An excellent option for terrariums is to grow the Drosera intermedia forms from Cuba or South America. Drosera intermedia "Cuba" and "Mt. Romaima, Venezuela" and I presume other South American varieties do not form or rarely form hibernacula. The "Cuba" form tends to be more like an annual and bloom itself to death unless you remove most of the flower stalks. A small percentage of the "Cuba" plants may form hibernacula. Select the form that works best for you. The "Mt. Romaima, Venezuela" form is the easiest Drosera intermedia to grow in a terrarium or cool greenhouse and does not form hibernacula even during freezing weather.