colander and large particle soil...... too much?

[bonsaiDerek]

I have some recently collected ponderosa that I'm potting into a large particle size mix of pumice, lava, and pine bark. Would it be too much aeration/ drying out to put these trees into colanders with this soil mix?

 

[bonsaiDerek]

so far they seem to be doing fine, what about for winter storage? should i put the colander into a slightly larger bowl to keep the soil from drying out to easily?