Hello. I could do with some advice on how often to water my phalenopsis, please. I have three small ones, all of them budding and one currently in flower. I live in Sydney and it's winter here. THey're indoors, in bright indirect light, standing on a tray of wet pebbles (though not in the water).

They came potted in terracotta pots with holes punched in the walls. The potting medium is very loose and appears to be chopped up bark of some sort. It seems liable to dryness and to have no soil mixed in. The care labels advised watering every two days. In other places I find advice to water every two to three weeks - that's a lot of difference! I have tended to water every few days, letting them stand in water for about half an hour before removing them.

When they arrived there were plump roots on the surface, with green tips. Now, some of those roots appear wrinkled, as if they have dried out. The rest of the plants appear healthy and they continue to flower. Am I watering them too much? Not often enough? Please help!