What Is Organic Material? (Plus 5 Reasons It Is Important)

If you’ve done any research on gardening at all, you’ve most likely seen some mention of how important it is to use organic materials for your plants. But what exactly does that mean, and how can you implement it in your garden? 

Simply put, organic material is a component derived from living matter, such as wood, grass clippings, or compost. When used correctly, organic materials can provide a wealth of valuable nutrients to your plants, among many other benefits.

Like with most plant care decisions, however, there is a catch: you can’t just toss in any organic material into your garden without doing your research. This article will explore what makes something organic, and how it can benefit your garden. 

What is Organic Material?

In the gardening world, the phrase “organic material” refers to a component or amendment you add to the soil that is made up of living things. Some examples of organic materials include compost, certain types of mulch, lawn clippings, manure, and beneficial fungi. 

fungus on ground
You might see mushrooms taking up residence on organic material (like fallen trees) to break it down into something that looks more like soil.

Organic Material Vs. Organic Matter

There is some debate amongst horticultural experts on the difference between organic material and organic matter. Some, including the Noble Research Institute, use the phrase “organic matter” to refer to the decomposed components that come from organic materials. In other words, organic material slowly breaks down to become organic matter. 

Organic material comes from living matter (like wood, grass clippings, etc.)

Other research-based institutions use the two terms interchangeably. Since many hobbyists and experts use both terms to describe components that are added to soil, this article will do the same. 

What Is Organic Material Used For?

Organic materials are used to optimize the health and fertility of soil in both commercial and residential settings. Adding organic amendments is beneficial for flowers, foliar plants, and edible plants. 

cutting grass
Grass clippings are a source of organic material, which contains plenty of nitrogen.

You can use different organic materials to accomplish various goals depending on the type of soil you’re working with, as well as the needs of your plants. In general, organic materials are used for:

  • Improving soil health
  • Aerating the soil 
  • Preventing compaction
  • Providing nutrients for plants and beneficial organisms in the soil
  • Improving drainage

Why Are Organic Materials Important?

If you’re a newer gardener, you’ve likely read about the importance of having good quality, well-draining, nutrient-rich soil. But what makes your soil “good quality”, and why? 

According to the United States Department of Agriculture, soil health refers to the “continued capacity of soil to function as a vital living ecosystem that sustains plants, animals, and humans”. When soil is healthy, it benefits anything that grows, as well as our air and water.

Having enough organic material in your soil is vital to the health of earthworms, bacteria, and other beneficial creatures.

There are many elements that affect the quality of your soil, including:


Soil texture refers to the proportions of silt, sand, and clay that are present. Each of those minerals have different qualities. Sand consists of larger particles that allow for drainage and aeration. Clay and silt hold onto nutrients and retain water.

clay soil
If you have heavy clay soil, adding some organic material (perhaps in the form of compost) can help to improve drainage.

Each soil component has its purpose, so a good balance of the three is ideal. The optimal ratio depends on the specific needs of your garden.  

Soil Ecosystem

Regardless of what you can see in the dirt, it’s difficult to fathom the sheer abundance of living organisms that are present there. 15% of soil is made up of living organisms – many of which are microscopic.

fungus on wood mulch
Fungi help to break down grass, leaves, wood, and other formerly living things into organic material.

Earthworms, fungi, beneficial bacteria, and insects all perform specific functions that are essential to soil health. Earthworms, for example, create underground tunnels that help to aerate the soil, and their waste (castings) provide nutrients for plants.

Organic Matter

In addition to living organisms in the soil, there are many other organic materials that are naturally present in soil, such as dead and decomposing organisms, and the substances produced as a result of decomposition. 


Aeration is simply the process of adding air to a material. When growing plants (both indoors and outdoors), having enough space for air to pass through the soil can greatly impact the overal health and lifespan of your plants. 

root rot
Root rot causes roots to turn brown and mushy.

When you add organic materials to your garden, you’re increasing the pore space around the roots of your plants, which allows them to breathe, absorb water, and intake vital nutrients.

Moisture Retention 

The composition of your soil defines the amount of water that is available to your plants. The same pore spaces that allow for aeration also allow water to flow through and reach the roots of your plants. 

The size of the space between each soil particle determines how much moisture the medium can retain. For instance, in sandy soil, the particles are large, so water and air flow through quickly.

This means that the soil dries out relatively quickly. This is ideal for desert plants like cacti, but not for tropical plants that prefer the soil to stay moderately moist.

Peanut Cactus
Cacti do not need much moisture, but other plants do, and adding organic material can help to retain water in dry, sandy soil.

What Are Examples Of Organic Materials?

When it comes to gardening, whether your soil is of good quality depends on what you’re trying to grow. Many plants have different needs, so there are no definitive, universal soil characteristics that work for everyone.

