What if you harvest a finished Worm Factory tray in the middle of winter when you’re not growing anything? Or you have enough vermicompost that you can’t use it all in your garden at once? Never fear, vermicompost can be stored until you’re ready to use it!
When storing vermicompost it is best to first let it dry a little, so it is damp but not wet. This ensures sufficient air penetration through the material to prevent anaerobic bacteria. Then, store your compost in a non-airtight container. A 5-gallon bucket with lid slightly ajar or with several holes drilled in the lid makes a great storage container. Stored this way, the vermicompost slowly stabilizes in an aerobic environment and has a shelf life of more than three years. Here’s how:
Vermicompost is a mixture of worm castings (worm poop), decomposed organic matter that did not pass through the worm, and partially decomposed organic matter that is still somewhat recognizable. In most situations, castings comprise the bulk of the material, usually around 70-80% of the total, depending on how the compost has been managed and how long the compost has been processed in the system.
The partially decomposed organic material in vermicompost continues to break down during storage. Placing actively decomposing organic materials in an airtight container encourages anaerobic organisms to take over, which can cause a foul smell from plant toxic by-products, but allowing vermicompost to dry halts the decomposition and can cause the material to become impossible to re-wet. This is why you keep it aerated and moist during storage.