Worm Castings Vs. Compost: Which One to Choose?

Worm castings vs compost
When it comes to worm castings vs. compost, there are more nutrients and humus in worm castings, which improves moisture and aeration. However, buying bulk is usually more expensive, and DIY vermicomposting is not a walk in the park.

Worm Castings Vs. Compost

Both worm castings and composting can be low-maintenance. However, they still require effort to generate a high-quality end product.

Worm castings take a few months to make, but if you do it right, you’ll have finished compost in just 2 to 3 months.

Vermicomposting has size limits. Many home systems are for moderate kitchen waste. Composting handles volumes of trash like garden trimmings, leaves, grass clippings, and dry leaves. 

However, worm composters are more compact. Because of this, vermicomposting is a great option for those with limited yard space.

When properly maintained, neither of these processes produces any odor. Aeration is the primary driving factor here.

Is Worm Castings the Same as Worm Compost?

Worm compost (vermicompost) and worm castings are not the same. So, what precisely do these phrases mean?

Worm castings are also referred to as “worm manure.” They are produced when worms feed and break down organic matter.

Worm compost‌ combines worm castings and organic waste that has been partially broken down.

Waste food and bedding are broken down many times on a worm farm. The final “worm castings” will always contain a mix of castings and organic material.

Anyone who tells you they’re selling you “pure” worm castings is lying!

What Is the Difference Between Compost and Worm Castings?

Soil amendments made from vermicomposting and compost have long been beneficial. But what distinguishes these two products?

FactorsWork CastingsCompost
What is itWorm poopDecomposed organic matter
Plant nutrient availability Higher nutrient availabilityFewer nutrients than in worm castings
Soil aeration and porosityMediumHigher
Capacity to hold waterGoodHigher
PH levelsNeutralAcidic but becomes neutral as it matures

What Are Worm Castings?

Vermicasts and vermicompost are both names used to refer to worm castings. Worm castings result from the decomposition process that occurs in different ‌worms. To put it another way, they are worm poop.

Worms that consume plant material excrete nutrient-rich feces that are high in nutrients, which are water-soluble and have few pollutants.

Worm castings are also high in “humus,” a mushy carbon-based compound that aids in keeping the material moist and aerated.

Worm castings are an ideal option for smaller vegetable gardens since they are abundant in nutrients and valuable for plant moisture and aeration.

Worm castings vary in quality and cost more than manure and other soil amendments.

What Is Compost?

Compost is a compacted heap of humus decomposed from organic matter. You can add grass clippings and other decaying plant waste to a compost pile, where they are broken down by bacteria, fungi, worms, and other microorganisms which feed on decomposing materials.

One of the best aspects of compost is that one can prepare it at home by adding vegetables and other organic materials.

Let’s compare the individual qualities of compost and worm castings.

Plant Nutrient Availability 

Worm compost has more nutrients and higher nutrient availability compared to regular compost.

It comprises N-P-K (nitrogen, phosphorus, and potassium) and secondary nutrients like calcium and micronutrients. 

Worm castings have a more excellent N-P-K ratio than compost. These water-soluble nutrients are readily available for plants.

Compost releases nutrients slowly. Not all nutrients are available quickly. Neither is better because of this disparity, though:

Slow-release organic fertilizers are great for long-term nutrition. Fast-release fertilizer boosts plants quickly.

Worm castings are nitrogen-rich. Since most soils lack nitrogen, worm compost is beneficial.

Aeration and Porosity

Organic matter boosts oxygen circulation in the soil. Compost or worm castings’ texture and structure produce air spaces that allow plants to “breathe.”

Mature compost contains a lot of humus. It has a spongy fibrous feel and is black and crumbly. However, most composts have a more coarse consistency than worm castings do. This structure’s coarse texture improves the aeration of the soil.

As time passes and the compost decomposes more, the humus is left behind in the soil, where it continues to enhance the soil structure.

Worm castings are dark and fine-textured. Worms breaking down organic materials produce finer compost than regular compost. The humus from worm castings is approximately 50% more than ‌standard garden soils.

Capacity to Hold Water

The water-holding capacity of vermicompost is exceptionally high. The small aggregates created by the worm castings help strengthen the soil’s resilience to compaction and erosion, increasing water retention simultaneously.

Compost can hold 200 times its weight in water. Due to its high humus content, worm castings may hold more water.

Pathogen Reduction

Compost and vermicompost both promote plant health by minimizing the occurrence of plant pathogens. That is because of the beneficial microbes found in worm castings and compost.

Changes occur in the surrounding microbial population of a plant when you add amendments like worm castings or compost into the soil.

It changes the composition of the microbial community such that more of the kind that inhibits the growth of certain diseases are present.

Plant Growth

Vermicompost contains PGRs (plant growth regulators), which could boost plant growth. 

Compost and vermicompost both contain properties and nutrients that promote plant growth.

PH Levels

Worm castings have s pH of 7, meaning neutral. Compost has a pH of 6 to 8. Compost is first acidic, but as it matures, it becomes more neutral.

That suggests that worm compost may need to be modified for usage with plants that prefer acidic soils.


Regular compost is often cheaper than vermicompost. Probably constructing your own is preferable.

What Percentage of Vermicompost Is Castings?

Vermicompost isn’t 100% worm castings. Most worm castings or compost include 20 to 50% organic matter. That depends on how worm castings are made and how long we leave worms to decompose organic waste.

You might leave worms for months to ensure that the organic matter is “processed” multiple times. 

Eventually, you may get worm castings close to their purest form. Gardeners ‌believe this “vermicast” has been overworked and is hence of lower nutritional value.

What Makes Worm Castings Appealing?

Worm castings are desirable because of the worms themselves. The organic materials that it consumes are refined while being digested.

Trace elements, minerals, and nutrients are converted to their most useable form. Worm castings have a pH of 7.0, which is ‌neutral.

Benefits of Using Worm Casting

Some benefits of using worm casting include:

  • Worm castings are a natural fertilizer that is low in toxicity, highly effective, and provides plants with vital nutrients. Using worm castings helps plants grow stronger, larger, and produce more vegetables, fruit, and flowers. It increases plants’ resistance to drought, pests, heat, pathogens, and other problems. 
  • Earthworm castings are hard to “overdo” because they are slow-release. But a small amount can go far!
  • Organic agriculture relies heavily on fungi and helpful bacteria in the soil food chain, which worm poop provides in spades.
  • Worm castings help improve the structure of the soil. They do this by increasing aeration, enhancing drainage, and boosting the soil’s ability to keep moisture.
  • You’re supporting a closed-loop system by sponsoring worm farms or keeping a worm compost bin. Vermicomposting lowers garden and food waste and provides free organic fertilizer


Discovering composting as a way of life or even better, as nature’s way of recycling, Ana dedicates her time to trying out new methods of composting at home. Her goal is to share everything that she’s learned in the hopes that it will help others discover the amazing rewards of composting.

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