Mulching vs. Bagging Grass Clippings: Which Is Better for Your Lawn?

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Many homeowners face the conundrum of whether to mulch or bag grass clippings after they’ve mowed the lawn. Mulching, which involves using a mulch kit and mulch blade to shred grass clippings into tiny pieces, is typically the best option. Mulched clippings are free fertilizer that return nutrients to your lawn. By recycling those clippings, you’re also helping the environment by reducing the amount of yard waste that ends up in the local landfill. 

While mulching may be the preferred way to cut your lawn, there are times when putting the bagging attachment on your mower makes the most sense. Bagging is the best option when the grass is too tall for mulching or when you plan to use the clippings for compost. We sought help from Teresa Watkins, a landscaping designer and consultant for Sustainable Horticultural Environments for guidance on when to mulch and when to bag.  

Mulching Grass

Mulching grass when you mow a lawn involves using a mulch kit, which is a lawnmower attachment that prevents the grass clippings from exiting out the side discharge of your mowing deck. By trapping the clippings inside the deck, the mower blade cuts each blade of grass multiple times instead of just once, hence producing finer clippings that break down more quickly in your lawn. 

Advantages of Mulching Grass

• Free fertilizer: Mulched grass clippings are good for your lawn. They are high in nitrogen, and as they break down on your lawn, they nourish the soil and feed the grass, reducing the amount of fertilizer you need to add. “Grass blades that are left on the lawn will decompose, providing nutrients to the soil which will benefit the turf in the future,” Watkins says. 
• Moisture retention: Lawn clippings also help to shield the soil from the sun, which helps your lawn to retain moisture so you don’t have to water it as much. 
• Better for the environment: Since those clippings stay in your lawn, they don’t end up in the local landfill where they can pile up and create methane, a greenhouse gas that causes global warming. 

Disadvantages of Mulching Grass

• It’s messier. Mulching leaves lawn clippings on the grass, giving it a messier appearance when you’re done. Plus, if your lawn sees a lot of foot traffic, those clippings will end up on shoes and clothes. 
• Makes weeds worse. If you have a lot of weeds in your lawn, mulching will spread weed seed, making the problem even worse. 
• Spread disease: If your lawn is suffering from disease or pests, mulching the clippings will only spread those problems around your lawn. 

Bagging Grass

Most walk-behind mowers include bagging kits. As you mow, the blade sends the clippings from the deck into the collection bag. Once the bag is full, you remove it and dump the clippings into a collection bag or bin for disposal. 

Advantages of Bagging Grass Clippings

• Cleaner look. As you ponder whether you should bag your grass clippings, consider that if you bag them, when you finish your lawn there aren’t grass clippings lying all over the yard, giving it a cleaner look. 
• Ideal for higher-traffic lawns. If your lawn sees frequent foot traffic from pets and people, bagging is a good option as those grass clippings won’t end up on shoes and paws. 
• Good for composting. Grass clippings make great “green” material for your compost bin. Bagging your clippings makes it easy to transport those clippings to your compost bin. 

Disadvantages of Bagging Grass

• Bad for the environment. Collecting clippings for waste pickup means they end up in your local landfill. When grass clippings pile up, they produce methane, a greenhouse gas that contributes to global warming. 
• It takes longer. Bagging the grass means you’ll need to stop periodically to empty the bag, which makes the task of mowing your lawn more time consuming and labor intensive. 
• Higher fertilization costs. Leaving grass clippings on your lawns adds vital nitrogen and phosphorus to the soil. By removing the clippings, you’ll need to make up for it by applying more fertilizer.

Tips for Mulching Grass Clippings

• Use the right equipment. Mulching your lawn properly requires a special mulching blade and a mulch kit that blocks the side discharge of your mower. Simply mowing your yard with the side discharge won’t do the trick as it won’t shred the clippings into small pieces that will break down quickly in your yard. If the clippings are too large, they’ll clump on top of the grass, choking your lawn. Note: Most modern mowers are equipped with 3-in-1 blades that are capable of mulching, bagging, and side discharge, eliminating the need to install a different blade for each type of cutting.
• Mow often. Mulching works best when you’re following the one-third rule and only removing about an inch of grass at a time, Watkins says. “If you mow less frequently and cut off longer blades, they take longer to decompose and may cause issues,”  she says. 

Photo: Lowe’s

Tips for Bagging Grass Clippings

• Mow dry. Wet grass can clump and clog up the bagging chute. Wait until the grass is completely dry before bagging it. 
• Empty often. Don’t wait for your bag to be completely full before you empty it. Your mower has a harder time depositing clippings in the bag as it nears capacity, causing it to leave some clippings on the lawn. It’s also much harder to empty a packed bag. 
• Use a two-step process for tall grass. If your lawn is well past due for a cut, attempting to bag it will only clog your bagger. There’s a better strategy:
  • Mow the lawn by side discharging it (you may need to add a side discharge attachment), which will leave long clippings sitting on the lawn. 
  • Add your bagging attachment and go back over the lawn. Your mower will collect the clippings off the yard without clogging. 

When to Bag and When To Mulch

While mulching generally leads to a healthy lawn, there are times when it makes sense to put on the bagging attachment. Here are some situations in which bagging might be the better option, and a few eco-friendly arguments for leaving the clippings in place.

Bag when:

• The grass is too long. If the grass has grown so long that you have to remove more than 1/3 of its length, then bag it. Attempting to mulch cut an overgrown lawn will leave large clumps of clippings on your lawn that will choke the grass. 
• You have a lot of weeds or diseases. If your lawn has excessive weeds or you’re treating it for diseases or pests, then bag it. “Bagging the clippings is important especially when you have weeds that have gone to seed or insect issues,” Watkins says. 
• You have thatch issues. If you’re dealing with excessive thatch in your yard, mulching can make it worse. “Adding more organic material (extra grass blades) will only increase the thatch,” Watkins says. Bag until you’ve resolved your thatch issue. 
• You’re entertaining in the yard. If you’re mowing your lawn just prior to a barbecue or other backyard social gathering, bag it so your guests don’t have to walk through grass clippings.
• You’re planning to compost. Bag if you’re planning to add those grass clippings to your compost bin or if you’re going to use them to mulch your garden. 

Mulch when:

• You can follow the 1/3 rule. Mulch when you can follow the 1/3 rule and aren’t going to remove more than an inch or so of length from the grass. 
• You want a healthy lawn: Since mulching returns nutrients into the soil through the nitrogen-rich clippings, it’s much healthier for your lawn than bagging.
• You want to go green: Mulching isn’t just good for your lawn, it’s also good for the environment by keeping grass clippings out of your local landfill.  

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