The soil shouldn't be soaked. More dry on the top of the substrate. The key here is humidity in the air, not so much moisture on the ground (though the soil should be wet up to a point). You'll want to keep it covered, and 100% covered with Saran wrap will do fine.
Also, just as an FYI, I'd pull the worm castings away from the glass. johnny_ftm noted when he was doing his DSM with earthworm castings that algae grew rampant where the castings were in contact with the glass. Push the other substrate between the castings and the glass and it should be fine.
1. Watt [ wot ]: noun -- the SI unit of power, equivalent to one joule per second and equal to the power in a circuit in which a current of one ampere flows across a potential difference of one volt.
2. Per [ pur; unstressed per ]: preposition -- for each; for every.
3. Gallon [ gal-uhn ]: noun -- a common unit of capacity in English-speaking countries, equal to four quarts.
What does this have to do with growing plants?