Introduction
Compost tea is a liquid fertilizer made by steeping finished compost in water. It extracts beneficial microbes and water-soluble nutrients, delivering them directly to plant leaves and roots. Gardeners use compost tea to boost plant health, improve soil biology, and suppress certain foliar diseases.
Brewing compost tea at home is simple and inexpensive. You can make a basic bucket batch in minutes, or brew aerated tea for a more microbially active mixture. This guide explains both methods and how to apply them safely.
What Is Compost Tea?
Compost tea is exactly what it sounds like: compost soaked in water to create a nutrient-rich liquid. The finished tea contains soluble nutrients, humic acids, and beneficial bacteria and fungi. When sprayed on leaves, it may help protect plants from disease by occupying surface space that pathogens would otherwise colonize.
There are two main types. Aerated compost tea is actively bubbled with an aquarium pump to encourage aerobic microbes. Non-aerated compost tea is simply compost soaked in water for several days. Aerated tea is more biologically active but also more perishable.
Aerated Compost Tea Recipe
For actively aerated compost tea, you need a five-gallon bucket, finished compost, water, an aquarium pump with air stones, and a mesh bag or old pillowcase to hold the compost. Fill the bucket with water and let it sit for twenty-four hours to dissipate chlorine, or use rainwater.
Place two to three cups of finished compost in the mesh bag and suspend it in the bucket. Turn on the pump and bubble the mixture for twenty-four to thirty-six hours. Keep the bucket out of direct sunlight. Use the tea immediately after brewing for best results.
Simple Bucket Compost Tea
If you do not have an air pump, make a simple bucket tea. Fill a bucket one-third full with finished compost, then add water to the top. Stir daily for five to seven days. Strain through mesh or burlap and dilute until the liquid looks like weak tea. This version is best used as a soil drench.
How to Apply Compost Tea
Apply compost tea as a foliar spray or soil drench. For foliar application, strain the tea well to prevent sprayer clogging and spray leaves in early morning or evening. For soil drenches, pour the tea around the base of plants. Apply every two to four weeks during the growing season.
Tips for Best Results
Always start with mature, sweet-smelling compost. Immature compost can contain harmful pathogens or phytotoxic compounds. Use the tea within twenty-four hours of brewing, especially aerated versions. Never store brewed tea in sealed containers, because gases can build up and burst the container.
Emma Richardson
Emma Richardson is a passionate home gardener and sustainability advocate with over a decade of hands-in-the-soil experience. She writes practical guides to help people grow their own food and live more sustainably, no matter their experience level or available space.
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