Compost tea

Compost tea

Compost Tea

What is it? And why should I use it?

In todays article I wanted to cover a fairly broad topic. But one that comes with a lot of confusion. We will be talking about compost tea. How to brew it. Do's and don'ts.

There's going to be a lot to unpack here, so I want to start off the conversation with pre-packaged tea's VS home made recipes.


Pre-mixed VS Home Made


There are actually quite a few good pre-mixed tea's out there. For example.


Red Frog Premium Blend Compost Tea

Good all around tea. Well balanced for any part of the growth cycle.


Xtreme Tea Brews

It's mykos, earthworm castings and kelp. Not as many inputs as others, but the price point for a 5 gallon brew is good.


Vital Tea

This is essentially vital earths compost tea blend. Minus the Mykos and Fish Hydrosylate.

In all of these cases, something is better than nothing. However, nothing will ever compare to a home brew. 


Home Made

We're always going to start out with a place for the microbes to live and breed. Typically we'll start off with a blend of worm castings and compost. Below I will give you a list of various inputs. And to the best of my knowledge, what they are supposed to do. The reason I say to the best of my knowledge, is because a lot of this information is difficult to pinpoint and/or prove. so take it with a grain of salt. 


Brewing Inputs

Here I'm going to add a small, but fairly detailed list of potential inputs you can use. While in my opinion, teas are better for brewing life. Some people like to brew for nutrients. The below like will show you generally what things you can add in, and what they'll do. Please bear in mind, that if you're brewing for life, the higher the NPK value is, the less environmentally friendly you're making your brew for life cultivation.

Ingredient NPK What does it do?
Alfalfa Meal 2.5-0.5-2.5 Adds NPK to brews, also a natural source of Triacontanol
Azomite 0-0-0.2 Adds trace minerals to brew. Especially good if starting with RO Water
Bloodmeal 12-0-0 Adds nitrogen, can scare away some small pests. 
Bone Meal 3-15-0 Adds slow release Phosphoros and Calcium
Crab Meal 4-3-0 Adds NPK, Calcium and Chitin
Fish Bone Meal 3-16-0 Adds fast release NPK, Calcium and trace elements
Fish Meal 8-6-0 Adds NPK, and fish oils that can feed beneficial bacteria
Humic Acid 0-0-0 Chelates Minderals, can make nutrients more Bio-Avaialble
Kelp Meal 1-0.1-2 Trace Minerals, Amino Acids, Cytokinins, and simple carbohydrates.
Langbeinite 0-0-22 Adds Sulfur, Potassium and Magnesium
Neem Seed Meal 6-1-2 Slow release Nitrogen, can deter some bugs. 
Oyster Shell 0-0-0 Adds Calcium
Rock Phosphate 0-3-0 Adds Phosphorus
Shrimp Meal 6-6-0 Source of Chitin, NPK and Trace Minerals
Soybean Meal 7-1-2 Adds Nitrogen, and plant based amino acids 
Molasses 0-0-0 Can feed some Beneficial Bacteria
Mykos 0-0-0 Is a mycorrhizae based innoculant
Great White 0-0-0 Is a mycorrhizae & Beneficial bacterially based innoculant. 
Fish Hydrosylate 2-4-0 Feeds mycorrhizae, and beneficial Bacteria
Compost n/a A living and breeding space for beneficial bacteria
Earth Worm Castings 1-0-0 A living and breeding space for beneficial bacteria

Have some other inputs you'd like added? Leave a comment below.

What's your recipe?

Knowing the things you can throw in is all well and good, but sometimes it's nice just to have a recipe. So below is going to be mine. Now with this in mind, I don't typically have a lot of brand loyalty to individual inputs. However, I will also explain why I use what I use. Also, keep in mind a lot of this I put in by look, feel and handfulls. So i'll try to get the measurments as accurate as possible, but I may be a little off.

50 Gallon Brew Recipe

Product How much? Why do I use it?
Malibu Compost 4 Liters Well.. it's compost tea. I like it for nutrients, and biology. I use malibu specifically because I usually have a pallet of it on site.
Humisoil 2 Liters I use ancient Forest humisoil for thehumates, a good spot for microbes to live and the microbes that come along for the ride. Again, not a lot of loyalty here pick whatever version you can find.
Wonder worm Castings 2 Liters I actually use Wonder worm specifically, because so far I've found it to break down the best into the water. The more it breaks down, the more biology I get. Plus more of those lovely humates.
Kelp meal 500ML I use kelp for a ton of benefits. Good nutrition, good food source for other microbes. If i'm in flower, I may switch to a higher potassium version, like Kelplex (0.5-0-17)
Insect Frass 200 ML Good home for microbes, also has been speculated to help plants build defenses.
Alfalfa Meal 200 ML Good home, good nutrients. Any brand will do on this one.
Azomite 100 ML Since i'm using RO Water in my Brew, I want to replenish the lost minerals. I'm just as happy to use glacial rock dust.
Fish Hydrolysate 500 ML Bacteria has enough to eat, this is to help the fungus. I actually use this one specifically because under a scope it seemed to have the best fungal numbers. If there's something better out there, I don't know about it.
Mykos 200 ML Seems to me, to be the cheapest source of Glomus Mychorizae out there. The live ones are good for the roots, the dead ones are good food for the bacteria.
Dirt MD 250 ML I like to add a humic because it makes all nutrients play together better. So why not? Also I've seen a few studies on it mitigating the effect of chlorine to some degree, which is helpful if we have to use a chlorinated water source after we're done brewing.

