Does Mowing Weeds Kill Them? Here’s What You Should Know

This site is reader-supported and I earn commissions if you purchase products from retailers after clicking on a link from this site. As an Amazon Associate, I’ll earn from qualifying purchases.

Having a lawn full of weeds can be a complete disaster. Mowing over them seems like the logical solution since you’ll cut all of the weeds down to their stems, but it might not be the best solution. Sure, you won’t have to deal with their unsightly appearance, but there’s a right and a wrong time to mow them.

Mowing weeds doesn’t kill them, but if you mow them before they drop seeds, you can stop them from reproducing. Set your lawn mower to about two inches high, mow the weeds, then remove them from their roots. Letting the weeds grow too big will produce seeds, sprouting wherever you mow and mulch.

In this post, we’ll show you when it’s okay to mow your weeds and when you should steer clear from them. We’ll also talk about how you can get rid of weeds before mowing, long-term prevention methods, and tips to cut through a dense weed-filled lawn.

Is It OK to Mow Over Weeds?

Mowing weeds is often the quickest way to get them out of the way. Out of sight, out of mind isn’t a saying that applies to most weeds, though. Even if they’re cut low to the ground, they can grow back and reproduce more weeds down the road (or lawn, for that matter).

Here’s what you should do if you’re mowing weeds with a lawnmower:

Mow Weeds Before They Drop Seeds

According to Stable Management, you should always mow weeds before they drop their seeds. If they’re covered in flowers, seed pods, and so on, it might be too late to mow them. Failure to follow this suggestion can spread weeds everywhere. Some weeds can pick up with the wind and blow throughout the yard right when they’re mowed.

Never Mow Weeds That Are too Tall

Much like the previous suggestion, tall weeds often lead to more issues when they’re mowed. Not only are they harder to handle for a basic push mower, but they’re also prone to spreading seeds everywhere. Pushing your lawnmower to its limits and cutting tall weeds can harm the wheels and cause them to mow uneven lines through the grass.

Remove the Mulch as Soon as Possible

Most mulch is very effective for growing plants. In fact, I have an article about growing plants through mulch. However, mulch from mowing weeds is typically packed with seeds and debris that can grow more weeds. When a weed sets its roots, it absorbs nutrients intended for other plants in the yard, depriving them of what they need to grow.

If it’s too late to mow the weeds because they’re shedding seeds, are too tall, or inconvenient to mow, proceed to the next section.

Should I Remove Weeds Before Mowing?

Although it’s a bit tedious and time-consuming, your best option is always to remove the weeds before mowing your yard. This can be quite frustrating if you have a big lawn for obvious reasons. Bio-Advanced recommends raking the weeds to make them face upright before mowing the area.

Here’s how you can remove weeds before mowing:

  1. Rake the weeds as mentioned above. This will pull seeds upward and allow you to grab them from the base for the best chance of removing the roots.
  2. Firmly grasp the weed by its base and pull it until the roots come out. Many weeds are capable of growing back if they have their roots in the ground.
  3. Use a lawn-friendly weed herbicide. The Ortho WeedClear Weed Killer is a top-notch choice for those who want to get rid of dandelions, clover, crabgrass, and many other weeds without ruining their lawn.
  4. Mow the lawn to remove excess weed clippings or grass caught in the area. Dispose of the mulch and don’t use it as fertilizer for other plants since it might have seeds in it.

The good news is once you do this process, you only need to do it about one time per season. Weeds can’t overwhelm the lawn if you’re always taking care of it, which is partially what we’ll dive into in the next subheading.

Does Regular Mowing Kill Weeds?

Regular mowing kills weeds because it shades the soil with dense grass. SF Gate shows most lawns grow thicker blades, providing cover to the dirt below. Weeds need an open environment with lots of sunlight, so a dense lawn isn’t an inviting environment.

So, how often should you mow your lawn to prevent weeds from growing?

You should mow your lawn once per week, or however often you need to do it to keep the blades at least two inches tall. Life Hacker provides a helpful tip of never mowing the grass down to less than one-third of its size.

For example, if the grass is nine inches tall, don’t cut it below three inches in the first week. Breaking this suggestion can cause the grass blades to get too thin. Wait for another week, then cut it down to the previously recommended two-inch length.

While regular mowing might not get rid of weeds that are dropping seeds, it might be the best prevention method available once you try the previous four-step method. If you don’t want to deal with the constant maintenance, consider Xeriscaping. I talk a lot about this subject in my article analyzing why many lawns aren’t environmentally friendly.

But what can you do if your lawn is already packed full of weeds? Read on

How to Mow a Lawn Full of Weeds

Mowing a lawn full of weeds is a long process that’s well-worth the time it takes to make your yard look better. Some weeds are low-sitting and challenging to remove by the root, while others are thick and tall and horrible for lawnmowers.

In some cases, it’d be best to use a weed whacker to cut down tall, dense weeds. You wouldn’t want to ruin your mower’s blades. Consider using a weed whacker with metal blades rather than strings, if possible. They’re great for chopping through the roots of weeds.

Wear a tough pair of textured gloves and rip out as many weeds as you can. If there’s not much grass, you can till the soil, add fertilizer, and plant new grass once all of the weeds are removed. Some people prefer using a weed and grass killer to start fresh. If you do this, wait a few weeks to plant new grass for the chemicals to dissolve and dissipate.

Note: I’ve ruined a high-quality lawnmower trying to cut through tall, thick weeds. Contrary to what the companies want you to belief, lawnmowers are made for grass, not branch-thick weeds and roots. Don’t risk your lawn equipment trying to save time! You’ll end up having to get more machinery and tools.

Conclusion

After mowing through a backyard full of dense, thick, painful weeds, I can tell you the best solution is to cut them down and remove their stems. Use an all-natural herbicide to prevent the weeds from coming back, then keep your lawn mowed to make it look nice and neat.

Weeds are a headache that almost every homeowner has to deal with. By following these suggestions, you can stop the weeds by getting rid of them before and after mowing the lawn.

Jonah

Jonah loves researching new ways to grow and maintain healthy plants. If he's not writing on one of his many blogs, he's likely playing acoustic guitar, watching survival shows, or mapping routes for future road trips.

Recent Posts