Here are some examples of organic materials, and their uses: 


Compost is comprised of decomposed organic material such as kitchen scraps, twigs, and leaves. As it breaks down, it becomes chock full of valuable nutrients for your plants and soil.

Compost is a great source of organic material for a garden.

According to many experts, such as Washington State University’s Extension Office, compost helps to build healthy root systems, protects your garden from disease and pests, decreases soil erosion, and aerates the soil. 

You can use compost in the garden by working it into the top few inches of your soil when you’re planting, using it as mulch, or including it in your potting mix for container gardening.

(You can learn all about how to make your own compost here).

Worm Castings (A.K.A. Worm Poop)

Worm castings are a popular source of fertilizer that plant owners use in their outdoor gardens, lawns, and even potting mix for houseplants. When waste traverses through a worm’s digestive tract, it forms a coating on the casting that enables the nutrients inside to be released gradually into the soil. 

Worm castings are another good source of organic material for a garden.

Since the nutrients are dispersed over time, worm castings provide a steady source of nutrients over time, and will not burn the roots of even the most sensitive plants.   

(You can learn how to attract more worms to your garden here).

Peat Moss

Peat moss is an extremely popular ingredient in many potting soils. It can hold several times its weight in water, making it ideal for seed starting, and as a moisture-retaining component in potting mix. 

(You can learn how to make homemade potting soil here).

While its benefits are clear, there some environmental concerns about the harvesting process. Peat comes from peat bogs, which store a significant amount of soil carbon. Harvesting the peat releases carbon dioxide and creates a risk of peatland fires. 

sphagnum peat moss
Peat moss is a common ingredient in potting soil. It adds organic material and helps to retain moisture.
Image courtesy of:
Ragesoss via:
Wikimedia Commons: https://commons.

To collect peat, the living surface of the bog is removed to get to the layers underneath. Peat mining requires removal of materials that take centuries to form, as it only grows about 1/16 of an inch each year.  

For a more sustainable and fairly comparable alternative, coco coir is a great choice. It is made out of the fibers of coconut shells, and possesses many of the same qualities as peat. 


Many gardeners use mulch as a soil cover to retain moisture and inhibit weed growth. Shredded hardwood is one of the most popular examples of organic mulch.

red cedar mulch
Wood chips from cedar and other trees are often used as mulch. Eventually, they will decay, adding nutrients and organic material to the soil.

Other examples include leaves, plant residue, straw, and pine needles. Some of the many benefits of using organic mulch in your garden include:

  • Regulating soil temperature
  • Retaining moisture 
  • Attracting beneficial soil organisms
  • Minimizing weed growth

(You can learn what to do with old mulch here).

What Is Inorganic Material?

An inorganic material is anything that is not derived from a living thing. Clay, silt, and sand are some examples of naturally occurring inorganic materials that are found in soil. There are also many types of inorganic materials that gardeners purchase and use, including:


While there are many beneficial organic fertilizers that plants appreciate, inorganic fertilizers are a great way to deliver a dose of readily available nutrients directly to your plants.

ammonium nitrate
Inorganic fertilizer may have its place in growing plants where there is a lack of a particular nutrient in the soil.

Some plants, like tomatoes and peppers, require larger amounts of nitrogen. Therefore, growers often use fertilizer specifically formulated for nitrogen-loving plants.


Inorganic mulch includes synthetic materials like rubber, stone, and plastic, which are used to cover the soil. Since those materials don’t decompose, it saves the cost of having to replace the mulch every year or so.

Gravel is one inorganic alternative to wood mulch. It won’t decay, but it won’t add nutrients or organic material to soil either.

Inorganic mulch, however, does not offer any nutritional benefits to the soil, and may have other potentially harmful effects. 

(You can learn about some alternatives to wood mulch here).

Landscape Fabric

Landscape fabric is one example of an inorganic addition that might do more harm than good. While it temporarily acts as a barrier to weed growth, that effect generally doesn’t last long.

landscape fabric black mulch
Landscape fabric is an inorganic material, so it won’t add nutrients or organic material to soil.

Plus, replacing it can be time-consuming and laborious. The fabric can prevent water and other nutrients from reaching the plants roots, and can also inhibit root growth. 


There is no one-size-fits-all answer to the question of what type of materials to use in your garden. The best way to find out what works for you is to research your plants,familiarize yourself with the characteristics of your soil, and experiment. 

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About the author:
Kathryn is a plant enthusiast and freelance content writer who specializes in home and garden topics. Based in New York, you can get in touch with Kathryn at https://kathrynflegal.journoportfolio.com/.

Kathryn F.

Jon M

Hi, I'm Jon. Let's solve your gardening problems, spend more time growing, and get the best harvest every year!

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