By the time my brewing is done (In usually about 4 hours, or until it smells less like a fish market, and more like walking by a river.) my finall PPMs of my solution are usually about 500PPM.

How much should I Dilute it?

This will depend on the PPM of your solution. In the case of my recipe, I would say yes. At least 1 part tea, to 5 parts water. At most 1 part tea, to 30 parts water. But my tea is for biology, you may be brewing a nutritional tea. In that case, you may want to let your PPM meter be your guide. Generally speaking, seedlings and clones want about 300PPM, vegetative plants about 600, and flowering about 1200. You're mileage may vary, but it's a good starting point.

How often should I add it?

That will depend on what your brewing. A biological tea doesn't need to be refreshed very often. In fact, if you keep feeding it, you should really only have to do it once. If your mostly feeding your plant through tea, you would want to use it as often as you would a typical fertilizer. About once a week. For a balanced recipe like we have above, every two weeks is fairly reasonable.

Can I foliar spray it?

Absolutely! There are plenty of benefits for doing so. Depending on what microbes you have in your tea you may get anything from nutrients, to natural defenses for your plant. And even if you have no microbes that combat things like Powdery Mildew. Beneficial Microbes simply living on the leaf leave less food on the plate for more harmful things. If you are going to foliar spray, you may want to consider adding a wetting agent. It's certainly not nessesary, but it will spread your solution onto the leaves more evenly.


Here we will be discussing brewing methods and the various brewers you can use. As you may imagine there are likely an infinite things we could build, and methods we can use. But this should be a good jumping off point.



What you will need:

5 Gallon Bucket

Air Pump (You can use a single outlet pump, but the bigger the better.

Air Stone (Optionally, you can use the Bubble Snake)

Brew Bag



Fill the bucket up to 3 or 4 gallons with dechlorinated water. Add the liquid Ingredients of your recipe into the bucket. Put the dry ingredients into the bag. attach the air stone to the pump, and put it on the bottom of the bucket. Put the bag in the water. Try to position the bag so that it's only roughly half submersed in the water. Bubble the mixture from 4-24 hours depending on temperature and recipe. 


Conical Brewer

What you will need:

60 Gallon Conical brewer

Commercial Air Pump

3/8 Tubing

1/2 Grommet

2" PVC Straight

2" PVC Elbow

2" Shut Off

55 Gallon Brew Bag


PVC Cement



The bottom of the tank will have a 2" Output. So grab your 2" fittings, and either thread them into place, or if they don't have threads glue them into place. The order should be Elbow>Straight>Shut Off.

Now in the 2" straight, drill a hole big enough for the 1/2 grommet to fit very snug. If you did it right, the tubing should barely be able to fit into the grommet. Once you are satisfied with the seal. Use your silicon on the bottom of the grommet to ensure there are no leaks. In my experience, the tightness of the seel is good enough to not have to silicon the tubing, but if you want to. Feel free.

Once everything is dry, hook up the other end of the tubing to the commercial air pump. Fill the brewer with dechlorinated water. Clip together your brew bag and slide it through the hole at the top of your brewer lid. In my case, I also slide a bamboo stake between the hole and the clip to ensure the whole thing doesn't fall in.

Try to position the bag so that it's only roughly half submersed in the water. Bubble the mixture from 4-24 hours depending on temperature and recipe.


How Long Should I brew?

I know I gave you a time limit before, but that's not always necessarily true. It actually depends a bit on what you want your brew to be. If your going for Fungus/Bacteria that will depend on how dominant you want each to be. Generally bacteria grows faster, and will out grow fungus if given time to do so. For fungal Dominant teas, I generally recommend a shorter brew.

For Bacterially dominant longer brews start to make sense. But we also have to take temperature into account. in a typical 70-75 degree environment, a bacterial brew can take 24-48 hours. In hotter temperatures like 85, you'll only want to give it half that time, due to the potential anaerobic conditions. The hotter water gets, the less it's able to hold onto oxygen. And if the oxygen gets too low you, may accidentally invite some bacteria that you didn't really want in your brew.

If you're essentially just trying to brew your own nutrients, the more time you spend the better. Generally a 2 day brew is reasonable. What you're really looking for though, is for all the soluble compounds to get solved so that you're only left with the remaining carbon.

With all that said, how long do I brew? Only a few hours. I brew for what's considered an "extract". I'll basically brew until the fish smell is gone, and I know everything has woken up. And then I pour. Why do I do it this way? Well because most of the stuff i'm trying to grow in my brewer also grows just fine in soil. So once they're awake, why not just send them to the soil and let them fight it out there? Unless i'm going for something specific, I extract only for higher levels of bio-diversity. 

If you have any questions, or opinions feel free to leave a comment below!


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