Compost vs. Fertilizer (what they are and when to use them)

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Ah, yes, compost vs. fertilizer. It’s a common cause of confusion among new gardeners. To make the most of your gardening endeavors, you must understand what compost and fertilizer are, their unique differences, and when to use them.

Compost is a soil amendment comprising natural decayed matter and organic waste. A good quality compost makes the soil absorbent while enriching it with nutrients and healthy bacteria. Fertilizers are specifically formulated to provide nutrients directly to plants for improved health and growth.

food scraps decomposing into compost and person sprinkling fertilizer around plant

If you’re a vegetable gardener looking to increase the yield of your crops or a landscape gardener trying to improve the health of your flowers and plants, composts and fertilizers should be at the top of your list for optimal growing.

By the end of this article, you will know everything you need about compost vs. fertilizer, such as how they are made and when you should use them in your backyard garden. I’ll also answer some of the most common questions beginner and seasoned growers ask when creating your compost at home.

Humble Highlights

  • Save time by discovering the difference between compost and fertilizer, their benefits and drawbacks, and how each can boost growth for rewarding and full harvests! 
  •  Know when to use compost and fertilizer in your garden to determine if you can use them together or separately throughout the growing season. 
  •  Become eco-friendly by determining the environmental impact of compost and fertilizer with this made-for-you comparison chart so you can enhance your crops while preserving the surrounding landscape.

What Is The Difference Between Compost And Fertilizer

While compost and fertilizer may seem similar, the two have some key differences. Compost is a mixture of organic materials, such as leaves, grass cuttings, and food scraps, that have decomposed over time. Conversely, fertilizers may be liquid, pellets, or powder, offering specific nutrients to select plants. 

organic compost fertilizer

Compost provides a slow-release source of nutrients for plants and improves soil structure. Additionally, compost enhances microbial activity in the soil, which aids in plant nutrient uptake. 

On the other hand, fertilizers are concentrated nutrient supplements that provide specific elements essential for plant growth. Fertilizers, like granules or liquids, come in various forms and contain a precise blend of nitrogen, phosphorus, potassium, and other micronutrients. 1

While compost and fertilizer provide nutrients to plants, compost specifically improves soil health by increasing its ability to retain water and nutrients.

So, if you’re looking for an all-around soil enhancer that promotes healthy plant growth while improving soil quality, compost is the way to go. Alternatively, a good-quality fertilizer will work wonders if your soil is healthy but your plants need a quick boost.

What Is Compost

Compost is often called “black gold” for its ability to enrich the soil naturally. It’s a nutrient-rich mixture of decomposed organic matter, which results in a dark, crumbly substance that can be added directly to the ground in your garden.

compost vs soil

Many gardeners make their compost at home with household and garden waste, which is eco-friendly and relatively easy. Alternatively, it can be purchased cheaply from your local garden center or plant nursery. Compost is essential to create a strong foundation of healthy, nutrient-rich soil if you are serious about gardening and want the best out of your flowers, plants, or vegetables. 2

Benefits Of Using Compost

No matter what type of garden you have, producing healthy plants and vegetables requires the best possible growing environment, and using compost is vital to achieving this.

The main benefits of using compost are:

  • Nutrient-rich soil
  • Improved soil structure
  • Improved water retention
  • Increase microbial activity
  • Enhanced nutrient uptake by plants
  • Environmentally friendly
  • Long-term soil health
  • Low-cost (or free)
how to make compost fertilizer

Compost is a valuable source of organic matter, which contains essential nutrients that are slowly released into the soil, providing long-term nourishment for your plants or vegetables.

Unlike chemical fertilizers, compost improves soil structure, prevents erosion, and allows garden soil to retain water, saving you valuable time by decreasing frequent watering. Organic compost also helps suppress diseases and pests naturally without using harmful chemicals.

By using organic compost instead of chemical fertilizer, you not only support a healthier ecosystem but also contribute to sustainable gardening practices that prioritize environmental protection and long-term soil fertility. Best of all, making your compost at home is sustainable, accessible, and free. 3

Drawbacks Of Using Compost

While using compost can provide numerous benefits for your garden, it’s essential to be aware of the potential drawbacks.

