Should You Bag Grass Clippings If You Have Weeds?

Many people choose to leave their grass clippings on the lawn after mowing.

Lawn clippings are rich in nitrogen and other essential nutrients which aid in grass growth and create a healthy green lawn.

However, if you have weeds in your yard, do you need to bag your clippings?

If you have weeds on your lawn, it is a good idea to bag your lawn clippings instead of leaving them on the lawn. The grass clippings may contain weed seeds, and if they remain on the lawn, the weeds will spread. Leaving the grass clippings with potential weed seeds on your yard may result in a weedy lawn.

Once you have a large number of weeds on your lawn, it is very time-consuming and expensive to eliminate them.

Read on for more information on what to do with your lawn clippings and how to eradicate weeds for a beautiful lawn.

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What Is Grass Clipping Bagging?

Bagging your lawn clippings involves either using a bagging mower or manually bagging the clippings after you are done mowing.

The bagged clippings are then put into a compost bin or a separate container for yard waste.

A push lawn sweeper will make it easier to collect the clippings if you do not have a bagging mower.

You may also use a rake, but this method is more difficult and time-consuming.

Many homeowners choose to bag their lawn clippings simply for better curb appeal or during the winter months.

Bagging is also recommended if you do not mow your yard regularly.

Longer grass clippings may clump up on your lawn and form a layer of thatch.

These clumps may also begin to rot and cause damage to the healthy lawn underneath.

What Is Mulching For Grass Clippings?

Mulching your lawn clippings simply means you allow them to fall back onto your lawn as you mow.

Eventually, these lawn clippings will decompose and release nitrogen, phosphorus, potassium, and other essential nutrients back onto your lawn.

Mulching your grass clippings will save you money on fertilizer as they provide up to 30% of the nutrients your grass needs for strong growth.

Using grass clippings as fertilizer also helps you avoid harmful chemicals in your yard.

The grass clippings will also help your lawn retain moisture.

There is also the added benefit of not picking up and bag the clippings when you are done mowing.

It is best to mulch your lawn clippings during the hottest months because the high temperatures and humidity help them decompose more quickly.

If your yard has patchy areas, mulching your grass clippings is a great way to naturally add essential nutrients to make your grass healthy again.

It is a good idea to rake the layer of grass clippings to spread them evenly over your lawn.

How Long Until Grass Clippings Decompose?

It usually takes around 3-4 weeks after mowing for grass clippings to decompose.

The clippings will reach the soil level within 1-2 weeks, and they will no longer be visible on your lawn.

When grass clippings are added to a compost, they will be completely broken down within 1-3 months.

Following the one-third rule when mowing is vital because the grass clippings will break down if shorter.

The one-third rule means you will not cut more than one-third of the length of your grass blade.

Even if you let your grass become overgrown, you will still only cut one-third of its length.

Cutting the grass too short all at once will cause it to become stressed, and the shorter grass also will not retain enough moisture or nutrients to stay healthy.

Never mow your yard when the grass is wet because the grass clippings will become clumped up.

These clumps of clippings will lead to thatch on your lawn and will prevent your grass from receiving the proper amount of sunlight, moisture, and nutrients.

For more details, check out our dedicated article on how long it takes grass clippings to decompose.

Does Mowing Spread Weeds?

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If you have weeds in your yard, mowing over them will cause them to spread.

The mower blades can spread weed seeds 5-10’ feet away from where the weeds are cut.

Weeds and seeds may also become stuck to your lawnmower blades and the mowing deck.

These seeds may then be transferred to other parts of your yard, where they will spread until you have a full-blown weed infestation.

To avoid spreading weeds when you mow, it is crucial to completely clean your lawnmower after mowing a lawn where weeds are present.

You may want to mow the areas of your yard without weeds first and then mow the areas containing weeds to avoid any cross-contamination.

Always clean your lawnmower when you are done, not only to prevent the spread of weeds but to keep your mower in excellent condition.

It is tough to simply avoid mowing your yard, especially during the spring when grass experiences rapid growth.

As previously stated, it is better to bag your grass clippings if you have weeds with seed heads to keep from spreading them to the rest of your yard.

Will Cutting Grass Short Kill Weeds?

Cutting your grass short is not an effective method for killing weeds or keeping your lawn healthy, and it is the most common lawn care mistake.

If you cut your grass too short with frequent lawn mowing, your yard will be more susceptible to weed issues, and it will also be difficult to maintain soil moisture.

The grass will be too short to prevent rapid water evaporation, and your turf will be more prone to damage from drought, heat, pests, and diseases.

Most grasses’ average recommended cutting height is between 2-3” inches.

The weeds will absorb the essential nutrients your grass needs until they have entirely overtaken your lawn.

Before they have flowered or formed seed heads, cutting the weeds will prevent them from spreading quickly, but it will not kill them.

It is not advisable to cut the weeds once they have flowered because they will spread the seeds quickly.

Even if you bag your grass clippings, there is still a chance you are spreading the weeds when you mow.

If you keep your grass reasonably short through regular mowing, you will likely be cutting the weeds before they flower or form seed heads, but there is no guarantee of this.

