By Adam Parsons Reviewed by: Mr José

What is guano?

Bats are very social creatures. These adorable little mammals form large colonies that share the same cave for generation after generation. Over the centuries, dunes of excrement build up on the floor of the roost cave, becoming compost. What results is guano, called “wanu” by the ancient South American Quechuans.

Guano is a plant superfood that is rich in the three essential plant nutrients, nitrogen, phosphorus, and potassium. Nitrogen ensures vigorous and verdant growth during the vegetative cycle. Phosphorus supports healthy flowering and root growth. Potassium ensures sturdy trunks and branches. Guano also contains a complete range of micronutrients for overall healthy plant development.

The diet of the particular bat species can alter the nutrient profile of the guano. Insect-eating bats produce a guano that has a high nitrogen content. This makes it ideal for fertilising during the vegetative phase. Fruit-eating bats produce a guano that has a high phosphorus content. This is best for use during the flowering phase when cannabis has a higher demand for phosphorus.

Brands offer nutritional products designed for specific stages of the growing cycle. For example, some companies offer powdered products with an NPK value of 8-1-1 or 7-3-1. These formulas contain higher levels of nitrogen, which helps to fuel leafy growth during the vegetative phase. Other products are focused on feeding plants during the flowering phase. These formulas typically contain NPK values of 0-10-0 and 0-12-0, as cannabis plants require higher levels of phosphorus to form healthier and bigger buds. 

RQS Bat Guano: A Natural Source of Phosphorus

Bat guano fertiliser is a natural source of phosphorus and organic matter that feeds flowering plants and the soil simultaneously. The nutrient profile of this product varies slightly from batch to batch, but every 500g pouch contains a minimum NPK value of 1:10:1. This quantity of key macronutrients helps flowering cannabis plants to thrive by boosting their rate of development, optimising flower formation, and facilitating photosynthesis.

What Macronutrients Are Found in Bat Guano?

Cannabis plants require access to an array of nutrients to reach their full potential. Aside from macronutrients, they also depend on several micronutrients to survive and thrive. Although they need these substances in smaller amounts, they are no less important. Micronutrients enable cannabis plants to carry out important physiological functions, from cell wall building to photosynthesis. Explore the benefits of some of the micronutrients found in bat guano:

Boron (B)

This element contributes toward cell wall formation, the integrity of cell membranes, and the movement of sugars to the growing parts of plants.

Calcium (Ca)

As an essential plant element, calcium plays a key structural role by assisting in the development of cell walls and membranes. The element also plays a role in the response to biotic stress caused by pathogenic viruses, bacteria, and fungi.

Iron (Fe)

Iron contributes toward the production of chlorophyll, the green pigment involved in the conversion of light to sugar.

Manganese (Mn)

This brittle metal plays a role in several biological systems in plants, including photosynthesis, nitrogen use, respiration, and root cell health.

Sulphur (S) and zinc (Zn)

These key micronutrients play a vital role in protein building, as well as the creation and activation of important enzymes.

Magnesium (Mg)

Magnesium sits at the heart of the chlorophyll molecule. Without this metal, plants wouldn’t have the machinery to conduct photosynthesis.

Guano is ideal as an organic soil amendment, either dug-in around the plant or watered-in as a tea. It makes an ideal backbone to any soil recipe, and has the unique characteristic of never burning plants, unlike most nutrients. Fruits and vegetables grown with guano are more flavoursome and resistant to disease. It is the same with cannabis. Guano will “mango” or sweeten the bouquet and flavour of buds when dry.

How quickly does bat guano work?

Bat guano doesn’t work instantly. As it’s a natural source of phosphorus and rich in organic matter, soil microbes must first break down this substance to make phosphorus molecules available to plant roots. After adding bat guano fertiliser to your soil, it takes around two weeks for bacteria and fungi to do their thing and strip it down.

However, this slow-release mechanism benefits plants in more ways than one. By feeding the soil, you’ll improve the quality of the microbial life within, which has a knock-on effect on plant health. Second, a slow but steady flow of phosphorus feeds plants in a balanced way over time, erasing the risk of nutrient burn and toxicity.

If you’re seeing signs of phosphorus deficiency, you’ll want to get your plants fed as fast as possible. Thankfully, you can apply enzymes alongside bat guano as a catalyst to speed up the process. Liquid enzyme formulas will quicken the release and allow your deprived plants quicker access to this vital nutrient.

How to use guano:

1. As an organic soil mix with bone meal and chicken manure

Use guano as part of an organic soil mix from the start. Along with bone meal, chicken manure, feather meal, and rock dust, guano provides a broad spectrum of essential nutrients, vitamins, and minerals for the cannabis plant. Try this recipe for bountiful cannabis growth.

