How Does Organic Mulch Work?

Allie Ogletree
Written by Allie Ogletree
Updated February 14, 2022
A garden with ornamental plants
Photo: LuckyRiga / Adobe Stock


  • Mulching helps retain moisture and protect your plants from the sun, wind, rain, and cold.

  • Unlike inorganic mulch, organic mulch decomposes and nourishes the soil.

  • Organic mulch costs anywhere from $30 to $110 per cubic yard.

  • Wood, straw, and pine needles are a few popular types of organic mulch.

  • It costs around $500 for the mulch, delivery, and installation for a standard 500-square foot garden.

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Before you bag up those grass clippings and leaves, you might want to reconsider and use them to keep your yard looking pristine instead. Organic mulch provides an environmentally-friendly alternative to artificial or treated mulches. Here’s how organic mulch works and what types of organic mulches you can use in your landscape.

What Is Mulching?

Mulching is the practice of covering the soil around the vegetables, plants, and trees in your yard with a layer of material. This boosts the various natural processes that help grow the plants you want and suppress those pesky weeds you’d rather not see in your garden beds.

How Does Mulch Work?

Though there are many types of mulch, all mulch works similarly to retain moisture, keep out weeds, and prevent extreme weather from harming your yard. How you spread mulch can be almost as important as what kind of mulch you use, so here is the know-how on how mulch works to protect and nourish plants:

Tree Mulch

Those mulch rings that you see while driving past a well-designed landscape on your daily commute to work are more than just piles of wood shreddings. They’re also an effective method for providing moisture retention and soil cooling also to keep those newly-planted trees protected from harsh, dry weather.

Mulching keeps grass and other weeds away from saplings that need water and nutrients to develop into strong trees by blocking sunlight to the ground beneath the material. This suppresses weeds and protects the already-established plants in your yard or garden.

Garden Mulch

In your garden bed, mulch works just like it does for trees. Since mulch acts as a protective layer over the top of your soil, it retains moisture, insulates against evaporation from the hot summer sun, and protects against wind erosion that can leave your yard looking depleted of soil over time.

All of these perks encourage the plants in your yard to grow while preventing weeds from competing with your garden.

Pathway Mulch

You can also use a thick layer of mulch to turn that muddy walkway into a natural, more informal path. It also blocks unsightly weeds from popping up in your pathways.

Inorganic Mulch vs. Organic Mulch

Inorganic mulch can either be artificial or a mined mineral. Examples include stone, gravel, rubber chips, plastic sheeting, landscape fabric, and other materials that don’t break down. Since these materials don’t break down, your landscape won’t need to be replenished much over time. At the same time, inorganic mulch increases the temperatures of the soil and plants and doesn’t boost your soil’s nutrients.

Organic mulch, on the other hand, is different from inorganic mulch made from organic matter that breaks down over time and adds nutrients to the soil that feeds plants and keeps them healthy and vibrant in your yard.

What Are the Benefits of Organic Mulch?

A man wearing gardening gloves spreading brown bark mulch
Photo: Jon / Adobe Stock

There are numerous benefits to using organic mulch for your yard. A few pros to choosing mulch are as follows:

  • Mulch is nutritional: Unlike inorganic mulch, which doesn’t break down much over time, organic mulch decomposes quickly and adds nutrients from microorganisms to the soil in the process.

  • Mulch preserves water: Mulch helps preserve water lost through evaporation by retaining water underneath it.

  • Mulch is insulating: Mulch can protect plants from freezing temperatures and scorching summer heat.

  • Mulch prevents weed growth: Mulch keeps seeds from getting to your soil and blocks sunlight, which in turn keeps out unwanted plants.

  • Mulch protects against soil erosion: For areas that are susceptible to heavy rain, wind, and snow, mulch can prevent soil loss through erosion.

What Are the Disadvantages of Organic Mulch?

Organic mulch, as with regular mulch, comes with a few disadvantages. These include:

  • Organic mulch is more costly than inorganic mulch: While inorganic mulch is more expensive upfront, with rubber mulch costing between $80 to $160 per cubic yard, organic mulch, which costs between $30 and $110 per cubic yard on average, needs to be replaced as it decomposes.

  • Mulch can harbor unwanted critters: Termites, roaches, ants, mice, and snakes are just a few pests you might find in mulch.

  • You have to add more mulch over time: Though mulch is beneficial in that it breaks down and adds nutrients to the soil, this can be a con for homeowners who don’t want to have to repeat the installation process and spend extra money to add more mulch.

  • Organic mulch can harm plants if misapplied: You should apply mulch loosely to prevent it from becoming anaerobic as it decomposes, which can make the soil too acidic and actually kill your plants.

Types of Organic Mulch

A variety of sources can create organic mulch. Wood chips, bark, sawdust, shredded leaves, pine needles, hay, and straw all make effective organic mulches. The one thing they have in common is that they ultimately decay into humus in the soil, which improves the growing environment for plants by adding nutrients to the soil.

Different mulch materials have different properties, so let’s look at how each type of organic mulch works to see which mulch might be right for your home.

Wood Mulch

Just looking at wood mulch alone gives you a broad selection of organic options for your landscaping needs. Most wood chips and hardwood mulches cost between $30 to $110, depending on which one you choose.

Popular types of wood mulches include:

  • Natural colored wood-based mulch

  • Colored mulch, usually dyed red or black

  • Bark mulch

  • Cedar mulch

  • Pine peelings

If you’re in an area prone to termites, cedar mulch is a great option because it contains natural pest-repelling oils. It does fall on the higher end of the price point, at around $100 per cubic yard, but keeping your property free from termite damage will save you more money down the line.

Straw and Hay Mulch

Straw and hay are very inexpensive, easy to place, and effective at adding nutrients to your yard. Straw mulch costs around $40 per cubic yard, whereas hay can be free if you have tall grass on your property.

Keep in mind, these options have a few negatives, as well. They both have a very distinct aesthetic look that might not match what you’re trying to achieve with your yard. Straw is also fluffy and can blow away in the wind, while hay attracts snails and slugs that eat crops.

Cocoa Mulch

Even chocolate can help your yard, in a way. Cocoa mulch, made from cocoa bean hulls, is an effective mulch for flower beds, adds a pleasant aroma, and costs about $35 per cubic yard. This mulch is also a natural pest repellent. However, cocoa mulch is not safe for dogs, so avoid spreading it if you have a dog in the family.

Pine Needle Mulch

Pine needles tend to stick together and last a long time, so they’re good for areas where you don’t want to have to replenish more than once a year. Pine needle mulch is warm and attractive in garden beds, but it’s also one of the most expensive, coming in at $150 per cubic yard on average.

On top of that, the needles are acidic and will make the soil too acidic for most plants to grow if your home has plants that aren’t ideal for acidic soil. If you already have pine trees in your yard, however, your soil is likely already more acidic and won’t affect existing plants. You might be able to grow some plants underneath your pine trees thanks to pine needles acting as mulch.


Though technically not mulch, compost works just as effectively as any organic mulch, as it is rich in nutrients. You can buy it by the bag for around $60 per cubic yard or make your own compost pile with yard clippings and food waste.

Which Organic Mulch Works Best for Your Yard?

All organic mulch works to effectively improve your yard’s soil quality while keeping weeds and water evaporation to a minimum. At the same time, not all yards need water retention. In fact, water retention in a climate that is already very humid and moist can increase mold and decay in the garden.

As always, speak with a mulch and topsoil professional near you to determine which type of mulch will work best with your yard to get the most out of your landscape. Mulch costs around $500 for the installation, delivery, and material for a typical 500-square foot garden.

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