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Advanced Techniques

How To Supercharge Cannabis With Bat Guano

How To Supercharge Cannabis With Bat Guano

Nature provides. Time and time again, this belief is proven especially in horticulture. While science brought astonishing advancements to gardening, man-made substances are yet to equal or outmatch non-synthetic materials.

Bat guano is an exceptional example. A widely known natural fertilizer, its high levels of essential nutrients make it an ideal product for organic growing. The plant food also boasts of beneficial properties useful in different sustenance applications. Best of all, growing floras bursting with health is a lot less complicated with its easy to employ ready-to-use mixtures.

Bat Guano In Cannabis Cultivation

Although not among the most well-liked member of the animal kingdom, bats play a crucial role in the ecosystem. Some types help control the insect population while others contribute in the pollination of floras. Such functions in the biological community ensure the various production and population of both plants and animals. The flying mammal does not stop there, though, as it also bestows significant benefits in cultivation through its ‘by product’.

The accumulated fecal matter, known in the horticulture scene as “guano” , builds up beneath roosting caves. It contains high levels of vital nutrients such as nitrogen, phosphorus, and potassium, making it widely popular among organic growers. On top of that, the contrasting diet preference of different bat species allows for a degree of diversity in manures thereby affording various uses and applications. Other sources of guano are coast-dwelling seals and seabirds.

History Of Guano

Guano or “wanu” in the ancient Quechuan language has been used in cultivation since the ancient times. For over 1500 years, it was regarded as a highly-prized fertilizer by the Andean people of South America. The rulers of the Inca empire even restricted access to the valuable material and implemented death penalty to anyone who disturbs the guano-producing wildlife and its habitat.

During the 19th century, the ordure became a reason for war as well as expansion. In 1864, Spain seized the guano-rich Chincha Islands that belonged to Peru. Consequently, it led to the two-year-long Spanish-South American War. Then, a decade after the conflict ended, the US Congress passed the Guano Island Act which permits Americans to assert ownership of unclaimed islands. More than 50 were claimed in the Caribbean and the Pacific.

Apart from its use in agriculture, the natural material was also employed in making gunpowder and explosives due to its abundant saltpeter (Potassium Nitrate) content when in dried form. The United States utilized it in the War of 1812 against the United Kingdom. Then, a couple of decades after, the deposit was again put to service by the Confederacy in the American Civil War.

Chincha "Guano" Island

Nutritional Composition

Like all living organisms, plants need nutrients to survive. To reap its full benefits, the plants need balanced, adequate nutrition to thrive. And, this is where the bat guano is useful. It contains both macro and micronutrients essential for healthy growth, development and fruit production. Moreover, its nutritional profile depends on the diet of a particular bat species. For instance, insect-eating bats produce excrement that contain a high level of nitrogen while fruit-feeders yield high phosphorus feces. Such range in nutritional value makes it relevant in all growth stages.


To achieve optimal growth, development, and the ability to self-repair, life forms need different macronutrients or the required nutrients in large amounts. In the case of cannabis, these are nitrogen, phosphorus, and potassium (NPK).

  • Nitrogen (N) –The main component of chlorophyll and amino acids, which ensures a healthy above the soil maturation such as the burgeoning of stems and leaves.
  • Phosphorus (P) – It is an essential element for photosynthesis that also allows root growth as well as favorable resin production.
  • Potassium (K) –A bacteria and mold resistance booster, it also makes stems and branches robust. The mineral plays a vital role in the use of air and light as well.

Macronutrients are essential to every phase of plant growth. However, different stages require varying proportions and combinations of NPK. Bat guano with high nitrogen content is ideal during the vegetative stages. On the other hand, a phosphorus-heavy load is best applied while budding.


The needed vitamins and minerals in minimal quantities are referred to as micronutrients. Despite the amount difference, micros are as essential as the macros as they can promote or deter an organism’s well-being and functions. Among the several compounds found in bat guano that ensure vigorous growth in cannabis are:

  • Boron (B) –A mineral that contributes to the cell wall, fruit, and seed development along with the calcium absorption.
  • Calcium (Ca) –An element that preserves cell structure especially in the root system and facilitates photosynthesis as well as the absorption of other nutrients.
  • Iron (Fe) and Manganese (Mn) –Both functions in the enzyme systems and stimulates the production of chlorophyll.
  • Sulphur (S) and Zinc (Zn) –They are building blocks of proteins and enzyme production.
  • Magnesium (Mg) – The key to the absorption of light or sun energy.

Horticulture Applications

Bat guano boasts of a long history as a natural fertilizer and is most known as such. However, with such beneficial makeup, it was not meant to remain of singular application. These days, the manure is popularly used in three different, purposeful ways.

Bat guano fertilizer
  • Fertilizer.Compared to other manures, bat guano is much more potent. Hence, it must be applied in smaller amounts. The excrement can be worked into the soil, used as a top dressing, or made into a tea for some deep root feeding.
  • Pesticide. With its pest control qualities, bat guano can be an effective fungicide when applied to plants through the leaves.
  • Soil Enhancer. Bat guano enhances the quality and performance of the soil. It can bind overly fluffy soil or loosen dense base, and also increase water retention. Since the excreta cannot be easily drained out of the medium, its effects last longer than most chemical fertilizers.


