How should I store unused castings?
Written by
Olivia Mitchell
Reviewed by
Prof. Samuel Fitzgerald, Ph.D.Utilizing proper storage techniques can keep worm castings microbially active to maximize their functionality. By maintaining the microbial populations that are present, nutrients stay in a plant-ready form for up to one year. I keep mine in breathable containers and maintain ideal temperatures of 40-70°F to minimize the chance of mold formation, while preserving the same active enzymes that promote growth in plants.
Short-Term Storage
- Use burlap sacks allowing air circulation in shaded areas
- Maintain 40-70°F temperatures for 3-month viability
- Check weekly for moisture using wrung-out sponge test
Long-Term Storage
- Freeze in vacuum-sealed bags for 6-month preservation
- Thaw gradually at room temperature before use
- Avoid repeated freezing cycles to protect microbes
Container Selection
- Wooden crates permit ideal oxygen exchange
- Plastic totes need ventilation holes drilled every 6 inches
- Avoid metal containers causing temperature fluctuations
Temperature control is important. Microbial growth ceases when temperatures fall below 40 degrees Fahrenheit, and its growth is significantly slower above 70 degrees Fahrenheit. My garage storage remains in this range throughout the year. Basements provide excellent storage between 55°F and 65°F. Do not use attics or sheds, as they are subject to wide temperature variations.
It is imperative to label containers with the harvesting date and a pertinent description. I write this on the bags with a felt-tip pen. Keep track of the storage time, as the potency begins to decrease after six months. The freshness tests include an earthy smell and a crumbly texture. Discard when any smell of ammonia appears.
Moisten dried castings with non-chlorinated water, such as rainwater or dechlorinated tap water. Spread thinly and mix well. After a 48-hour hydration period, the stored castings regained their full vigor. Never soak completely, as this will drown aerobic microbes.
Read the full article: Unlocking the Benefits of Worm Castings
