I used to live in the prairies too, several years ago..and I know what you mean about our dead cold winters there.
I saw this article about white fuzzy mold see if the remedies they suggested will work on it.
http://homeguides.sfgate.com/n...
Since your area is colder than mine, maybe you need to give it some extra lighting to increase ambient temps, that way it is not too wet. You may have to wait till late Spring or Summer to be able to bring that out for much needed fresh air, if it survives.
Good luck!
