New to begonias, got one for my birthday last year and it's been doing fine. Today when I went to water it, I noticed that there were white spots all over the soil. I'm hoping it's not fungus and that it's maybe mineral buildup from our hard water. But does anyone have a clue on what's going on here? More info: I usually keep it by our south facing back door on a shelf. I try to water it whenever the soil feels dried out and it feels lighter, but sometimes I do miss waterings. It's probably in need of a better spot for sunlight, but I've not been able to find something better or a way to put it in a window out of reach of my cat.

