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To produce healthy fruits and vegetables, you need soil rich in nutrients. These nutrients include nitrogen, phosphorus, and potassium. Worm castings and bat guano are both excellent sources of these organic nutrients. They enhance soil texture, drainage and are a commendable soil conditioner.

The nutritious value of both worm castings and bat guano depends on what the worms and bats eat. For example, their diets determine whether the manure has adequate nitrogen, phosphorus, and potassium for boosting. While the main difference between these two fertilizers is nutrition, there are a few other significant differences. This article will elaborate further on worm castings vs. bat guano and which is better.

Worm Castings

Worm castings, otherwise known as vermicast or worm poo, are organic manure derived from earthworm excretion. The worms produce neutral castings with a pH of seven through a process called vermiculture or vermicomposting.  After worms feed on compost, they digest and later excrete rich waste, which improves soil performance. 

The manure has a football-like shape and improves soil aeration, drainage, and water retention. Additionally, the castings do not have a strong smell.  Besides that, worm castings act as pesticides and help keep off harmful insects like aphids and spider mites.

Worm casting has an NPK (Nitrogen-Phosphorus-Potassium) rating of 1-0-0, which means that it contains nothing but nitrogen. It has approximately four to five percent more nitrogen than garden soil. Furthermore, worm castings come in either tea or solid form that is then added to your garden, directly to your plants. This type of organic fertilizer is compatible with most plants, as it doesn’t burn. Additionally, earthworm castings contain beneficial microbes that help plants grow strong and fight diseases.


  • Enhances soil aeration
  • Adds microorganisms to the soil
  • Reduces soil erosion
  • Helps the soil to retain moisture
  • 100% organic
  • Aids in nutrient absorption
  • Keeps off pests and diseases


  • More expensive than chemical fertilizers
  • Difficult to produce in large quantities

Bat Guano

Simply put, bat guano is bat excreta or feces obtained from fruit and insect-feeding species of bat. Bat guano acts as high-quality natural fertilizer, containing exceptionally high levels of nitrogen, phosphorus, and potassium. It is highly recommended because it doesn't have a strong odor.

Furthermore, bat guano aerates the soil, enhances drainage and texture, and improves soil fertility. With the high phosphorus levels, guano is suitable for root development and keeping plants healthy. The majority of bat guano may be obtained from caves, usually located in mountains that host a large population of bats.


  • 100% natural
  • Has high concentration
  • Improves soil fertility
  • Enhances moisture retention
  • Damages nematodes
  • Helps plant to absorb nutrient
  • Has antifungal properties


  • Also more expensive than chemical fertilizers
  • Difficult to attain

Similarities Between Worm Castings and Bat Guano

Organic Fertilizers

Bat guano and worm castings are excellent alternatives to chemical fertilizers. This is because the worms and bats feed on compost, and fruits and insects, respectively. Therefore, the manures produced are purely natural. 


Bat guano improves soil performance and aeration. Similarly, worm castings enhance drainage and texture. 


Both bat guano and worm castings can be used for top-dressing or produced as a tea to spray directly on plants.

Humic Acid

Like worm castings, bat guano contains humic acid. The acid acts as a catalyst that helps crops absorb essential nutrients. As a result, the crops grow fast, flower, and produce fruits in less time.

Differences Between Worm Casting and Bat Guano


You can find bat guano in caves located in tropical mountains, while worms make castings from anywhere. Harvesting guano and bringing them to users is complicated and tedious. Consequently, the price of bat guano is four times that of worm castings.

Nutrition Value

Unlike worm castings, bat poop has a relatively high nutrition value, and the NPK composition of the fertilizer represents this. While worm casting has an NPK value of 1-0-0, commonly used bat guano has 10-3-1, meaning that it is usable at different stages of plant growth.


Worm castings have a high percentage of nitrogen and can be used for top-dressing, making them suitable for direct application on the ground before planting. This is because there is fast absorption through the roots.

On the other hand, bat poop comprises relatively all nutrients suitable for growing healthy plants and roots development. However, the type of guano determines the percentage of a specific nutrient. In an instance where you apply one cup of bat guano, you might require a gallon of earthworm castings for the same effect.


Bat guano comes from bat droppings found in caves. The bats eat insects and fruits, making the manures harvested rich in proteins necessary for growing plants. On the contrary, earthworms feed on compost and excrete castings.


The process of acquiring bat droppings is long and tedious. Also, the species that produce guano are mostly found in caves in Latin America. Therefore, you will need to incur the extra cost to import if you don't live near those places. However, worm castings are found in any place with earthworms feeding on compost. The downside of worm casting is that it only comes in small quantities.


With the rise of diseases and health conditions caused by poor eating, it is evident that organic fertilizers are the way to go. Health professionals are discouraging the consumption of GMOs. As a result, farmers are now implementing natural fertilizers to grow food crops.

That said, you might be considering worm castings vs. bat guano as fertilizers for your garden. The advantage of using either of these fertilizers is that the crops grow healthy and free from pests and soil-borne diseases. Worm castings, like Simple Grow,  and bat guano are some of the best examples of high-quality manure since they contain nitrogen, potassium, and phosphorus. They are suitable for soil conditioning, aeration, moisture retention, drainage, and texture enhancement.

While gardening, you can mix the soil with either these manures beforehand or use their tea on already grown plants. It is essential to use the correct measurements so that you don't oversaturate or burn your crops.

Grow Bigger Plants with Simple Grow

Do you wish your plants would grow bigger? Was your garden less than it should've been last year?

If you're tired of growing puny vegetables and fruits, it's time for an upgrade...Simple Grow Worm Castings!

What are worm castings? Another term for worm manure. Why would you want to use it in your garden, raised beds, and house plants? Because it makes them grow bigger, faster and healthier...with no chemicals!

How do worm castings do this? It's like giving your plants a powerful multivitamin with everything they need to grow. Trace minerals, nutrients, and most importantly...worm castings are chock full of beneficial microbes. Why does that make a difference?

In recent years, we've learned the importance of gut bacteria for humans and know that it impacts so many different parts of our health. The same thing applies with worms. Gut bacteria from the worm's digestive tract gets into the soil from the worm castings and promotes plant health. Plants have a symbiotic relationship with the microbes from the worm's digestive tract. Plants respond to it and grow really big...really fast!

If you've never tried worm castings before, you owe it to yourself to give them a try. Instead of using traditional chemical fertilizers from the big box store, why not try fresh, certified organic worm castings this year? You'll be able to grow bigger, healthier plants that you actually can feel good about eating. 

Take advantage of our special bundle sale on 25lb bags today!


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