How To Brew Your Own Compost Tea

Compost tea is a nutrient- and bacteria-rich liquid plant booster made from ordinary compost, water and a few other ingredients. Freshly “brewed” tea can be added directly to soil or sprayed onto your plants’ foliage. Among other benefits, it helps plants absorb nutrients from the soil, improves soil structure, promotes root growth and helps to prevent disease. Compost tea is organic and is safe for fruit and vegetable crops. It’s also gentle enough for seedlings. Best of all, it’s easy to make your own compost tea, and it requires just a few inexpensive supplies. Each batch takes one to three days to brew and yields about 2 1/2 gallons of liquid tea, which you apply to your plants immediately. If this sounds great to you, read on to learn how to brew your own at home!!

To get started, you’ll need a 5-gallon bucket, an aquarium aerator (air pump) and some tubing and bubblers. The aerator and bubblers are used to provide two essential ingredients: oxygen and agitation. Together, these elements unlock the beneficial microbes from the compost and give life to the bacteria. Another key ingredient is some type of bacteria food—I use molasses.

Things You’ll Need

  • 2 five gallon buckets
  • aquarium aerator kit with tubing
  • air stones (sold by aerators)
  • mature compost
  • blackstrap molasses
  • something for stirring
  • strainer

Step 1: Set Up the Aerator and Bubblers

Use lengths of flexible plastic tubing to attach two or more air stones (or other type of aquarium bubbler) to the aquarium aerator. Keep in mind that the air pump must plug into an electrical outlet. The air stones much reach into the bottom of a 5-gallon bucket.

Tip: Choose an aerator and bubbler combination that is forceful enough to create a rolling boil when the bucket is full of water and compost. The compost tea brews best with fairly vigorous agitation, as opposed to fine bubbles. A small- to medium-size pump with two or three air stones usually works well. The entire set up, stones and all, can be purchased from a pet store.

Step 2: Dechlorinate the Water

Most city water supplies contain chorine, which is bad for compost tea. If you have city water, you should dechlorinate it first. Here’s how to do that. Fill a 5-gallon bucket with water and let the it sit for 24 hours. The chlorine will evaporate.

Step 3: Brew the Compost Tea

Brewing the tea can take anywhere from 24 to 72 hours, depending on the compost used and the rate of aeration. If the mixture begins to smell bad (not sweet and earthy), it means that anaerobic organisms have taken over, and the batch has gone bad. This can occur when you bubble the tea for too long. Discard a bad mixture (you can pour it on the ground but not near plants) and start over.

  1. Place the air stones in the bottom of a clean, empty 5-gallon bucket.
  2. Fill the bucket about halfway with mature compost.
  3. Add de-chlorinated, room temperature water up to a few inches from the top of the bucket.
  4. Turn on the aerator to begin agitating and aerating the mixture.
  5. Add 2 tablespoons (1 ounce) of blackstrap molasses, then stir the entire mixture with a stick. If the air stones float up during stirring, push them back down to the bottom of the bucket.
  6. Bubble the tea continuously for 24 to 72 hours, stirring the mixture three or four times per day.
  7. Turn off the bubbles and let the compost settle in the bucket for 20 or 30 minutes.
  8. Pour the tea through a strainer to strain out the solids, transferring the liquid to the other bucket.

How to Use Compost Tea

Use all of the compost tea as soon as you finish brewing it. I like to time the brewing to it finishing up in the morning, so it is ready for me when I go out to water. (I always brew for 63-65 hours. This sounds super specific, but it is not. If I start the brew at 4:00pm, which is usually when I am in the garden, it will be ready for me around 7:00-9:00am three days later. I know that I water during that time, so that is ideal for me!) The aerobic bacteria will only live for about four hours after the aeration stops, so timing is important. Once your brew is strained, pour the completed tea into a plastic watering can and go to town. Your veggies, herbs, and flowers will love you for it!!

If you want to keep the garden tips coming, consider growing with me this season inside the Wild Child Kitchen Garden Academy or Wild Child Garden Club. The gardeners who grow with me get the results they want and you will too!! It is the perfect time to get started, so let’s grow!

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