It is best to completely remove any weed growth before mowing your yard again.

Lawn Weeds Prone To Spreading Through Grass Clippings

Some lawn weeds are more prone to spreading than others, and they are usually more difficult to eliminate.

While clover does spread easily, it is one of the few types of weeds to benefit your yard.

Clover is not only pleasant to look at and has a nice smell, but it is excellent at preventing pests, and it helps to aerate your soil.

Clover also adds nitrogen to your soil, which keeps your turf healthy and easy to sustain.

On the other hand, crabgrass is a prolific type of weed, and it does not offer any benefits to your soil or lawn.

Crabgrass will spread quickly through seeds during the warmer season, but pieces of the weed stem will also take root in favorable conditions.

Mulching with clippings from crabgrass will significantly accelerate the spread of this weed, and it is very difficult to eradicate it.

Ragweed is another lawn weed that is easily spread because a single plant can produce up to 60,000 seeds per season.

If you mulch lawn clippings containing ragweed, you will quickly have an infestation of this week over your entire yard.

Purslane is also easily spread through stem fragments, which can take root wherever they land.

If you have crabgrass, ragweed, or purslane on your lawn, it is best to eliminate them before mowing or mulching with your grass clippings.

How To Deal With Thatch Caused From Leftover Grass Clippings

If you frequently mulch with your grass clippings, your yard may develop a layer of thatch.

This thatch buildup occurs when the clippings do not decompose before more are added to them.

A thick layer of thatch will prevent sunlight, oxygen, nutrients, and water from reaching the soil and your grass roots.

This thatch layer will cause your grass to become thin, and it may even begin to die off.

Following the one-third rule of mowing, thatch usually is not a problem because the grass clippings are short enough to decompose properly without building up in clumps.

If you have a lot of grass clippings on your lawn after mowing, you may need to rake them to spread them evenly across your lawn.

Using a mulching mower or adding a mulching attachment to your current lawn mower will cut the clippings into even smaller pieces, so thatching is less likely to happen.

A rake or a dethatching tool may be used to remove the thatch layer from your yard effectively.

To avoid thatch buildup in the future, never mow your yard when the grass is wet, and be sure not to cut too much of your grass at one time.

You may also consider bagging your grass clippings every time you mow and compost them.

Check out our article on the best way to pick up grass clippings.

How To Get Rid Of Weeds 

The first step in getting rid of weeds on your lawn is identifying the types of weeds you have.

Many selective herbicides on the market target only certain types of weeds while leaving your grass unharmed.

However, these methods of weed elimination are only effective if you are using the right products for the types of weeds on your lawn.

Stubborn weeds like crabgrass will easily spread through seeds, but it only grows in warm weather.

If you are mowing your lawn on a routine basis, the crabgrass will not grow large enough to form any seed heads.

If this is the case for you, it will still be safe to mulch your grass clippings on your lawn.

On the chance you do see crabgrass seed heads, your best option is to pull them out of your yard and dispose of them properly.

It is best for other weeds without discernable seed heads to just pull them out.

As long as you are able to pull out all of the weeds in your yard before you mow, it will be safe to mulch your grass clippings.

If there are too many weeds for you to be sure you pulled them all up, it is best to bag your grass clippings.

For extremely stubborn weed varieties, you may need to resort to using an herbicide to get them under control.

Using herbicides is tricky because if they are used incorrectly, you may cause severe damage to your lawn.

In addition to knowing which types of weeds are on your lawn, it is crucial to know your grass type.

Selective herbicides may be safe for one type of grass but not another, and you do not want to accidentally kill your otherwise healthy grass.

Always follow the application instructions on the herbicide label to avoid causing damage to your lawn.

Commonly Asked Questions

Does wood mulch help the grass grow?

Unlike using grass clippings as mulch on your lawn, wood mulch has the opposite effect and suppresses grass growth.

Sometimes wood mulch is used to suppress grass growth on purpose.

The nutrients in the mulch create a blank canvas for planting new grass seed once the old grass has completely died.

You may also use this method to kill grass in an area of your yard where you want to create a flower or vegetable garden.

How can I fix my lawn full of weeds without chemicals?

Regularly fertilizing your lawn will cause your grass to grow more dense and lush.

The natural thickness of your grass may be enough to crowd out any weeds.

Another method of getting rid of weeds without chemicals is to use an underground irrigation system to water your lawn.

Since the roots of weeds are usually shallow, the underground irrigation system will deprive the weeds of water as long as it is deep enough in the ground.

To prevent weeds around flower beds and trees, use a wood mulch or landscaping fabric.

Also, check out our post on the best weed killers for flower beds for more options.

What kills weeds permanently?

An herbicide containing glyphosate, such as Roundup, is very effective at permanently eliminating weeds.

Unfortunately, this powerful herbicide will also kill your grass and any other plant life touched by it.

The only sure-fire way to eliminate weeds is to pull them from the ground by hand.

While this method is very difficult and time-consuming, it is the safest way to remove weeds from your yard without causing issues.