The main drawbacks of using compost are:

  • Possibility of weed seeds
  • It may contain disease and pathogens
  • Home composting takes time to produce
best compost fertilizer

You must purchase high-quality compost or prepare your own correctly at home to reduce the chance of weed seeds becoming an issue within your compost pile. 

When organic materials are used to create compost, there is a chance that some weed seeds may survive the decomposition process and end up in your garden beds. These weed seeds can germinate and compete with your desired plants for nutrients, water, space, oxygen, and sunlight.

To remove this issue, use well-aged or properly heat-treated compost that has undergone a thorough decomposition process. You should also monitor your compost pile regularly, removing any weeds that do sprout or, better yet, leaving weeds entirely out of your heap.

The same is true for disease and pathogens. Any infected organic matter can contaminate a compost pile, transferring the disease to your garden and causing considerable harm to your plants and vegetables. Fortunately, these risks are significantly reduced when the compost has been properly prepared.

can compost replace fertilizer

The final drawback of using compost is that it takes time to create. Composting can take several weeks or even months before you have a suitable product that can be added to your garden soil.

There are multiple composting methods, and although hot composting is faster than cold composting, if you need it urgently, your best option is to buy high-quality compost from a nearby garden center while you wait for your pile to decompose. While it’s essential to consider the drawbacks of compost, you can see that the benefits of adding compost to your garden soil far outweigh any problems it may cause.

How To Make Compost

Compost is surprisingly easy to make, and because the materials used are already destined for disposal, in most cases, starting a compost pile of your own is entirely cost-free. You can create a compost pile anywhere in your garden without additional startup costs. However, if you can afford some initial expenses, the following items help make it easier. 4

1. A compost bin: Helps shield your compost pile from the elements while sealing in warmth for quicker decomposition.

2. A compost tumbler: Keeps the organic materials thoroughly mixed for even decomposition and cuts out the need for manual turning with a fork.

3. Compost activator: Contains a specific balance of microbes and chemical activators that kick-start the decomposition process quickly.

compost fertilizer benefits

Making compost requires collecting organic materials such as kitchen scraps, yard waste, and leaves. The process begins by layering the organic materials in your compost bin or pile. Maintaining a balance of carbon-rich (brown) and nitrogen-rich (green) ingredients promotes decomposition.

Add a little water to the pile so it’s damp but not soaking to help start the decomposition process. Although not always necessary, applying a compost activator will also speed up the process. An alternative to commercial compost activators is to make your own using a mixture of water, ammonia, and soda water with a high sugar content.

Depending on factors like temperature and moisture levels, you’ll have rich, dark compost ready for use in your garden within a few weeks or months.

Humble Tip:
If your compost pile is an open-air one, cover it with a lid, flattened cardboard box, or plastic sheet to protect it from the cold and rain and to deter animals or small rodents from accessing it.

Regularly turning your compost pile helps mix and aerate the materials, speeding up decomposition. Heat is generated as microorganisms break down the organic matter, potentially killing weed seeds and harmful pathogens.

What Is Fertilizer

Unlike compost, fertilizers provide a quick hit of nutrients directly to plants over a short period, which can be helpful if your soil lacks the required nutrients or if other plants and weeds compete for the already available nutrients. Fertilizers can comprise various components, depending on whether they are organic or synthetic.

should i use compost and fertilizer

While it can take time for compost to pass nutrients into the soil, fertilizers work immediately. They can be the difference between your plants and vegetables succumbing to a lack of nutrients or a healthy, thriving, and productive garden. 5

Benefits Of Using Fertilizer

Using organic or chemically synthetic fertilizers in your garden offers numerous benefits to plants and the garden’s overall ecosystem. Below are some of the primary benefits of using fertilizer.

Nutrient Supply

Fertilizers are formulated to supply vital nutrients like potassium, nitrogen, and phosphorus, which are crucial for optimal plant growth. These nutrients are necessary for plant cell growth, enhancing root development, and promoting flower and fruit production.

