How To Brew & Apply Compost Tea

compost-teaCompost tea is a liquid extract of compost that contains plant growth compounds and beneficial microorganisms. Liquid extracts have been used for hundreds of years in agriculture to promote plant and soil health. These extracts have historically been derived from a wide range of plant materials and animal manures, using a variety of processing methods.

Compost tea is a good overall plant health booster. Remember—healthy plants are better able to resist pests and diseases! Compost tea is typically used:

• Provide nutrients for foliar or soil application

• As a microbial inoculant via soil application to help build soil microbial populations

Brewing Compost Tea

You’ll need a compost tea brewer to brew compost tea. You can either buy a pre-made one or build one yourself (for under $30).

Here’s a list of what you”ll need:

  • One 5 gallon bucket
  • Dual air pump (an aquarium air pump will work fine for this)
  • Two 5 inch air stones
  • Two 1 inch air stones
  • Two T Connector Valves
  • 25 ft aquarium air hose
  • Nylon paint strainer bag or a burlap bag

Connect materials to the air pump (video tutorial) and put them into the bucket. Fill the 5 gallon bucket with de-chlorinated water. Leave about 3-4 inches at the the top of the bucket.

Next -fill the paint strainer bag about 1/3 full of compost, tie bag with a string and if you are using multiple lines & air stones, you may choose to put one down in the bag.  Now add your bag of compost to the bucket of water and start the air pump.

The bacteria and fungi will need something to eat while they grow and multiply, you can add 1T molasses and 1 T fish emulsion, and about 1/3 cup oatmeal to the water.

Now let it brew for 24 hours.

Using Compost Tea

It is best to plan ahead for maximum benefit from compost tea. Aerated compost tea should be used quickly, since it contains living organisms. Ideally, the tea will be used within 4-6 hours of decanting from the brewer. Keeping it cool, out of the sunlight and in an open-top container, can prolong the useful life of the tea. Periodic stirring or continued aeration will prolong its life even longer. Eventually, however, the organisms in the compost tea will consume all of the food and air available to them, causing their populations to rapidly decline. Any tea that is left over or “expired” can be added to the compost pile or to the soil. Compost tea can be applied to the soil or directly to the plant as a foliar spray. When it is used as a foliar application, it is best to strive for thorough leaf coverage using a fine mist. Foliar applications are best done early morning or pre-dusk to minimize the effects of UV rays. When used as a soil drench, compost tea should be applied so that it moves into the root zone. This can be accomplished by following the tea application with additional water. Use full strength or dilute1:1 (tea to water) for indoor houseplant and garden plants. Drenching a medium size plant requires about 2 cups of tea plus enough water to get the solution down to the roots. Compost tea can be diluted (up to 1:3 tea to water) to cover a larger area like a lawn. When applying to lawns, apply the tea either just before or just after watering. Apply once or twice a month throughout the growing season.


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