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Wednesday, August 5, 2015

Make Compost Tea (as easy as 1,2,3!)

2016 Addendum:  As Oprah says, "When you know better, you do better..."  

Since posting this, I have learned that research has shown that compost tea may not be as useful as advertised.  There is some question as to how many and what type of bacteria it adds to the soil, and whether the nutrient content is as effective as just mulching with compost.  There is also a risk with spraying the tea onto leaves that you are going to eat - it may spread bacteria over the plants that could cause disease in humans.

On the other hand, there is some evidence that spraying plants with compost tea may have an effect on whether a plant can stand up to certain diseases.  Compost tea may also help to improve plant growth if the plants are set in very poor soil.

With these pro's & con's in mind, I would suggest the following: 

1. Always work to improve the soil first by adding organic material (compost, manure etc.) directly to the soil first.   This is likely all you need to do.

2. If you choose to use compost tea anyway, please avoid spraying it over plants that you eat.  It would be awful to contract an e. coli infection (or other infection) from eating a plant covered in bacteria from compost tea! Perhaps consider only using it on inedible perennials that could use a health boost... and then only with caution. Wash your hands well after use, and avoid spraying at a time when children and pets may be around the sprayed plants.

For more information about this please see:

 Alberta Urban Garden:
Does Compost Tea Work?
Does Compost Tea Work? - 2 

Linda Chalker-Scott Wisconsin State University:
The Myth of Compost Tea part 1  
The Myth of Compost Tea part 2
The Myth of Compost Tea part 3


Compost tea makes a great nutrient enhancer for your garden.  It is a "liquid feed" that adds nitrogen, micronutrients and beneficial bacteria to the soil.  To apply it, you just water your plants with it.

Making it is also simple.


1 bucket

2 cups of compost and/or manure. (See my previous bog post for sources of free compost.)

1 6"x6" (give or take) piece of permeable cloth (cheese cloth or burlap work well)

1/4 cup molasses (ok to substitute sugar, corn syrup or honey)


Water -- Note: If you have city water, do
 NOT use water straight from the tap because it contains chlorine that may kill off the composting bacteria. Use either rain water, or water that has sat overnight in a bucket so that the chlorine can evaporate.

Fish tank bubbler (optional)


First, collect about 2 cups of compost and place it in a square of cloth.

Next, tie the cloth shut with string to form a giant compost "tea bag" and tie it so it is dangling into a bucket.

Then, add about 1/4 cup of molasses to the bucket and fill it to the top with water. (The molasses provides sugar to feed the bacteria as well as some micronutrients.) 

Let the mixture steep for at least 48 hours.  

OPTIONAL: If you have a fish tank bubbler, you can use it to add oxygen to the mixture. This will help the bacteria proliferate more quickly.

Once the mixture has finished steeping, you can either apply it directly to the garden, or store it in jugs for later use.

Happy gardening!

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