Increased Productivity

Nutrient-rich soil means healthier, more productive plants. Fertilizers create a favorable environment for plants to reach their full growth potential, resulting in higher yields for edible crops like fruits and vegetables and more abundant blooms in ornamental plants.

fertiliser compost

Soil Fertility

Fertilizers help improve soil fertility by replenishing nutrient content after each growing cycle, ensuring the soil stays nutrient-rich and fertile for future plantings.

Fast Action

Synthetic fertilizers, in particular, are quickly absorbed by plants due to their water solubility, which makes them effective when quick growth is needed.

Address Specific Soil Deficiencies

Fertilizers can be chosen and used to address specific deficiencies in the soil. For example, if soil testing reveals a lack of potassium, a fertilizer rich in this nutrient can plug the gap. At the same time, other amendments, such as composts, will deal with nutrient deficiency over the long term. 6

Incorporating fertilizers into your gardening routine can significantly improve plant vitality and contribute to a more productive and sustainable ecosystem.

composting benefits

Drawbacks Of Using Fertilizer

While fertilizers may provide many benefits, you should always be aware of the potential drawbacks, no matter how small.

Some drawbacks of using a fertilizer that you should be aware of are:

1. Environmental Impact: Fertilizer runoff can contaminate waterways, leading to algal blooms and harming aquatic life. 7

2. Soil Dependency: Continued use of synthetic fertilizers can create dependency, as the soil becomes less capable of sustaining plant growth without them.

3. Nutrient Imbalance: Overuse or improper application of fertilizers can disrupt the natural balance of nutrients in the soil, leading to nutrient deficiencies or toxicities, subsequently harming your foliage friends.

By choosing compost over synthetic fertilizers, you can promote healthier soil while minimizing environmental impacts.

Humble Tip:
It is important to understand that while fertilizers are essential for quick access to nutrients, compost offers a more sustainable and natural alternative, enriching the soil with organic matter and improving its structure and ability to retain moisture and nutrients naturally.

Types Of Fertilizer

Various types of fertilizer available in the market can cater to different soil needs. When choosing the right fertilizer for your garden, it’s essential to understand the differences between them.

how to make fertilizer

Organic Fertilizers

Organically derived fertilizers commonly come from animal matter, animal excreta (manure), and vegetable matter. 8

For instance, naturally occurring organic fertilizers encompass:

1. Manure: This includes cow, poultry, bat, or worm manure.

2. Compost: This consists of decomposed organic materials, like food and garden waste.

3. Bone meal: It’s a slow-release phosphorous source.

4. Blood meal: High in nitrogen and helps leafy plant growth.

5. Fish emulsion: Contains nitrogen and benefits leafy plants and vegetables.

why is composting important

Synthetic Fertilizers

Synthetic fertilizers are minerals produced through various industrial processes. These typically contain nitrogen, phosphorus, and potassium, the three primary nutrients plants require to grow properly. They can also provide secondary and micronutrients.

Some examples of synthetic fertilizers include:

1. Ammonium Nitrate: It’s a rich source of nitrogen.

2. Superphosphate: It provides a high amount of phosphorous.

3. Potassium Sulfate: A robust source of potassium and sulfur.

4. Potassium Chloride: Annually the most commonly used fertilizer for potassium.

5. Urea: An inexpensive form of nitrogen that’s exceptionally effective.

In addition to the macronutrients, i.e., nitrogen (N), phosphorous (P), and potassium (K), fertilizers also contain essential secondary macro and micronutrients, including calcium, magnesium, sulfur, and trace elements, referred to as full-spectrum fertilizers.

comparison of compost and fertilizer

Blended Fertilizers

There are also blended fertilizers, a mix of different fertilizers designed to provide balanced plant nutrition. Blended fertilizers may contain two or three major plant nutrients and can be customized according to the nutrient requirements of the specific plants or crops.

Key Takeaways About Fertilizers

Whether you use organic or synthetic, the key to understanding the nutrient requirements of your soil and plants is that excessive use can cause harm to both. Always test your soil health to identify what it needs so that you can select and apply the appropriate fertilizer.

Synthetic fertilizers are chemical-based and typically contain specific ratios of nitrogen, phosphorus, and potassium (NPK). These fertilizers can be tailored to meet the specific nutrient requirements of plants, but there may be some drawbacks, like leaching into water sources or causing imbalances in soil pH.

