Inspired by February's Gardeners' World magazine, I bought 4 orchids from a supermarket to display on a marble topped dresser. They look great, but my record with houseplants is not brilliant. Are they likely to be in orchid compost and, if not, should I re-pot them in orchid compost straight away? Also the pots they are in seem small to me - is this how they like to grow, or should I put them into bigger ones? Many thanks.