The Ultimate Guide to Compost Tea

The Ultimate Guide to Compost Tea

Compost teas are incredibly effective at delivering a dense population of beneficial microbes, soluble nutrients, and bioactive compounds directly to plants. When brewed correctly, they boost nutrient uptake, strengthen plant immunity, and improve harvest quality.

This guide explores how to make compost tea at home and apply either directly to soil or through foliar spraying. When making teas, our objective is to nourish the soil microbiome, support the biology of the garden or orchard rhizosphere, and provide systemic support to balance mineral deficiencies and optimize nutrient uptake in our plants.

This recipe is suitable for all crops, including fruit and nut trees, berries, vegetables, vines, ornamentals, lawns, and field crops. 

Required Equipment

  • 5-Gallon Bucket
  • Air Pump and Air Stone (rated for 5+ gallons) or Hand Drill with Paint Mixer Attachment
  • Fine-Mesh Cloth Brew Bag
  • Strainer (if using Method 2)
  • Spray Bottle or Pump Sprayer (for foliar application)

 Ingredients & Functions

Ingredient

Functional Role

Compost/Worm Castings

Biological Inoculation, Microbes, Mycelium

Chicken Manure

Microbial Stimulation & NPK Boost

White Rice (soaked)

Fungal food, slow-release carbon

Molasses

Primary Energy Source (Sugar)

Sea Kelp

Growth Regulation & Trace Minerals

Irish Moss

Adhesion & Mineral Supplementation

Eggshell Concentrate

Structural Integrity & Calcium

Teregen Ag Micronutrients

Trace minerals, Phytohormones, Amino acids


A Note on Micronutrients

Compost and natural amendments alone often don’t supply enough concentrated micronutrients to correct deficiencies or optimize plant performance. If your goal is to address trace mineral needs and maximize fruit quality, it is often essential to add a targeted micronutrient fertilizer.

This recipe is designed to work best with Teregen Ag micronutrient fertilizers — Grow Champion, Bloom Champion, and Turbo Hume — which provide a complete, bioavailable spectrum of trace minerals, phytohormones, and amino acids.

The Concentrated Base Recipe (per 5-Gallon Batch)

This is a super-concentrate designed to be brewed strong and then diluted for application. One batch covers more ground with less work.

  • 4 Gallons Dechlorinated Water (let tap water sit uncovered for 24 hours or use a dechlorinator) 
  • 4 Cups Aged Compost or Worm Castings
  • 2 Tbsp Unsulfured Blackstrap Molasses
  • 2 Tbsp Powdered Sea Kelp
  • 2 Tbsp Powdered Irish Moss
  • 1 Cup Prepared Eggshell Concentrate (see preparation below)
  • 1 Cup Soaked White Rice (see preparation below)
  • 1 Cup Aged Chicken Manure (composted, wear gloves when handling)
  • 3-5 Tsp Teregen Ag Micronutrient Fertilizer (Grow Champion, Bloom Champion and/or Turbo Hume)

Preparing the White Rice (Soaking Method)

White rice provides a complex carbohydrate source that feeds fungi and sustains microbial activity long after the simple sugars from molasses are consumed. It also provides physical structure for microbial colonization.
  • Measure 1 cup of raw white rice (do not cook it).
  • Rinse briefly to remove surface dust.
  • Place the rice in a bowl and cover with 2-3 cups of dechlorinated water.
  • Soak for 12-24 hours at room temperature. The grains will soften and swell slightly.
  • Drain and add the soaked rice directly to the brew bag, or pour rice and water into bucket if you don’t plan to strain the tea.
  • Do not discard the soaking water—add it to the tea as well; it contains soluble starches that feed the microbes during the brew.
The rice will continue to break down during the 24-hour brew cycle, providing a steady food source for beneficial fungi and bacteria.

Preparing the Eggshell Concentrate (Vinegar Extraction)

This process converts insoluble calcium carbonate in eggshells into soluble calcium acetate, which is immediately bioavailable to plants and microbes.
  1. Collect and rinse eggshells (removing the inner membrane is optional; it will break down during the brew).
  2. Dry them thoroughly, then crush into small pieces (pea-sized or smaller), or lightly pulverize in blender.
  3. Place the crushed/pulverized shells in a glass jar and cover with white vinegar (distilled or apple cider).
  4. Allow to soak for 24 hours or until the bubbling (effervescence) stops completely. The vinegar dissolves the calcium, releasing carbon dioxide.
  5. Strain out the remaining shell fragments. The liquid is your eggshell concentrate.
  6. Use 1 cup per 5-gallon batch. Store unused concentrate in the refrigerator for up to 2 weeks.