It’s important to consider all these factors when deciding which type of fertilizer to use to achieve optimal plant growth while minimizing environmental impact.

I highly recommend you take a few minutes to watch the video below. It expertly details the differences between compost and fertilizer and offers even more information about the nutrients fertilizers provide and what the numbers mean on their containers.

Additionally, you can also find some interesting information in this Fertilizer Fact Sheet from New Hampshire University.

When To Use Compost vs. Fertilizer

When deciding whether to use compost or fertilizer, it’s important for growers to understand their garden’s specific needs and those of their plants and ways to achieve them. Compost and fertilizer technically fertilize the soil, just in different ways.

nutrients in compost

While compost and fertilizers provide nutrients for plants, think of compost as more of an organic soil conditioner that improves the overall health and structure of the soil. Compost should be used regularly to keep soil healthy and full of nutrients. 9

Conversely, fertilizers are specifically formulated to provide concentrated nutrients for a plant’s immediate needs. If your flowers and vegetables look weary or your crops need to meet their usual standards, adding a high-quality fertilizer will quickly feed the soil with the missing nutrients.

Is Compost A Fertilizer

At this point, you may be wondering if compost is a fertilizer. Well, yes, it is! Compost is a natural fertilizer made explicitly from organic matter and chock full of nutrients that enrich your soil.

Although compost fertilizes the soil, keeping the two definitions separate is crucial to understanding their specific case uses. However, it’s important to remember that compost shouldn’t be used as a quick solution to amend nutrient-deficient soil on a short-term basis.

Humble Tip:
Fertilizers can be natural or synthetic and are specifically formulated for quick absorption to provide an immediate nutrient boost exactly when needed. So, while both compost and fertilizers serve the purpose of nourishing plants, they differ in their nutrient release rate and composition.

Can Compost Be Used Instead Of Fertilizer

Compost shouldn’t be used as fertilizer. However, regular use of compost may reduce or remove the need for using fertilizers. Compost can supply the soil with all nutrients required for healthy plant growth.

compost fertilizer meaning

Regular use of compost nourishes the soil and improves its structure, water retention, and drainage, allowing it to absorb and hold onto nutrients more efficiently.

While regular compost use can replace the need for fertilizers, the same cannot be said for everyday fertilizer use. Fertilizers only supply a short-term concentrated nutritional boost, become quickly depleted, and need to be reapplied. 10

Humble Tip:
Amending your garden soil regularly with quality compost is essential to prevent reliance on less ecologically friendly fertilizers and to provide you with a much healthier, natural garden for the long-term health and vitality of your green space.

Can Compost And Fertilizer Be Used Together

Compost and fertilizer can be used together; sometimes, it’s essential when neither can provide the necessary benefits alone. Regularly adding compost to your garden soil will often keep it healthy throughout the year, but some situations may quickly deplete your soil of its nutrients, or you may be growing crops that require more nutrients than the soil can provide.

is compost good for gardens

Adding some fertilizer is perfect if your plants or vegetables need nutrients from your well-composted soil. Compost and fertilizers work harmoniously, feeding the plants directly while the other has time to enrich and condition the soil.

When using compost and fertilizer together, it’s crucial to avoid over-application. Regular soil pH level testing will ensure the right balance is maintained. 11

Understanding your plants’ requirements and finding the right balance between compost and fertilizer will lead to success in any garden.

Are Compost And Fertilizer Environmentally Friendly

While compost and fertilizer can introduce essential nutrients into the garden, they impact the environment differently depending on their source and use.

compost vs fertilizer for garden


Compost is generally environmentally friendly as it is made from biodegradable waste materials. Composting these materials reduces the waste that would otherwise end up in landfills.

Conversely, composting requires attention to balance and moisture levels to prevent producing methane, a potent greenhouse gas. Also, using compost from conventional farms may introduce pesticide residues into otherwise organic gardens. 12


Fertilizers can significantly impact the environment, but it all depends on what kind of fertilizer you’re using. Organic fertilizers, like compost, are made from natural materials and are generally suitable for the environment. On the other hand, synthetic fertilizers are made in factories and often release many carbon emissions.

