Dendrobium NOID help required

[Hedge]

Hi in the last three months I have branched out from phals and the odd sympodial cym or odonto type of orchid and purchased these two Dendrobiums at a local supermarket. Are these the type that need a winter rest and drying off, or should I keep them moist all year.

The yellow one is in flower now, the purple one was producing a new spikw but due to the fact we had no heating or hot water for a week up to Christmas Eve, it got a bit cold and the new buds have died at the infant stage.