Compost Tea Recipe: A Complete Guide to Brewing Nutrient-Rich Garden Elixir

Compost tea is a liquid fertilizer made by extracting nutrients and beneficial microorganisms from compost or organic matter. This natural brew provides plants with soluble nutrients and a complex community of beneficial microorganisms that enhance soil health and plant vigor.[7] Whether you're looking to fertilize citrus indoors, remove powdery mildew from foliage, or grow basil indoors more successfully, compost tea offers a versatile solution for home gardeners seeking to improve plant performance naturally.

What Is Compost Tea?

Compost tea is essentially a concentrated liquid version of solid compost material.[7] By steeping finished compost in water, you create a nutrient-dense solution that can be applied both to soil and plant foliage. The tea works to suppress foliar diseases and feed your plants simultaneously, making it particularly valuable for addressing common indoor gardening challenges.[3]

Key Benefits of Compost Tea

• Improves soil structure and nutrient availability[1]
• Enhances plant resilience against diseases and pests[1]
• Boosts microbial diversity in the soil, promoting overall ecosystem health[1]
• Increases the population of mycorrhizal fungi and predatory nematodes, which help defend plants against harmful microorganisms[4]
• Helps plants grow faster and increase yields[4]

Essential Materials and Supplies

Before you begin brewing, gather the following items:

• 5-gallon bucket or container
• High-quality, fully finished compost (organic and free of contaminants)[1]
• Non-chlorinated water (rainwater, spring water, well water, or tap water left to sit for 24+ hours)[1]
• Mesh straining bag (optional but recommended)
• Aeration equipment: aquarium pump and air stone (for aerated compost tea)

Optional additives to enhance microbial activity:

• Unsulfured blackstrap molasses (1 tablespoon per 5 gallons)[1][4]
• Liquid kelp fertilizer or kelp meal (1 tablespoon per 5 gallons)[4]
• Fish fertilizer (1 teaspoon per 5 gallons)[4]

Simple Compost Tea Recipe

This easy DIY recipe requires minimal equipment and produces excellent results for most home gardeners:

Ingredients

• Non-chlorinated water (enough to fill a 5-gallon bucket)
• 1 to 2 cups of fully finished organic compost
• 1 tablespoon unsulfured blackstrap molasses
• 1 tablespoon liquid kelp fertilizer (or soak kelp meal in water)
• 1 teaspoon liquid fish fertilizer

Instructions

1. Prepare Your Water: Fill your bucket with non-chlorinated water. If using tap water, let it sit for at least 24 hours to allow chlorine to dissipate, as chlorine can harm beneficial microbes.[1]
2. Add Compost: Place 1 to 2 cups of high-quality, mature compost into a mesh straining bag and submerge it in the water, or add the compost directly to the bucket.[1]
3. Add Optional Boosters: Stir in the molasses, kelp fertilizer, and fish fertilizer to enhance microbial activity and nutrient content.[4]
4. Brew the Tea: Stir vigorously for about 2 minutes to begin extracting microorganisms.[7] If using an air pump, attach it now and let it run continuously for 24 to 48 hours. If brewing without aeration, stir the mixture once or twice daily for about one week.[2]
5. Strain and Use: When ready, strain the compost from the water. Apply the tea within 24 to 48 hours for maximum benefit, as the beneficial microorganisms are most active when fresh.[6]

Application Methods

Compost tea can be applied in two ways for maximum effectiveness:

• Soil Application: Water around the base of each plant to allow nutrients to be absorbed by the roots and coat them with beneficial bacteria and enzymes.[3] This method is ideal for fertilizing citrus indoors and other potted plants.
• Foliar Application: Pour some tea into a spray bottle and spray plant foliage to help suppress foliar diseases such as powdery mildew.[3] This approach is particularly useful when growing basil indoors or managing other susceptible plants.

For best results, apply compost tea early in the morning or late in the afternoon to prevent leaf burn.[1] Use compost tea weekly or bi-weekly to truly allow your plants to benefit from its nutrients and microorganisms.[3]

Tips for Success

• Use only high-quality, mature compost to ensure a nutrient-rich tea.[1]
• Avoid over-brewing; compost tea should smell pleasant and earthy. If it develops a foul odor, discard it and start again.[1]
• If using manure-based compost, ensure it is fully decomposed to avoid harmful pathogens.[5]
• Keep the brewing environment at above-freezing temperatures, ideally out of direct sunlight.[5]
• Store finished compost tea in a cool location and use within 24 to 48 hours for optimal microbial viability.[6]

Alternative Recipe Using Plant Material

If you prefer not to use traditional compost, you can create a nutrient-rich tea using stinging nettles and comfrey, two powerhouse plants that are easy to grow and rich in bioactive compounds:[5]

• ½ to 1 gallon loosely packed comfrey leaves, coarsely chopped
• ½ to 1 gallon loosely packed stinging nettle leaves (use gloves when handling)
• Approximately 4 gallons of non-chlorinated water to cover plant material

Place the plant material in a bucket, cover with water, stir, and let ferment in an out-of-the-way place for 3 to 10 days, stirring occasionally.[5]

More tips in the section Garden & Houseplants Care