Not only that, but synthetic fertilizers can also cause water pollution if misused. When overused or washed away by rain into nearby rivers and lakes, they can create too many nutrients in the water. This can subsequently lead to harmful algal blooms that take up all the oxygen in the water and hurt fish and other aquatic animals.

is compost

Whether or not fertilizers are good for the environment depends on what kind and how you use them. It’s essential to be careful with fertilizers to minimize any environmental harm.

Below is an easy-to-read comparison table detailing the specifics of the impact of compost and fertilizer on the environment.

FactorsCompostOrganic FertilizerSynthetic Fertilizer
SourceOrganic WastePlant, Animal,
Mineral resources
Industry produced
using various
Production ImpactLow. Reduces
landfill waste.
Varies. Usually low
when responsibly
High. Carbon-
intensive production
and potential for
ApplicationCan be used liberally
without fear of
burning plants or
polluting waterways.
Should be used
responsibly, as too
much can impair
plant growth.
Should be used
carefully. Can burn
plants, and excess
can contribute to
pollution of
Water PollutionLow. Often improves
water retention and
Low if used properly.
Can contribute if
High; can easily
contribute to water
pollution, especially through runoff
Soil HealthImproves soil
structure and
promotes a healthy
Can improve soil
health; promotes
beneficial microbial
Does not improve
soil structure.
Constant use over
time may degrade
soil health.
Greenhouse Gas
Can contribute if the
composting process
is not properly
Relative low
emissions based on
the source materials
and production
Can be high due to
production and
BiodiversityPromotes the
presence of diverse
microbial life.
Naturally derived.
Typically does not
support biodiversity.
Overuse can
damage natural

It’s crucial to note that the environmental impacts of compost or fertilizers may vary greatly depending on many factors. The way they are produced and applied, the materials used, the location and climate of the garden or farm, and so on. Using and managing them responsibly is essential to minimize their environmental impact. 13


Hopefully, you better understand the differences between compost and fertilizer and when to use each. Knowing when to use compost or fertilizer is crucial for optimal plant health. 

Compost is excellent for improving long-term soil health and sustainability, while fertilizers are best used to target specific nutrient deficiencies or promote rapid growth.

While compost can be used instead of fertilizer in some cases, it doesn’t provide the same quick-release boost as fertilizers. However, combining both compost and fertilizer can create a powerful synergy that ensures your plants receive a well-rounded nutritional balance.

When it comes to environmental friendliness, compost takes the lead. It reduces waste by recycling organic materials while minimizing chemical runoff into water sources. Fertilizers should be used responsibly to prevent pollution but still play an essential role in meeting high crop demands.

How do you use compost and fertilizers in your garden to take your operation to the next level? We’d love to hear about your achievements, so take a moment and leave us a comment below! 


  1. National Library Of Medicine, National Center For Biotechnology Information – Effect Of Compost And Inorganic Fertilizer On Organic Carbon And Activities Of Carbon Cycle Enzymes In Aggregates Of An Intensively Cultivated Vertisol
  2. Wikipedia – Compost
  3. IOP Science – Composting: A Better Alternative Of Chemical Fertilizer
  4. United States Environmental Protection Agency – Composting At Home
  5. United States Department Of Agriculture, Economic Research Service – Fertilizers & Pesticides
  6. Penn State University, Extension – Fertilizer Basics
  7. National Institute Of Environmental Health Sciences – Algal Blooms
  8. Utah State University, Yard And Garden Extension – Selecting And Using Organic Fertilizers
  9. University Of Maryland, Extension – Organic Matter And Soil Amendments
  10. CAES Newswire – Compost Enriches Soil – But Doesn’t Replace Fertilizer
  11. University Of Maryland, Extension – Garden Fertilizer Basics
  12. National Library Of Medicine, National Center For Biotechnology Information – How The US Economy And Environment Can Both Benefit From Composting Management
  13. ASA Journals – Environmental And Economic Trade-Offs Of Using Composted Or Stockpiled Manure As Partial Substitute For Synehetic Fertilizer

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