Disadvantages of mulching grass are various, and some might even surprise you, hence mulching clippings of grass have been known to require more maintenance from the mower. Spreading organic mulches over the lawn only sometimes leads to a healthy and thriving lawn.

11 Disadvantages of Mulching Grass

This process has been known to occasionally cause undue soil dampness, a messy lawn, and pest infestations. It could also create a mess in the lawn and attract pests to the grass.

Read our complete list of all the major disadvantages you didn’t know came with regular mulching of lawn.

List of Disadvantages of Mulching Grass 

1. Soil Stays Damp Longer

Soil Stays Damp Longer

  • Thick layer of mulch
  • Prevention of water from evaporation
  • Fungal overgrowth
  • Root rot
Influencing Factor
  • Hot weather
  • Humid weather
  • Use a thin layer of mulch
  • Spread mulch evenly

When a very thick layer of grass mulch is spread over the soil, this can cause the soil to become and then stay damp for a long time. This rise in humidity, of course, is not much of a good situation and the reason is that damp soil leads to the rotting of grassroots and promotes fungal overgrowth. A constantly damp soil also attracts harmful sap-sucking pests to the lawn. 

On the other hand, this problem with mulch becomes more pertinent during the hot and humid summertime, which is also when the grass would begin to grow and establish at its peak.

Not only does the soil stay damp, but it also becomes more compact, which means that the drainage is affected badly. Moreover, when the soil is compact, it means that it doesn’t have the right aeration subjected to it. 

2. Creating A Messy Situation

Creating A Messy Situation

  • Grass clippings
  • Windy day
  • Having to clean the lawn
  • Clippings clump together
Influencing Factors
  • Wet grass
  • Non-mulching mowers
How To Fix This
  • Use a mulching mower
  • Bag clippings instead

Even though a mulching mower cuts grass clippings into fine little pieces, the result is an extremely messy lawn. No matter how much the mulching mower manufacturer that you have has claims to give you pitch-perfect covering, the reality will be much worse. The mulched clippings will inevitably clump together all over the lawn to create weirdly-shaped mounds. 

The clippings will also get stuck to the lawn mower’s deck, which, in turn, will need more frequent cleaning, and this would be a worrying and an exhausting cause for you. Walking on the lawn will become a big hassle, too, because this protection layer is one that will get stuck all over your boots and shoes, resulting into a cleaning process after the work is done. 

On the other hand, remember that these clippings will get strewn all over the lawn, the patio, and even on the fence and walls on a windy day. In this case, you are opening the door to content lawn care and cleaning when you choose mulch over bagging grass clippings.

3. The Lawn Mower Maintenance Goes Up

The Lawn Mower Maintenance Goes Up

  • Mower blades dull faster
  • More fuel is used up
  • More mower maintenance
  • More spending on fuel
Influencing Factors

Lawn mower blades dull much more quickly when used to make mulch cut grass blades regularly. This goes for mulching and non-mulching blades because mulching takes more effort than simply mowing grass.

However, under usual circumstances, your blades must be sharpened only once per year, preferably before winterizing them in a perfect manner so that they would stay neat. On the other hand, in the case of regular mulching, the blade will have to be mulched about three to four times more than that.

One thing you can do to stop the wearing down of blades is to perform this process only when the grass has been cut low or when only a small portion of the lawn is mowed. When you do so it would also increase the maintenance need of your mower that would otherwise not be a necessary requirement. 

You will have to clean the air filters more often, and the spark plug will need frequent changes. Mulching sounds much less useful when you think about all the work that will eventually go into it.

4. The Soil Might Overheat

The Soil Might Overheat


  • Mulch thicker than two to four inches
  • Poor aeration 
  • An overheated soil causes the roots to heat
  • Promotes fungal growth
Influencing Factors
  • Hot weather
  • Humid and rainy days
  • Use a thin layer of mulch
  • Carry out regular soil aeration

Mulch must be two to four inches thick over your grass. When using an excessively thick layer of this part of the grass, there is a risk of overheating the soil during the long, hot summer days. The moisture locked in the protection and the lack of proper ventilation are responsible for causing this. 

When the soil overheats, then it would cause different problems, and it may even become weaker in its growth. What you should do is aerate it, so that you would be avoiding this manner, because you wouldn’t want it to become weaker gradually.

5. Production of Hydrogen Sulfide

Production of Hydrogen Sulfide

  • A very thick layer of mulch
  • Decaying grass mulch 
  • Hydrogen sulfide is toxic for the grass
  • It is toxic for animals
Influencing Factors
  • Dehydrated grass that gets burned easily
  • Keep pets out

One rare but potentially more risky consequence of mulching grass clippings over the lawn is the production of hydrogen sulfide gas. This usually happens when a thick layer, in this case, will spread compactly over the lawn. The thing with hydrogen sulfide is that it is a gas that is toxic for both pets and humans. 

In this case, you must not panic just yet because mulch’s amount of hydrogen peroxide is not enough to produce serious toxicity to you and your pets. However, the risk persists, especially if you have nosy pets sniffing the lawn, as they will create somewhat of a hazard. The real risk posed by hydrogen peroxide is to the grass growing in the lawn because it gets burnt.

6. Fertilization Is a Risk

Fertilization Is a Risk

  • Mulch decomposes and provides nutrients to the grass
  • Combining mulch with fertilizer leads to over fertilizing
  • Grass roots get burned
  • Yellowing grass
Influencing Factors
  • Not diluting chemical fertilizers well
  • Fertilizing more than once per month
  • Fertilize only once every four weeks
  • Dilute the fertilizer to one-third of its concentration

A couple of problems come with combining chemical fertilizer and mulch simultaneously. First, mulch itself breaks down rapidly to convert into organic fertilizer for the grass.