Other Additions

In addition to the base ingredients, several common household foods can be added to your compost tea for targeted nutrient boosts. These are all cost-effective, easy to prepare, and well-tested.

Banana Peels (Potassium, Phosphorus, Silica)

Why: High potassium for fruit development, sugar translocation, and stress tolerance. Also contain phosphorus and trace silica.
Prep: Chop 4-6 peels into 1-inch pieces (or leave whole, but less effective). Steep in 2 cups of dechlorinated water for 24-48 hours. Strain and add the liquid to the brew. 
Add: At the start of the 18-24 hour brew cycle. The steeped liquid goes in directly; the solids can go into the brew bag or compost pile.

Used Coffee Grounds (Nitrogen, Organic Matter, Microbial Food)

Why: Slow-release nitrogen, plus organic matter that feeds soil structure and microbial activity. The spent grounds are pH-neutral.
Prep: Rinse briefly to remove excess acidity. No steeping required.
Add: 1 cup (rinsed) directly into the brew bag or bucket at the start of the brew cycle.

Cooled Potato Water (Potassium, B Vitamins, Starch for Microbes)

Why: The water left from boiling potatoes is rich in potassium, B vitamins, and soluble starches that feed beneficial fungi and bacteria. It also contains trace amounts of magnesium and phosphorus.
Prep: After boiling potatoes, allow the water to cool completely to room temperature. Do not use salted water.
Add: 1-2 cups of cooled potato water directly to the brew bucket at the start of the brew cycle.

Note: These household additions are supplementary. They do not replace the base recipe’s core ingredients (compost, molasses, kelp, rice, manure) but enhance them with specific, targeted nutrients.

Brewing Methods

Method 1: The “Clean Extract” (Bagged) Process: 

  1. Place the compost, chicken manure, soaked rice, and Turbo Hume micronutrients inside a fine-mesh filtration bag.
  2. Tie it securely.
  3. Place the bag in the aerated bucket and add all other ingredients directly to the water.
  4. Brew tea for 18-24 hours, aerating regularly (see The Golden Rules below for aeration details)
Benefit: The bulk of undissolved organic matter remains contained. This is the preferred method for foliar spraying to minimize nozzle clogging.

Method 2: The “Direct Infusion” (Unbagged) Process: 

  1. Add all ingredients directly into the water.
  2. Brew tea for 18-24 hours, aerating regularly (see The Golden Rules below for aeration details)
Benefit: Maximum extraction of minerals and microbial life. Requires thorough straining through cheesecloth or a fine-mesh paint strainer into a secondary container before use.

 

Filtration Notes

Regardless of which method you use, if you plan to apply the tea through a sprayer, proper filtration is essential to prevent clogging. 
  • A fine-mesh paint strainer (available at hardware stores) works well. 
  • Cheesecloth folded 2-3 layers thick is a common option for smaller batches.
  • Clean nylon stockings or pantyhose also make an effective and reusable filter—stretch one over the opening of your bucket or sprayer reservoir and pour the tea through. 
Choose a method that matches your equipment: finer filters for fine-mist sprayers, slightly coarser for hose-end sprayers.

The Golden Rules

Aeration: The tea needs consistent oxygenation throughout the brew cycle to keep beneficial microbes alive and prevent anaerobic conditions. An air pump with a stone provides steady hands-off aeration for the full 18-24 hours, but regular manual agitation works just as well.

If hand-mixing, use a hand-mixer, stirrer, or a hand drill with a paint mixer attachment and vigorously agitate for 1-2 minutes every 2-3 hours over the 24-hour period. The key is regular aeration, not necessarily continuous. Never let the brew sit undisturbed for more than a few hours.

The Smell Test: Healthy tea must have a pleasant, earthy, forest-floor aroma. If it smells like rotten eggs or sewage, it has gone anaerobic. Discard it immediately.

Cleanliness: After usage, rinse all equipment thoroughly. Sugars and minerals can encourage buildup or corrosion.

Dilution and Application

This is a concentrated brew. The dilution method depends on how you plan to apply the tea. It can be applied undiluted to soil. Do not apply it undiluted to foliage.

