I’ve had my Bonsai for nearly a year and it’s been growing fairly well.

I repotted it nearly five months ago and I’ve noticed that there is white mould growing in the soil and beneath the pot. It doesn’t seem to go away and I’m wondering if maybe it’s because of the cold? I’m in the U.K. and the humidity is low. My Bonsai stays on a sun facing window. Please help, I’m worried it’s rotitng!

In terms of watering, I was told that I should wait until the soil looks and feels dry before adding more water to avoid over watering.

No idea what species you have but if it is one that could be outside I would put it out. I don't think it is anything to worry about. It is probably calcium from your hard water. Vinegar will get rid but keep it off the soil use a toothbrush to remove it. Your watering regime is about right, but make sure that you water thoroughly each time.

Definitely calcium deposits!