A compost tea recipe doesn’t have to be complicated in order to be effective.
In fact, the simplest compost tea recipes are often the best because they’re easier to experiment with.
In case you don’t know, compost tea doesn’t look like the picture here.
It’s actually made by putting a small amount of compost in a bucket of water and bubbling air through the water to detach the beneficial microorganisms from the compost as well as give them air to breathe.
We also add specific foods to feed and multiply those microbes. The resulting tea is applied to the garden.
To make a high-quality compost tea that’s going to provide benefits for your garden, you need to get a lot of factors right — air pressure, water quantity, size of the air bubbles, amount and types of compost and microbes foods, and on and on.
Today, I’m focusing on the ingredients.
Compost Tea Brewing
Whether you buy a compost tea brewer or make your own, you start with just a small amount of exceptionally good, aerobic, nice-smelling, fully finished organic compost.
(Here’s my post on composting at home. if you want to know more about that.)
A mixture of two or three different composts is even better. Using different composts will bring more microbial diversity, and you can even throw in a small amount of healthy soil.
You can put this compost first into a mesh bag or directly into a bucket of clean, room temperature water. Many people use a five-gallon bucket, which is fine if your pump is powerful enough.
If you’re just using a basic aquarium pump, I suggest putting only a gallon of water in the bucket and cutting the ingredients by 80%. Using less water ensures you have enough air moving through.
By “clean” water, I mean it can’t have chlorine in it. If you use city water, you need to let that bucket of water sit out for 24 hours for the chlorine to dissipate, or you can turn on your air pump for 20 minutes instead and that also does the trick.
If your city uses chloramine to disinfect the water, you need to add ascorbic acid (vitamin C) or humic acids to neutralize it.
Your air pump will blow air through tubes in the bucket. The air goes through the water and compost, keeping the environment aerobic to favor the aerobic microbes.
In the old method of making compost tea which was just to let it sit and perhaps occasionally stir it with a stick, those microbes would mostly stay attached to the compost and wouldn’t have enough air to multiply.
The new method gives them the right amount of air, plus we add the foods they need to multiply.
Compost Tea Recipe
Examples of good microbe foods include molasses, kelp, fish, humic acids and rock dust. Obviously, these products shouldn’t have preservatives in them, because preservatives are designed to kill microbes.
Here’s an organic compost tea recipe I’ve adapted and evolved for a five-gallon homemade compost tea brewer. This takes 1-3 days to make. We don’t really know when it’s done if we’re not testing it, but 2-3 days is a good time frame to start. The compost tea ingredients are:
- 2 cups good, aerobic, nice-smelling, fully finished organic compost
- 1 Tablespoon unsulfured blackstrap molasses
- 1 Tablespoon organic liquid kelp fertilizer
- 1 teaspoon organic liquid ﬁsh fertilizer
A good batch of compost tea can be a miracle worker when it comes to fulfilling your organic gardening goals. It’s a microbial inoculant to improve your soil food web, broad-spectrum organic fertilizer to foliar feed your plants, and even pest control (although it can’t legally be marketed for controlling pests).
And this simple compost tea recipe is all you need to get started. If you have any questions, feel free to let me know below.
Update: Nearly 2 years after writing this, I decided to start selling the same compost tea brewer that I use myself. You can check it out (and learn more about compost tea) here.