By Adam Parsons Reviewed by: Gloria Payá

Organic cannabis cultivation foregoes salt-based chemical fertilisers in favour of nurturing the soil's “micro-herd”. That doesn't mean force-feeding a bunch of mini-cows. The micro-herd is a complex community of beneficial microorganisms including bacteria, fungi, algae, yeasts, and other organisms.

With this type of gardening, you feed the herd, and as the microorganisms digest their food, the byproducts feed your plants. This natural technique is perfectly balanced and virtually eliminates problems like overfeeding, deficiencies, and nutrient lockout—when done properly. You don't even need to worry about pH levels.

But doesn't that mean you'll sacrifice potency because you have to give up those designer bud enhancers and THC boosters? Not necessarily. Lactic acid bacteria (LAB) may work even better.


Lactic acid bacteria (LABs) constitute a broad heterogeneous group of food-safe microorganisms that are used to make yoghurt, pickles, and other fermented foods. Sometimes, food processors also use LABs as a sanitiser. When added to either a liquid or solid that contains some type of sugar, LABs consume and digest the sugar, then excrete lactic acid as a final metabolite.

Not only do these bacteria cause no harm, but they're as good for you as they are for your cannabis plants. You have lactic acid bacteria in your own personal microbiome that lives in your digestive tract, and many doctors recommend adding a probiotic supplement containing LABs if you have ongoing stomach problems. For example, eating yoghurt (probiotic food) on a regular basis helps too.

Lactic Acid Bacteria


In theory, the addition of lactic acid bacteria to your organic grow will increase both the trichome and terpene production. This theory is backed up by real scientific research that you can read for yourself in The Plant Journal[1] and Frontiers in Plant Science[2].

Here's the simple version. As they digest sugars, your LABs create a short-chain fatty acid called hexanoate as a byproduct. Cannabis plants synthesise hexanoate to produce terpenes and cannabinoids. By adding more hexanoate, you provide the building blocks for more terpenes and, theoretically, more THC.

Another study discusses how farmers of all types can use LABs to boost plant growth[3] by making organic fertilisers more bioavailable, and prevent disease by suppressing multiple types of bad fungi and bacteria. This means bigger, healthier cannabis plants that yield more.


If you're growing organically and use the no-till method, your soil probably already contains LABs. Lactic acid bacteria are everywhere, even in the air, so they'll be introduced to your soil as leaves and other matter reach the surface and start to decay. LABs that are already present in your soil are feeding on old organic matter too.

Most of the LABs in your soil can be found within 15cm of the surface, as they grow more in oxygen-rich regions. Microorganisms that fall into this category are called soil-borne facultative anaerobes. That means you should be able to enrich your soil from the surface with additional lactic acid bacteria if you so choose—but not everyone agrees this is possible.

If you want to give it a try, you can add lactic acid bacteria serum (LABS) to water and spray it on the soil or directly on the plants.


When trying to promote a healthy micro-herd, avoid applying salt-based chemical fertilisers to your soil. They will kill most of your beneficial microbes while allowing some of the harmful ones to survive.

Avoid disturbing the soil as much as possible. The largest amount of LAB will be just beneath the surface, and exposing them to UV light can kill them. That's also why you should only apply lactic acid bacteria at night or right before you turn your lights off.

How to add Lactic Acid Bacteria


You can culture your own lactic acid bacteria serum using mostly items you probably already have at home. Here's how you do it:


  • 340g rice
  • 240ml water
  • 1 litre organic milk (commercial milk may contain antibiotics)


  • Wide-mouth glass jars
  • Cheesecloth(s)
  • Rubber band
  • Paper bag
  • Clear pitcher


1. If your water is chlorinated, let it sit out for 24 hours so the chlorine can dissipate.

2. Put equal amounts water and rice in a jar.

3. Shake well, then strain through cheesecloth into the second jar. The water should be milky-looking.

4. Cover the jar with a fresh piece of cheesecloth and secure with a rubber band.

5. Place the jar in a paper bag or wrap it with a cloth to seal out the light.

6. Let the jar sit in a warm, dark place.

7. Check daily for residue to settle at the bottom, and for the mixture to have the sour smell that tells you fermentation has started. It will take 2–3 days if the temperature stays in the 25–30°C range. Otherwise, this step could take a week or longer.

8. Pour the milk into a clear pitcher.

9. Pour the fermenting rice water into the pitcher, straining through a clean piece of cheesecloth.

10. Cover the pitcher with more cheesecloth and secure with a rubber band or the pitcher top. Make sure it's secure, but there's still airflow.

Lactic Acid Bacteria Handmade

11. Put the pitcher in a paper bag or wrap it with cloth to seal out the light.

12. Place it in a cool, dark place.

13. Check once a day until you see three distinct layers form. This can take up to a week.

14. Scoop out the top layer (the curd) and discard.

15. The serum (the whey) will be the middle layer that has a clear, yellow colour. Slowly pour off the serum into a clean jar, straining through cheesecloth again. Be careful not to mix in any of the bottom (sediment) layer.

16. Seal the jar loosely so gas produced by the ongoing fermentation can escape.

17. Refrigerate.

The serum is alive. It'll continue to produce small bubbles and should have a mild sweet/sour aroma. If it smells like it's rotting, the serum is contaminated with other bacteria and should be discarded.

To use, dilute the serum by adding 30ml to 1 litre of dechlorinated water, and add to spray bottles. One batch of serum can make up to 500 litres of spray.

If you can't refrigerate your serum, you can stabilise it by adding an equal part of molasses or brown sugar to the mix. This gives your LAB culture something to feed on while waiting to be used on your cannabis plants.

External Resources:
  1. The hexanoyl-CoA precursor for cannabinoid biosynthesis is formed by an acyl-activating enzyme in Cannabis sativa trichomes
  2. Priming of Plant Resistance by Natural Compounds. Hexanoic Acid as a Model - PubMed
  3. From yogurt to yield: Potential applications of lactic acid bacteria in plant production
This content is for educational purposes only. The information provided is derived from research gathered from external sources.

Are you aged 18 or over?

The content on is only suitable for adults and is reserved for those of legal age.

Ensure you are aware of the laws of your country.

By clicking ENTER, you confirm
you are
18 years or older