Update: April 2017. Research has convinced me the average home compost tea has almost no benefit with leaf applications for disease control other than sheer luck.
It’s all about how good the tea is made and the average home brewer – contrary to the Internet – simply doesn’t produce good tea on a reliable basis.
Even though I had a highly rated compost tea maker, I stopped making tea. It’s far easier to spread compost thinly to achieve the same practical advice. And to maintain a constant mulch that provides food and shelter for soil microorganisms.
Addendum to the update: November 2018
I have seen no research or data on the home scale that has convinced me to change my mind about how I now use my compost.
Apply the compost directly to the garden. Don’t bother with compost tea. The odds of being able to produce consistent and effective tea on the home scale are too low.
Having said that, I’ve left the article here for those who would like to experiment with it in their own garden.
Some compost tea folks think the quickest way to improve your soil is to use compost tea on a regular basis.
Many of those in the bioremedial (repairing soils) business will apply it several times a season (think monthly) to soils that require assistance.
But also understand that without testing each batch of tea – you really don’t know what you’re applying.
This makes sense on the home scale of compost tea making for several reasons.
The first and most obvious is that it is a safe and effective way to work in your garden – safe for your family and your pets.
And if we mess up with our tea making, it is far easier to correct the problem next month than assume everything is fine. We often don’t know that we’ve let the air bubble too long or that the particular bacteria that’s living right now doesn’t like being applied through a sprayer – – or any number of things that those living organisms might not be able to tell us.
Repetition means we’ll do some good – if only by dumb luck. 🙂
And often we don’t have enough compost to spread it an inch deep across our properties.
Brewing the tea – increasing the numbers of beneficial microorganisms – is one way to maximize those we do have.
And finally, on the home scale making compost tea can be as simple or as complicated as you want to make it.
Aquarium air pumps work fine for most of us and a 5-gallon plastic bucket will brew a fine batch of tea.
Your compost tea should show big bubbles should be roiling water
Our objective is to make aerobic tea (one made with oxygen) rather than anaerobic tea (one made without oxygen)
Those made without oxygen are pretty much just stagnant water without any good microorganisms left alive (the good guys need oxygen to live).
- This means we take a 5-gallon plastic pail – put an aquarium pump beside it and run the plastic hose into the bottom of the pail.
- We weight the hose down with a big nut so it doesn’t rise to the top of the pail.
- We do not use an aquarium stone to break up the air into tiny bubbles. We want big, powerful bubbles so do not use a stone. Besides, those darn things plug up pretty quickly with algae and other bacteria that attack them.
Making Compost Tea
Add water to the pail. If you’re using municipal chlorinated water, you have to eliminate the chlorine. (chlorine kills microorganisms) You can do this by letting the water sit for 24 hours or you can visit an aquarium pet store and get some water treatment tabs that do the same thing.
In either case, leave the bubbler going to help outgas the chlorine.
Put a small shovel of compost into a bag. The bag should be big enough to let water go through it but small enough to hold in the compost particles.
Put the bag into the water (with the air stone running).
It helps if you add “food” to feed the bacteria and fungi. With no food in the water, they’ll quickly die. Hey, so would you without food.
See below for recipe and suggestions
Let the mix bubble for 12-24 hours and then apply immediately Do not let it sit around or the microorganisms die off and you wind up with anaerobic compost tea (we don’t want that).
Make the tea outside so that the microorganisms produced are the same ones needed in the garden.
Cool weather will require organisms that thrive in cool weather and you can repeat the tea making when the weather warms up to produce organisms for warmer weather. Spreading the Compost Tea
Spreading the compost tea is also very easy in the home garden. You can use either a watering can or a regular backpack sprayer.
Do NOT use a sprayer that has been used for chemical sprays. It will kill the bacteria and fungi.
Even if you rinse it out, there is generally a residue left that makes it useless for organic spraying.
Spray or pour compost tea everywhere.
You should get it on plant leaves, on lawns, on vegetable gardens; wherever it lands, the organisms that will survive in those conditions will find food and will begin to do their job (eating the bad guys).
In my small garden, I use a watering can. When I put it on the lawn, I use a hand or backpack sprayer without the fine nozzle.
A simple compost tea recipe
In a 5-gallon pail, add:
- One small shovel of compost (about 3 big handfulls)
- 2 tablespoons of molasses because molasses contains several different kinds of sugars,
- 2 tablespoons of seaweed emulsion or fish emulsion for the micronutrients (they’ll each give slightly different results)
- 1 teaspoon of citric acid for the bacteria (you can toss in a couple of 500 mg. Vitamin C tablets instead or several tablespoons of lemon juice)
Turn on air bubbler. Wait 12-24 hours and apply.
Like a lot of things, some folks think compost tea is a “magic bullet” that feeds plants, kills plant problems and makes them sexier and better looking.
The reality is a lot more complicated than that.
*If* you have the right mix of micro-organisms in your compost, and *if* you make the compost tea correctly, and *if* you apply it properly then you *might* see some benefit. Or not.
Those that recommend this as a disease preventative or killer have to understand there’s a specific organism causing the plant problem and it will take a specific organism in the compost tea to attack it. If that specific organism isn’t in the compost tea – the tea will have no impact on the existing disease.
There are a ton of variables here that actually work against the average home gardener who makes but doesn’t test his tea (the big guys test every batch)
My take on the home scale production of compost tea is simple.
Compost is better
Apply that all over your garden.
Don’t expect anything but be prepared to be pleased.
Responses to Questions and Concerns Leachate
The liquid coming from the bottom of the compost bin is considered “compost leachate”.
The problem with leachate is that it is anaerobic and while it has nutrient value (the extra water dissolves some of the nutrients and carries them out of the compost) it also “may” contain pathogens from the composting without oxygen (water soaked=no oxygen)
So it’s generally not something we put on the garden. Some folks do – some don’t.
The “official” position of organic aerobic tea specialists is not to use it but it’s your garden. Compost Tea and E. coli bacteria
Does compost tea have e.coli bacteria in it. If you start with manure, yes it *may* contain e.coli.
If you start with compost that doesn’t contain manure (and thus no e.coli bacteria) then you don’t get e.coli in your compost tea. So always make compost tea from good compost and not composted manure.
If you have composted manure, simply apply it to the garden directly where it will do the most good.