Step 4: Fill the jars
Once your substrate is well mixed and moist, begin filling your prepared jars with the substrate. Don't pack the mixture down, just loosely fill the jar.
Leave about 1/2 inch of space between the substrate and the top of the jar. I just filled my jars up to the threading for the lid.
Be sure to wipe up any moisture/substrate on the 1/2" inside and outside the jar.
Fill the rest of the jar with dry vermiculite. This is to make a barrier between the substrate and contaminants in the air.