Guano: From The Bat Cave To Your Gardens

This article originally appeared in Garden Culture Magazine US20.

For thousands of years, from the time of the Incas through modern-day, bat guano has been used in farming worldwide. Within the growing industry, bat guano is often sold as a flowering-stage booster applied to increase the size and weight of fruits and vegetables. Below is a better explanation of all the unique benefits gained from using bat guano as fertilizer from seed through harvest, which may help you understand where the expression “Bat Poop Crazy“ originated from.

Guano Around The World

Bat guano is naturally sourced from regions of the world that have climates which are specific to bats. These regions extend from South America to Central America and beyond, including the tropics of Mexico, Indonesia, China, Japan, Jamaica, Thailand, Peru, Australia, and many more. Depending on what the bats eat, as well as what time the bat guano is mined, determines the available amount of primary and trace elements and its microbial count. Most commercially sold bat guanos are usually higher in phosphorus and low in nitrogen and potassium.

The ratio on a tub of powdered guano will typically read N-P-K of 0-10-0, whereas freshly mined bat guano may have a considerably higher nitrogen count. Mexican bat guano can read an N-P-K of 10-1-2, meaning that using bat guano solely for flowering, can often be misleading. Knowing what diet the bats have, and what part of the world the guano came from, will allow you to better understand how this humic fertilizer is highly beneficial throughout the life cycle of any plant.

The Microbe Count

If you are familiar with beneficial bacteria and fungus, then you will likely be aware of how microbial colonies can determine the integrity and functionality of a plant’s performance. Microorganisms play a vital role in soil culture and will form a symbiotic relationship with the substrate and plant roots. A single ounce of bat guano in dry powder form contains billions of bacteria. This bacteria is highly beneficial and will improve uptake delivery of nutrients to the plant. Chitinase found within the guano, produces microorganisms which can control insect and nematode count.

Typical Analysis of Bat Guano

Each source can have a different nutrient composition, determined by the time it was harvested from the cave, and what the bats choose as a diet. You can easily find guanos online which are rich in nitrogen (10-3-1) or high in phosphorus (1-10-1). In addition to bat guano, seabird guano is also very effective and available as high nitrogen and phosphorus feed (12-8-1).

Sourcing different bat guanos which can complement the growing stage, as well as boost flower production, can easily be done and will allow your plants to benefit fully. Seedlings require nitrogen, phosphorus, and many other trace elements to function and grow into healthy young plants. Powdered bat guano will act as a slow-release humate that will leach micro and macronutrients back into the growing medium. Roots will absorb the readily available phosphorus, which in turn, will be aided by a colony of beneficial microorganisms.

Enzymes Found in Guano

Using bat guano as an enzyme is often overlooked. Found deep within the guano is an enzyme named chitinase. This highly beneficial enzyme performs the role of converting humic matter into simple forms of sugar that the plants can utilize with ease. Chitin is what makes bat guano unique regarding its use as an enzyme, which is one of the most abundant sources of complex carbohydrates. It is also used to convert shrimp, crabs, crustaceans, and exoskeletons into fermentable forms of sugar.

In the city of Fez in Morocco, famous for their production of animal skins and leather, they have used pigeon guano as a technique for thousands of years. Using pigeon guano and water, they can wash, treat, smooth-out, and color leather, which has earned them the title of Europe’s primary leather producer, exporting to Spain, France, and India.

A Booster During Flowering

When plants are producing fruits or veg during the blooming phase, adding bat guano can be extremely beneficial for increasing plant vitality and vigor. An instant reaction can take place after feeding bat guano to plants, which may result in the leaves growing at 45-degree angles. Adding bat guano to your grow medium will supercharge the root zone and over time, increase flavor, aroma, biomass, and final weight.

For the flowering stage, bat guano with a 1-10-1 analysis is better advised as a supplement to another nutrient high in potassium. Bat guano can be applied in different ways, such as brewed into an organic compost tea or as a dry powder topdressing to act as a “leaching agent” with every watering.

Bat Guano Tea

The best way to fully utilize bat guano is to brew an aerated compost tea. This simply means adding a source of powdered or liquid bat guano into a bubbling water source. The principle behind the aeration is to promote the aerobic bacteria which depend on oxygen to survive and transform millions of spores into billions of spores. Along with the other benefits that the plants will enjoy, adding a bat guano compost tea will provide a supercharged growing medium.

Guano tea also ensures there is a state of perpetual humification and protects the growing medium from nematodes and insects. Making bat guano tea can produce a severe odor which is not pleasant. Thoroughly research the process of making an aerated tea before brewing your own, and be sure to cover all the basics concerning odor control and microbial production.


Using bat guano is an eco-friendly and organic solution to better farming. Rich in nutrients and highly beneficial to soil culture, bat guano can be used as a powdered application or as a liquid drench, which can also be applied as a foliar feed or directly to the growing medium. Using bat guano will improve the health and vitality of plants, increase root mass and nutrient uptake considerably, improve terpenes and flavor, increase the final harvest weight, and may improve potency. Using bat guano is cheap, extremely effective, and one way to make the most of our natural resources.

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1 Comment
  • Ms'Barbara H. Evans says:

    I have tried to attract bats to my yard but to no avail. I have a bat house but NO bats. What can I do?


Stoney Tark is a freelance writer with over 15 experience in the canna industry. Specialising in plant science, tutorials, how-to-guides, top tips, microbiology, breeding and all fundamentals cannabis-based. Living in Amsterdam and the resident writer for Soft Secrets and Garden Culture Magazine.