My houseplant has some white mould on the soil which has developed over the last two days, is this bad for it? If so what should I do about it? I have another identical plant in the house which is fine,both are from the same shop bought at the same time (about 6 months ago) and I have changed nothing before the moud appeared. I don't know what type of plant it is, it's a bit like a spider plant but with a stiff 8'' tall woody stem and the leaves are darker, it's about 18'' tall in all. Thanks!
Was the soil overdamp? Have you overwatered it? Houseplants are best watered from below not from the top. If you have been watering from the top you might of overwatered it in which case the soil can get mouldy looking.
The mould is probably because the plant is warm and moist. Put some gravel or sand over the soil and this should help, and as already suggested water into the drip tray rather than onto the soil.
It sounds like your plant could be a Dracaena from your discription. As the mould is only on the compost, it should'nt be too much of a problem but may hinder drainage by causing a crust on the surfice. You could get rid of this by scraping it off with a knife, then fluff up the remaining soil and top up with fresh compost as nessessary.