I have some "seedling" of D. paradoxa that germinated in about march (I think) and are currenty flowering. They largest plant is about 2 1/2" across. I keep these in a fishtank with a heater keeping water in the bottom at about 30c. The plants get watered when they look a bit dry and are not sitting in water. They are growing in a pet 50:50 peat/perlite mix.
The problem is if you take the plants out to photograph the flowers they close in the cooler air!! AHHH!