For Soil Drenching

  • Use the concentrate undiluted.
  • Apply directly to the soil at the root edge where the rhizosphere is most active,
  • Then water in with 1-2 gallons of plain water per mature tree (or 1-2 quarts per small plant or young tree).
  • The water-in step moves the concentrated biology down into the root zone where it can colonize, and prevents surface runoff.

For Foliar Spraying

  • Dilute the concentrate 1 part tea to 4 parts water (1:4). This makes it gentle enough for leaves and prevents nozzle clogging.
  • Fill your sprayer and apply to the leaves, ensuring coverage of the undersides where stomata are most active.
  • Stomata open wider on the lower leaf surface, especially in the early morning and late evening.

Best Time to Apply: Early morning (dawn to 9 a.m.) or late evening (dusk) when temperatures are cool, humidity is higher, and stomata are fully open. Avoid midday heat and direct sun to prevent leaf burn and rapid evaporation.

Note for Fruit & Nut Growers

If you are growing fruit or nut trees, this concentrated approach is designed for you. Make one batch and you can treat a significant portion of your orchard.

A single 5-gallon concentrated brew (yielding approximately 4–4.5 gallons of liquid) will cover 8–18 mature trees as a soil drench (at 1–2 quarts per tree, watered in) or 20–45 mature trees as a foliar spray (at the diluted 1:4 ratio). You can brew 2–4 times per year and cover your entire orchard for the season.

Application Rates by Plant Type

The following chart shows how much tea to apply per plant per application — use it diluted 1:4 for foliar spraying or undiluted for soil drenching.

Plant Type

Foliar Application
(diluted 1:4)

Soil Drench Application (undiluted)

Frequency

Vegetables (leafy and fruiting)

1/2 to 1 cup per plant

1-2 quarts per plant

2-4 times per month during active growth, 1-2 times per month pre-harvest

Tomatoes, Peppers, Eggplant

1/2 to 1 cup per plant

1-2 quarts per plant

2-4 times per month through fruit set, 1-2 times per month pre-harvest

Berries (bush and cane)

1-2 cups per plant

1 gallon per mature bush

2-4 times per month during active growth, 1-2 times per month pre-harvest

Vines (grapes, kiwi, etc.)

1-2 cups per vine

2-3 gallons per mature vine

2-4 times per month from bloom to veraison, 1-2 times per month pre-harvest

Fruit Trees (young, under 3 years)

1-2 cups per tree

1-2 quarts per tree (undiluted, watered in)

2-4 times per month during active growth, 1-2 times per month pre-harvest

Fruit Trees (mature)

1/2 to 1 gallon per tree (diluted 1:4)

1-2 quarts per tree (undiluted, watered in)

2-4 times per month from bud break to 4 weeks pre-harvest, 1-2 times per month pre-harvest

Ornamentals and Lawns

1 gallon per 200 square feet

2-3 gallons per 100 square feet

2-4 times per month during active growth, 1-2 times per month pre-harvest

Field Crops (row)

5-10 gallons per acre

20-30 gallons per acre

2-4 times per month during active growth, 1-2 times per month pre-harvest. Stop manure 90 days before harvest

Storage and Use Window

Use the finished tea within 2-4 hours of completing the brew for peak microbial activity. Do not store aerated tea; microbial populations decline rapidly once aeration stops.

Seasonal Adjustments

  • Mid-Growth: Use the full concentrated recipe, including the chicken manure and soaked rice, to support vegetative vigor, leaf density, fungal biomass, and fruit expansion. Apply as a soil drench only. Stop applying all chicken manure at least 90 days before harvest.
  • Pre-Harvest (Last 60-90 Days): Omit the chicken manure entirely. Stop applying manure, focus on micronutrients. Prioritize kelp and rice water for continued fungal support. Your objective shifts to fruit quality, sugar translocation (Brix), and shelf life over vegetative growth.

Closing Thoughts

By brewing and applying compost teas throughout the year, we actively cultivate a resilient soil microbiome and enhance the overall vitality of our gardens and orchards.

This practice moves us beyond basic maintenance, directly supporting our plants to thrive and consistently produce larger, more delicious, and nutrient-dense harvests. It is an effective way to strengthen our plants' internal defenses against environmental stress while building a lasting, productive, and self-sustaining ecosystem.

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