If you're one of those natural tinkerers who like to tweak and tune your setup and conditions until you reach that coveted gram-per-watt result (or more), bat guano for weed cultivation should definitely be on your radar.
Many companies sell bat guano for weed growers, and plenty of happy customers swear by it. In this post, we will investigate what makes bat guano for cannabis a good idea, what the best sources are of this organic fertilizer, and how to use it for optimal results.
What is Bat Guano?
Bat guano is just bat poop that accumulates over time on the floor of the caves where bats live. It's surprising how many metric tons of droppings can be harvested in an old cave, and for many countries, such as Peru, bat guano is an important part of their export trade. Farmers from all over the world buy bat guano as an all-natural organic fertilizer, and cannabis growers in particular value this source of nutrients for both their indoor and outdoor crops.
What is the NPK of Bat Guano?
Bat guano for marijuana is so popular because it contains the three essential chemicals (macronutrients) - nitrogen, phosphorus, and potassium - as well as many micronutrients that contribute to plants' health. The exact composition of a bat guano fertilizer depends on the country of origin and the manufacturer, so NPK can range from 10:3:1 or 10:2:1 to 1:10:0.2 or 0.5-12-0.2. As you can see, different products have one thing in common - they aren't especially rich in potassium (K), while the ratio of nitrogen to phosphorus fluctuates widely.
Benefits of Bat Guano Fertilizer
The main benefit of bat guano for growing weed is that it serves as a source of many important nutrients in their readily available form. Plus, as an all-natural fertilizer, it can become an integral part of organic cultivation and contribute to thriving life in the root zone. Finally, adding some bat guano to the soil improves its texture.
Does the Source of Bat Guano Matter?
As a cannabis grower, you're probably a nature-friendly person and value products that have been obtained ethically, without ruining ecosystems or endangering animal and plant species. Of more practical importance is the exact composition of bat guano for weed growing, as well as its quality as a fertilizer.
Mexican Bat Guano
With its high nitrogen content and middling levels of phosphorus and potassium, Mexican bat guano is perfect for the vegetative phase. The 8-1-1 NPK contributes to the fast growth of foliage and your weed's overall health and vigor.
Jamaican Bat Guano
Jamaican bat guano is totally different in its composition. It's a high-phosphorus variety and thus much more suitable for use during the flowering stage. Bear in mind that flowering cannabis also needs a potassium boost, so you should complement bat guano with some other product(s) rich in potassium (K).
Indonesian Bat Guano
Commercial products using Indonesian bat guano (or based on it) have a ratio of nutrients quite similar to the Jamaican variety - about 0-10-0 NPK. Again, this makes the droppings of Indonesian bats most valuable for flowering plants.
How to Use Bat Guano on Weed Plants
You may want to plan your organic weed grow with bat guano in advance. Alternatively, you may decide to use it in the middle of the run and still get great results. It's all up to you.
Mixing Into Soil
One of the most rewarding ways to grow marijuana is by planting it in supersoil. By supersoil, we mean a medium teeming with organic amendments and soil conditioners that's prepared even before you germinate the seed - and bat guano may be an important part of a successful supersoil grow. Use something like 2.5-5 percent of bat guano, mixing it well with other natural ingredients. The beauty of guano-amended supersoil is that you'll be using plain water from seed to harvest without ever leaving your plant hungry.
Feeding as a Tea
Organic teas are a favorite feeding method for many growers. It can be a sophisticated technique of carefully brewing some solution that is full of beneficial bacteria, but you can instead just let some organic matter sit in water overnight until the nutrients dissolve. This is the way to make organic banana peel tea or bat guano tea for weed plants.
The basic bat guano tea recipe is very simple. Take 2-3 teaspoons per gallon of cold water (1/2 a teaspoon per liter) and let it steep for several hours. The concentration won't be high enough to harm your weed plants, so you can use this nutrient solution instead of plain water.
Alternatively, you may want to make a more concentrated bat guano tea by adding one tablespoon per liter of warm water and letting it brew overnight. A fish tank air pump may speed up the process. This solution will be stronger, and you can use it for a weekly organic boost.
Burying Bat Guano
If you bought a bag of bat guano in the middle of the grow and want to add some to the soil, don't just sprinkle it on the surface. You'll get better results by digging a couple of inches into the medium and burying bat guano under this thick layer of soil. The nutrients will be released whenever you water your pot.
When to Use Bat Guano for Weed
Bat Guano for the Flowering Stage
Be sure to use the correct kind of bat guano for the different stages of the grow cycle. The flowering stage will benefit the most from the Indonesian and Jamaican products, as this kind of bat guano fertilizer for weed is rich in phosphorus (P) and contains only negligible amounts of nitrogen (N).
Bat Guano for the Vegetative Stage
Plants in the vegetative stage will get a major boost from Mexican bat guano, which has a high level of N for explosive growth and enough K to contribute to the correct metabolism and the development of plant tissues. P is present too, but it can safely wait in the root zone until your weed starts to bloom. The important thing is to not wash it away with too much water. Remember: you want almost no runoff when growing organically. Another thing to keep in mind is that strong organics like bat guano are for mature plants and can actually hurt seedlings and young clones.
How Often to Use Bat Guano
If you prefer to add bat guano with water, the frequency depends on the strength of the solution. With 2-3 teaspoons per gallon of cold water steeping for a few hours, it can be used every time your plants are thirsty. When you brew your bat guano tea with one tablespoon per liter and let it steep for a longer period, the tea becomes much stronger, so treat it as a fertilizer and use it only once a week.
Best Bat Guano Fertilizer
Bat guano can be found in many store-bought fertilizers, where it's combined with other ingredients for enhanced performance in weed gardens. Here are some of our favorites.
Mother Earth Nitro Bat 5-3-1
Suitable for use in outdoor and indoor gardens and mediums as diverse as soil, coco coir, and hydroponics, this bat guano fertilizer is very rich in nitrogen while also having a lot of phosphorus and some potassium. It's perfect for fast-growing plants like cannabis and can be used for biweekly top dressings during the vegetative phase.
Down to Earth Organic Bat Guano Fertilizer 7-3-1
Even richer in N, this bat guano product is the ultimate organic veg fertilizer, but it has also enough P and K to build a strong foundation for the flowering stage. Pre-mix it in the pot before planting, use it as side-dressing, or brew some tea with it. The result will be the same: vigorous and healthy plants with great yield potential. You can even use it in foliar sprays, but make sure to stop once the flowering begins.
Pre-Mixed Potting Soil With Bat Guano
As we've said before, one of the most efficient ways to use bat guano is to mix it in the medium from the start, and in the following products, this job has already been done for you.
Happy Frog potting soil by FoxFarm is the perfect organic medium for your marijuana plants, as it is inoculated with beneficial microbes, while bat guano, as well as worm castings and aged forest products, serve as food for busy little critters. Thanks to this rich organic life, all the nutrients in the medium will be made available to your plants in the most easy-to-absorb form.
This is another popular potting soil containing bat guano but also a cornucopia of sea life products, such as fish emulsion and crab meal. With its airy structure, this medium is great for cannabis plants whose roots love oxygen, while a rich mix of organic nutrients provides enough food for a vigorous start of life. Later in the cycle, you may start to add fertilizers, but not in early veg.