However, if you pour a commercial fertilizer on top of it, this could lead to over-fertilizing, which is just as bad as under-fertilizing for the grass, which is why you should be mindful about it and abstain from doing so. 

In addition, the second thing you need to worry about is liquid fertilizer burning the grass blades off and turning them yellow, as they would begin to lose their color, and this happens from the layer of extra grass over live grass, the fertilizer will stay there longer.

Even if you use a well-diluted fertilizer, it would still end up burning grass and causing more harm than good.

7. The Mower Needs More Work

The Mower Needs More Work

  • Mulching blades need more engine power
  • Consume more fuel
  • The engine wears out much faster
  • Higher cost of fuel
Influencing Factor
  • Using regular blades
  • Bag clippings and mulch them by hand
  • Buy ready made mulch

If you want to use this cover that traps moisture in order to improve the quality of your lawn, then the mowed grass needs to be chopped down very finely. With a non-mulching type of mower, you will need to collect the cut grass pieces and then cut them down yourself till they are the right size. This is too much yard work and effort after growing through grass mowing. 

The reason behind this is that your ordinary mower will have to put in a lot of effort and power, and it still will need to do a better job. To save yourself from all that trouble, you need to save some money and buy a good mulching lawn mower.

This would be the factor that would make sure how the mulch is of the highest quality and in the shortest possible time.

8. Pests Are Attracted To Mulch

Pests Are Attracted To Mulch

  • Mulch creates a damp environment that attracts pests
  • Pests are attracted to the nutrients
  • Pest infestation
  • The grass turns thin and yellow
Influencing Factors
  • Lawns that have not been treated for pest before
  • Humid soil conditions
  • Remove mulch
  • Use insecticides

This is among the worst consequences of covering the lawn with mulch grass after mowing. All sorts of pests are attracted to this mulch, which also serves as their hiding ground. 

To narrow it down, this is the case of some sap-sucking pests like spider mites here and larger ones like slugs and snails, which would damage the lawn in the long run. The thing with snails and slugs is that they like to munch on the clippings and live grass blades. These pets will end up destroying an otherwise healthy lawn because they are attracted to the layer of mulch covering it. 

9. Might Spread Weeds

Might Spread Weeds

  • Mulch might contain weed seeds
  • Homemade mulch
  • Weed growth
  • Grass thinning
Influencing Factors
  • Making mulch from a weed infested lawn
  • Weed removal
  • Buying store-bought mulch

Usually, when the grass is used to make mulch, what happens is that this grass is first mow from the lawn and then cut into small mulch-sized pieces. While the type that is produce by the mower will convert cut grass to mulch simultaneously, a regular mower or a weed trimmer will first cut grass, and then you must chop it up manually. 

During this process, you will find naturally ripe weed from the ground, which will get mixed up with the pieces that were cut. When this cover is laid down on the lawn, you will have to deal with an explosive growth of weeds and invasive species that you have contributed to spreading. 

This is such a common and inevitable consequence of mulching that it has caused many people to denounce mulching for the rest of their lives. You can remove weeds from the entire lawn and mow it for mulching. Yes, this is just as tedious in practice as it sounds on hearing.

10. Cause Soil Dryness

Cause Soil Dryness

  • When more than four inches thick layer is used
  • Water doesn’t reach past mulch
  • Rainwater doesn’t reach the soil
Influencing Factors
  • Shallow roots
  • No underground source of water
  • Use a thin layer of mulch
  • Cut grass finely 

Using grass clippings as mulching has been known to lock moisture in the soil by preventing its evaporation into the air. However, sometimes when a very thick layer is used, it has the exact opposite effect. 

As you have placed this thick layer, now it is one responsible to only absorb any water you provide your lawn, and only a small amount will reach the soil. The lawn patches where the mulch layer is the thickest will start turning yellow and wispy from lack of moisture in the soil.

11. Clogs the Mower

Clogs the Mower

  • Cutting wet grass
  • Grass clippings form clumps
  • It clogs mower deck
  • Wet grass attracts disease and pests
Influencing Factors
  • Mowing after rain
  • Mowing after watering
  • Only turning dry grass into mulch

Another key disadvantage of mulching is that it can only be carried out when the grass and the soil are completely dry. Otherwise, you look at a huge mess and an unbearable amount of lawn care.

This will end up ripping the grass instead of mowing it neatly, and the mulch must also be cut properly. The mulch pieces will clump together on the lawn and within the mower deck.  The clumps of stuck-together wet mulch serve as a breeding ground for fungal infections and pest infestations.

The lawn will have a bad appearance overall and warrant a thorough cleanup. You must use a putty knife to scrape the mulch from the deck and clogged chutes. Only mow grass and mulch it if it is dry and there is no chance of impending rain for the next few days.


Before concluding our guide on the disadvantages of mulching too much, here is a much-needed recap:

  • Mulching too thick can cause the soil to stay damp for a long time, developing fungus and attracting pests.
  • The lawn looks messy and unkempt every time it is mulched, no matter how finely you chop it up.
  • When you convert grass to mulch, there is a risk of spreading weeds and their spores around.

In this informative article, you read all the major negative side effects of mulching in great detail. Mulching is important to get a lush lawn, but be careful not to overdo it.

5/5 - (6 votes)
Evergreen Seeds