I have one begonia rex that I keep in west sun most of the time. I only have west and east windows as I live in the north. My begonia looks... bony. I would like to put in a new pot with new soil but when I pull it out of its pot, it comes out whole and I can't shake the soil out, the roots are incredibly fiberous. I water it when it looks thirsty and or after I stick my finger in the soil and its dry to an inch. What else can I do to make this rex thrive (other than knock a window on my south wall). Or am I just impatient? I've had it for a month and a half now.