Drosera intermedia winter resting bud or hibernaculum. In response to dry conditions, temperature or light cues, the plant forms these masses of small leaves that protect the apex from desiccation. Plants in this state should be kept drier and cooler. D. intermedia from temperate regions could easily spend half the year in hibernaculum. The tropical forms are less likely to form go dormant and form hibernacula.

Drosera intermedia is found in shallow water in bogs and seeps of eastern North America, Europe, and high elevations in South America. The North American and European varieties require a definite winter season to survive long term. You should consider growing them outside year round if you live in their natural range. If you want to grow the North American and European varieties in a terrarium, grow the plants as annuals or put them outside or some cold place when they form hybernacula.

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 hybernacula. 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 hybernacula. 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 doesn't form hybernacula even during freezing weather.

Seeds of the temperate Drosera intermedia need a "winter" to germinate. The best way to start and to grow this species is to give it the seasons it expects when it expects them. If you get the plants out of season-phase they can go dormant on you and you could loose them or at least not be able to enjoy them for months if not a year. If you live in an area they could grow naturally, plant the seeds during the winter or very early spring and allow the seeds to sprout naturally outside. This way they will be in proper season-phase and they will have enough time to get large enough to survive the next winter.

If it isn't practical for you to grown them outside, there is an alternative. The usual way to give the seed a winter is to give the seeds a few weeks of damp cold stratification. You can put pots planted with the seeds in the refrigerator for 4 weeks. An alternative is to put the seeds in a small plastic bag with damp peat or finely chopped sphagnum moss in the refrigerator. The seeds and moss can be carefully spread over the surface of the soil in a pot after stratification.

Seeds of the Cuba and South American forms do not require stratification before they will germinate.

No matter how you handle stratification, the seeds should not be buried when you want them to germinate. A pot with a 50:50 mix of peat and sand usually works well.

D. intermedia likes short pots to be close to if not at the water level. They don't have much in the way of roots. You can use a standard 50:50 mix of peat and sand although using 100% peat may give better results depending on the growing conditions. Dormant plants should be kept damp but not wet.