Brew balanced compost tea for thriving gardens. Choose strength, volume, and booster options with confidence. Get clear measurements, then brew, strain, and apply safely.
| Batch Volume | Water (L) | Compost (L) | Compost (kg) | Molasses @ 5 mL/L |
|---|---|---|---|---|
| 10 L | 10.00 | 1.00 | 0.60 | 50 mL |
| 20 L | 20.00 | 2.00 | 1.20 | 100 mL |
| 5 gal (≈ 18.93 L) | 18.93 | 1.89 | 1.14 | 95 mL |
| 10 gal (≈ 37.85 L) | 37.85 | 3.79 | 2.27 | 189 mL |
A brewing ratio translates a goal like “mild” or “strong” into repeatable inputs. In compost tea, the ratio influences microbial density, nutrient concentration, and how safely the tea can be applied. Too weak may underperform, while too strong can clog sprayers, smell anaerobic, or stress tender foliage. This calculator turns your batch volume into a measured compost dose so you can dial strength consistently across seasons.
Gardeners often switch between liters, milliliters, and gallons depending on containers. Converting everything to liters simplifies scaling because the dose per liter stays constant as the batch grows. For example, doubling water volume doubles compost mass, which keeps the ratio stable. If you keep notes, record the container size, unit, and final dose so you can reproduce the same results with different buckets or sprayers.
Presets are practical starting points: a mild mix for seedlings, a balanced mix for routine soil drenching, and a stronger mix for mature beds. A custom 1:X ratio gives finer control: 1:20 yields a richer brew than 1:30 because each liter contains more compost. When your compost is very active or you add boosters, it can be smart to nudge the ratio weaker to avoid foam, odor, and filter buildup.
“One scoop” can vary dramatically with moisture and particle size. Worm castings tend to be denser and finer, while leaf mold can be fluffy and light. The calculator lets you pick a material and adjust density so gram-based targets match your actual measuring method. If your compost is wet, compacted, or screened fine, use a higher density; if it is airy or chunky, use a lower density.
Ratio is only one input; oxygen and time decide whether microbes thrive. Aerated batches commonly run 12–24 hours with steady bubbling, while non-aerated soaks may run longer but need careful smell checks. Keep water dechlorinated, maintain moderate temperatures, and strain well for foliar use. If the tea develops a sour odor or slimy foam, reduce strength, shorten brew time, and improve aeration.
Start with a balanced preset (commonly near 1:25). It provides noticeable activity without being overly concentrated, and it scales easily to different batch sizes.
This tool is tuned for gardening tea mixes such as compost or nutrient tea. For drinkable herbal tea, follow food-safe guidelines and specific brew instructions for the plant material.
Density converts volume scoops to grams. Wet, fine compost packs heavier than fluffy leaf mold. Using the right density improves repeatability between batches and reduces “mystery strength” swings.
No. Boosters can accelerate microbial growth but also increase foaming, odor risk, and sprayer clogging. Use them only when you can aerate well and apply promptly.
Apply as soon as practical, ideally within a few hours after bubbling stops. Fresh tea has the most active biology, and delays can reduce oxygen and shift microbial balance.
Bad odors often indicate low oxygen. Brew a weaker mix, shorten time, increase aeration, and keep temperatures moderate. Also avoid overfeeding sugars and clean the vessel between batches.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.