However, if there is an underlying issue welcoming the weeds to your yard, hiring an experienced local lawn care team can save you a lot of time. Not only can a landscaper manage seasonal lawn care, but they can remove weeds in ways that keep them from coming back the first time.

On average, the cost of lawn care ranges between $30 and $70 an hour, or between $35 and $400 per visit. Comparatively, DIY weed control treatments cost between $15 and $40 per quart, not including the cost of tools.