Compost Tea Brewing Calculator

Compost Tea is a liquid extract brewed from finished compost, used as a natural fertilizer and soil amendment. Proper ratios and brewing times are essential for a quality product.

Standard compost tea ratio: 1 part compost : 5 parts water (by volume)

This means for every gallon (or liter) of compost, you add 5 gallons (or liters) of water.

Brewing process:

1. Place compost in a mesh bag or burlap sack
2. Submerge in a bucket of non-chlorinated water
3. Add an air pump (aquarium pump) for aerated compost tea (ACT)
4. Brew for 24-36 hours with aeration
5. Strain and apply within 4-6 hours for maximum benefit

Coverage rates:

• Soil drench: 1 gallon (3.8 liters) of tea covers approximately 50-100 square feet (4.6-9.3 m²)
• Foliar spray: Dilute tea 1:1 with water, 1 gallon covers approximately 200-400 square feet (18.6-37.2 m²)

Optional amendments to boost microbial activity:

• Unsulfured molasses: 1 tablespoon per gallon (15 ml per 4 liters) feeds beneficial bacteria
• Kelp meal: 1 teaspoon per gallon (5 ml per 4 liters) adds trace minerals
• Fish hydrolysate: 1 tablespoon per gallon adds nitrogen and feeds fungi

Water quality matters:

• Municipal water often contains chlorine, which kills beneficial microbes
• Let tap water sit uncovered for 24 hours to off-gas chlorine
• Or use well water, rainwater, or a dechlorinator

Application timing:

• Apply in early morning or late afternoon to avoid UV damage to microbes
• Apply every 2-4 weeks during growing season
• Do not store brewed tea — use within 6 hours for best results