As an organic soil mix with bone meal and chicken manure

2. Watered-in as a tea

Probably the most convenient way of adding guano to your garden. Here’s a recipe:

  • Use 1 tablespoon of guano per litre of water
  • Use warm water, not hot! You will kill the microorganisms
  • Stir the water as you add the guano
  • Leave to rest overnight
  • Use once per week to guarantee lush growth
  • Try to use chlorine-free water for this recipe. You can either use distilled water or simply boil some tap water for 15 minutes and then allow it to cool. You can also make a bat guano tea bag to help the nutrients leach out into the solution. Wrap your bat guano in a ball of cheesecloth and seal with an elastic band. Use a stick to keep it pinned down to the bottom of the container overnight.
Watered-in as a tea

3. Applied directly as a soil amendment

Add guano to the soil for a boost in plant performance. Here’s how:

  • Dig it in (under the mulch) so that it activates properly
  • It will dry, clump, and not work as effectively if only sprinkled on the surface
  • Water-in well
Applied directly as a soil amendment

4. Apply as a compost tea

You can use bat guano to make a more nutritionally charged compost tea. To make this nourishing elixir, you’ll need:

  • Large bucket
  • Air stone
  • 5 litres non-chlorinated water
  • 65g fully finished compost
  • 1 teaspoon blackstrap molasses
  • 5 tablespoons bat guano
Apply as a compost tea

Add all of the ingredients into the bucket and stir thoroughly. Turn on the air stone and let it aerate the solution for 48 hours. During this time, aerobic beneficial microbes will colonise the sugars in the nutrient-rich mixture. Dilute 1 part compost tea to 10 parts water and apply it as a foliar spray or soil drench to supercharge the soil food web and enhance flower production.

Why is guano good for cannabis?

The savvy contemporary cannabis consumer is learning to demand high-quality, organic marijuana. Guano is one way of achieving world-class quality when growing organically indoors or outdoors.

The benefits of guano for plant growth are numerous:

  • It improves soil texture. If the soil is too loose, guano will bind it better and increase water retention. If the soil is too dense, guano will loosen the texture and let water penetrate more efficiently.
  • Bioremediation. Guano can help flush toxic elements from the soil while protecting the roots microbially and continuing to feed the affected plant.
  • It encourages healthy decomposition of exhausted material. Adding guano to compost speeds up the composting process and improves friability.
  • It is a slow-release fertiliser. Guano will provide nutrients for most of the life of your plant.
  • It is a pH-adjuster, buffering the pH of the root system.
  • It controls nematodes and is a natural fungicide against chitin (from insect shells).
  • It keeps soil friable and acts as a soil conditioner. Guano adds beneficial enzymes and microflora for continuous soil health.
  • When combined with other additives like worm castings and various meals, guano helps create thriving colonies of root fauna.
  • Used as a dilute spray, guano can help provide plants with fungal protection.
  • Creates a bold and long-lasting terpene profile during the flowering phase.

  • High phosphorus levels induce heavy flowering and thicker branches that support the weight of heavy buds.
  • Valuable micronutrients and organic matter benefit cannabis plants and the soil throughout the entire growing cycle.
  • Because different bat guano fertilisers possess varying NPK values, growers can mix different products to create unique macronutrient ratios.

Things To Avoid When Using Bat Guano

While bat guano works wonders to boost soil health and enhance flowering, you need to keep the following points in mind when using bat guano for weed:

  • Bat guano can damage lung health and cause diseases such as histoplasmosis in those with compromised immune systems. Always wear a mask when mixing it into water.
  • Use your bat guano preparations immediately. Leaving them to sit will lead to the growth of bad bacteria.
  • Keep your bat guano powder out of direct sunlight and off cold floors.

Guano has a long history

Guano has a long and interesting history as one of the most prized fertilisers in the world. Since well before the arrival of Europeans, guano was a revered fertiliser by the Incas and older South American cultures. It was so important that Incan rulers divided the guano-bearing islands among the provinces. How much could be mined and when were strictly regulated.

Between 1806 and 1841, guano caused astonishment and trepidation in European and new-American farmers. This horticultural curiosity caused such huge and healthy plant growth that it was feared the soil may be depleted irreparably. Within a few years though, it was in great demand by every farmer in the world.

Two million tonnes were imported by Britain from 1840 onwards, and the government of the United States made it a matter of agricultural necessity. During his tenure, President Fillmore said “Guano has become so desirable an article to agricultural interests in the US that it is the duty of the Government to employ all means properly in its power for the purpose of causing this article to be imported into the country at a reasonable price".

Massive fortunes have been won and lost over the centuries from guano mines. In the mid to late-nineteenth century, it caused a mania not unlike the California gold rush. Over a forty-year period, Peru exported over twenty million tonnes of guano around the world for a profit of two billion dollars.

Rich in essential macro and micronutrients, bat guano is an organic superfood that will delight the contemporary cannabis grower. For naturally flourishing plants, guano is an unbeatable addition to any organic grow, both indoors or outdoors.

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