Here are some notes passed on to me by a friend about a low cost humidification technique which works better than humidifiers or
bubblers or handspraying. I've seen it mentioned before, but from the number of people posting notes about what kind of humidifier
to get, not many people seem to be using it.
The trick is using Perlite which is a porous volcanic rock (which you can find at any nursery). It looks like little styrofoam beads
and works like magic.
Here is what you do. In your empty terrarium, pour in an inch or so layer of perlite. In most cases, sterilizing the perlite is NOT
necessary. Pour in some water so that it comes within about 1/2 inch or so of the top of the perlite. Don't let the water level get
higher than this or the cakes may get a bit soggy.
You can put the mushroom cakes directly on the perlite (in which case the mushrooms that form at the bases of the cakes can be a bit
waterlogged). Or, you can put them on jar tops or anything else so that they don't directly contact the perlite.
If the water level gets too low, add a little bit more (by pouring it in at the side of the terrarium). You only need 1/4 to 1/2 inch
of water (assuming a 1 inch layer or perlite). (NOTE: You won't need to do this very often -- less than once a week).
Put the top on the terrarium. It is probably a good idea to 'fan' the terrarium once a day so that carbon dioxide doesn't build up down
where the cakes are.
If it makes you feel better, spray the terrarium when you first add the cakes, but this is apparently not necessary.
TIP: If you don't have your cakes directly on the perlite and they seem a bit 'exhausted' after their first flush, put them directly on
the Perlite for a few days. The mycelium will soak up water and rejuvenate itself.
How does it work?
Perlite wicks/soaks up the water. So, the tiny micropores in the perlite which is above the waterline provide a huge surface area for
the water to evaporate. Unlike sprayers and humidifiers all of the vapor in the air is in tiny droplets just like real natural humidity.
The humidity in terrarium will quickly get to > 95%.
I have seen a note on the net suggesting that you get added infection control by adding a small amount of Hydrogen Peroxide to the water.
Note about yields:
My friend who has grown a number of gourmet and medicinal mushrooms, says that his yields were consistently better than when using
humidifiers or bubblers.