The potent growing material is well-regarded in organic and even conventional growing. It is fast-acting, virtually odorless, adaptable in every phase of plant growth, and produces long-lasting effects. Those positive features also come with these benefits:

  • Provides essential nutrients to the cannabis
  • Improves overall soil health by providing beneficial microflora and microbes
  • Acts as a pH adjuster for better nutrient absorption
  • Supplies nutrients for prolonged periods through its slow-release quality
  • Accelerates the decomposition of the exhausted materials and activate compost
  • Removes toxic elements in the soil
  • Controls and prevents nematode attack or infestation
  • Yields more flavorful buds as compared to synthetic counterparts


The bat manure’s ability to nourish and protect cannabis plants is exemplary. Apart from its hefty price tag, finding the natural product’s downside proves difficult. To grasp its seemingly unnoticeable flaws requires looking at the bigger picture.

Ecological Impact

Improper bat guano harvesting destroys the natural richness of an area. As the demand for the product increases, reports of unacceptable mining activities also shoot up. Natural habitats, nesting grounds, and sources of food have been destroyed or heavily disrupted. Some of the adverse results are:

  • Disruption of the bat population caused by cave structure changes that affect the airflow.
  • Diminishing biodiversity due to the use of pesticides to kill and drive away cave-adapted invertebrates that live off the high-valued excrement diminishes the biodiversity in the area.
  • Loss of paleoclimatic records and evidence of environmental changes naturally collected by the feces accumulation for thousands of years due to digging as well as the use of explosions to gain better access to the manure deposit.

Harmful harvesting is not limited to bat feces mining. The past mining for the abundant accumulation of seabird guano also caused concerns in different places such as the Great Barrier Reef. The activities brought about many significant changes in the geomorphology of at least 10 locations including Raine and Lady Elliot Islands. Modifications were so severe that very little of the places’ original vegetation and surface material remained.

Apart from the physical alterations in the landscape, guano mining also left a depression in the center of Raine Island. To date, the removal of the manure deposit is considered as “the most devastating impact on any of the islands of the outer Great Barrier Reef.” It also affected the female marine turtles that come ashore to lay eggs. Unfortunately, it’ll take hundreds of years for such spoilation to recover. Nonetheless, a promising campaign to rehabilitate the islet has already been launched.

Health Hazards

Workers in guano caves are most susceptible to Histoplasmosis due to their constant exposure to bats and bat dung. Caused by a fungus named Histoplasma capsulatum, the disease is airborne and can be transmitted by spores from bat droppings and contaminated soil. The infections are often mild with minor influenza-like illness or no symptoms at all. However, there are also some cases of high fever, pneumonia, blood irregularity or even death.

Individuals should not harvest bat feces to create a personal stash of guano fertilizer as excrements may be hazardous if untreated. For safety reasons, it is best only to use commercial bat guano products as such merchandises have undergone rigorous processes to be free of any viruses.

Using Bat Guano For Optimal Growth

To supercharge cannabis plants, utilize the powerful manure as a nutrition source, protective agent, as well as a soil supplement. As always, purchase commercial bat guano and simply make different formulations using it.

Bat Guano Fertilizer

Bat guano can be applied to plant cultivation in various ways as it comes in liquid, pellet, and powdered form. It can be directly blended to the soil, watered on cannabis as a compost tea, or worked into the base by digging it in.

Make A Fertilizer Tea

Watering-in bat guano as tea is the most convenient way of incorporating the material in cannabis growing. It also does not require the use of any difficult to access component.


  • 1 tablespoon of Bat Guano
  • 1 liter of Water (Warm and Non-Chlorinated)


  1. Add the guano while stirring the water.
  2. Let it sit overnight. If using city chlorinated, allow the chlorine to dissipate by leaving it in an open container for the duration.
  3. Apply the final product directly to plants. To use as a foliar spray, apply the tea using a fine mist sprayer before dusk or early morning. For root application, spray it at the root area and water properly to clear its way through the roots for proper absorption. Note that it is critical to apply the tea immediately as it loses its nutritive benefits quickly.

Put Together An Organic Soil Mix

Do not cut corners when growing cannabis. Always use the best materials to ensure optimal growth. Of course, this starts with employing a balanced, excellent-quality soil mix as a base.


  • 8 Large bags of High-Quality Organic Soil with a Coco and Mycorrhizae
  • 25-50 lb. Organic Worm castings
  • 5 lb. Steamed Bone meal
  • 5 lb. Bat Guano
  • 5 lb. Blood meal
  • 3 lb. Rock Phosphate
  • 3/4 cup Epson Salts
  • 1/2 to 1 cup Sweet Lime (Dolomite)
  • 1/2 cup Azomite (Trace Elements)
  • 2 tbs Powdered Humic Acid


  1. If renting a cement mixer is not possible, use a tarp and place a few bags of the base soil.
  2. Add the powdered nutrients in the center of the mound. Cover with more base soil.
  3. Add the bat guano and put more base soil.
  4. Continue to layer the mix with alternating powdered nutrients and base soil until everything has been added.
  5. Turn the mixture using a shovel until thoroughly blended. Once done, the soil mix can already be used.

Use As Soil Amendment

Amending the soil with bat guano improves its overall quality and function. The excreta enhances the base’s drainage, aeration, structure, water infiltration, water retention, and permeability to provide the cannabis roots a better environment.


  1. Add powdered bat guano to the soil. Use 5 lb. for every 100 sq. ft. of the medium.
  2. Dig into the surface of the soil or mulch gently to incorporate the manure into the base. Sprinkling and leaving the powder on top of the medium will cause it to dry, clump, and be ineffective.
  3. Water-in the to activate the soil-guano fusion.

The Unexpected Gift

Bat guano is an all-rounder. The macro and micronutrient-packed fertilizer boosts not just plant growth but also soil quality. With numerous applications, there is no doubt why the manure is highly sought after in both commercial and home cultivation. For a thriving cannabis not bathing in synthetic elements, the unexpected source of sustenance and support is nature’s gift.

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