Hi Lori,

Welcome to the wacky world of begonias. While I will agree begonias like humidity, most can get by just fine with normal household humidity (nothing extra). There are some fussy begonias that need lots of humidity so you would be better served with a terrarium. For your begonias you shouldn't need anything extraordinary. Just don't place them over a heat vent and forget to water them.

As for mildew, I think cool temperatures is what causes outbreaks. For instance in summer I rarely see mildew on begonias despite watering and misting or days of rain. But once the temps dip into the 40's and 50's then mildew will rear its ugly head. Some begonias are a lot more susceptible to mildew than others. Some canes (mallets and polka dot ones) and rexes are the worst when it comes to mildew. Keeping them sprayed with some kind of fungicide when outbreaks occur or before they occur helps the most.

Your first begonia looks like Silvermist.

Thank you for the reply! Nice to know I can stop obsessively misting. (-:

Do you have a recommendation for a preventative fungicide?

Milstop is the fungicide I am using now. Works pretty good but is a bit expensive although you will get a very large size bucket of it.

Pick off the worst leaves and stay on top of the mildew since it can eventually kill the plant. Watch the stems as well as the leaves. Warm air should be a great ally as well.