Why Compost Tea Works

Keen gardeners all know the value of compost. Compost simply is a soil modifier and power food with no equal. But what about compost tea? If you have not used compost tea yet, you are in for a real treat. The good things you’ve heard or read are true… compost tea really is the magic juice you’ve been longing for! Give your plants a few applications and you’ll be a convert for life when you see the results.

How Compost Tea Works

Understanding the actual aim of compost tea brewing will give you the most insight into why compost tea works so well and I think it will make you a better gardener. So let’s dig in…

A microscopic web of life is at work all around us. In our soil, on the leaves of plants, on our skin and even on benchtops we thought were clean! On any organic surface you can think of, you can rest assured there’s a colony of invisible lifeforms, living and dying, eating and being eaten, processing nutrients, converting sugars and contributing to the ecosystem. Amazingly, just one handful of healthy soil is home to a mind-boggling 15,000 species of bacteria, 8,000 species of fungi as well as a variety of protozoa and nematodes, numbering in the billions. Some bacteria are good. Some are bad. Some fungis help and some cause trouble. 

The goal of brewing compost tea is to “farm” and multiply the beneficial bacteria and fungi in order to inoculate the soil or leaves of plants with the desirable species. Making compost and introducing it to our garden is the traditional means of treating soils to cause an increase of desirable organisms in the root zone. Compost tea brewing is an extension of the process, a means of supercharging the population growth and producing a liquid which can be used as a foliar spray to inoculate the leaves as well. Brewing compost tea also enables us to make a small quantity of mature, well finished compost go much further.

Brewing Compost Tea

Compost tea is produced by steeping (soaking) mature, well finished compost in water that is kept aerated. Aeration is vital because the beneficial bacteria we need are aerobic and require oxygen to survive and thrive. Molasses is added to feed the good bacteria in order to accelerate their population growth.
There are many different compost tea recipes and techniques documented and available online but here’s a basic outline…

Items You’ll Need:

A 5 gallon bucket
One aquarium air pump able to run 3 “air stones” or bubblers.
Several feet of plastic air tube, 3 bubblers and a gang valve to distrubute air to the air stones.
A fabric bag for straining the solids out of the tea – an old pillowcase is suggested

The Method:

Arrange the three bubblers, spacing equally, on the bottom of the 5 gallon bucket
Add the mature compost to the bucket to about a third of it’s capacity
Top up with clean potable water free from chlorine to within 2 inches of the top
Start the pump and aeration process
Add 1 oz of unsulfered molasses and stir through the mixture
Stir the mixture gently a few times a day taking care not to move the air stones
After 2 but no more than 3 days strain off the liquid and apply immediately to plants; you can use it as either a foliar spray or a soil drench around plant roots.

Vital Points For Brewing Compost Teas

It’s vital to only use well-finished compost that you can be quite confident has no remaining pathogens. Sugars in the molasses will feed pathogens like E. Coli and cause an explosion in their population, making the tea a danger. Ideally, the compost you use will have reached and maintained a temperature of 150 degrees F for three days during the process of composting in order to eliminate pathogens. High quality compost that you get from automatic kitchen composters like the NatureMill or worm compost bins is best for compost tea brewing.

Making and using compost tea is an effective way to dramatically improve your gardening results. Join the thousands of happy compost tea brewers around the world, get brewing today!