Hi, for one thing, bougies do like to get dry between waterings, but if they're not in the right soil, it won't help much. Pebbles don't belong on top of the soil, but completely mixed in with it, to the extent that they make up most of it, with organics (compost, orchid bark, not peaty potting soil) being only a very small part, so water flows right through and, of course, you may have to water more often in summer, but with fewer consequences. You shouldn't have mold on a dry mix! How's the air circulation there - I hope you're not trying to grow it in an aquarium. Is it getting a lot of intense light all day long? Is it in a ceramic container glazed on the inside (much better to be in something like terra cotta)? A little more information would help. But do remember that now your tree may be having it's annual rest for a few weeks, not true dormancy, but lack of growth and a need for less frequent watering (until about February - less frequent, though of course still needing water at some point).