Seed germination guide Part 1
Some general information up front:
I sow the seeds in small pots (5 cm round pots) and repot the seedlings in larger pots once they appear. This saves a lot of space when sowing the seeds and I also made the observation that the seedlings developed faster after I repotted them (compared to sowing them directly in the larger pot). This process works well for many winter growing drosera species as they initially have just short roots and can be placed on fresh substrate easily. Exceptions for this are mainly Drosera menziesii subspecies and Drosera bicolor. These species produce first an up to 1 cm long fine root and only after that their first leaves. Repotting these species requires much patience if there are too many fibers in the top layer of the substrate. Thus, using a higher percentage of sand in the sowing medium for this species is a good idea to speed up the repotting of these species. It sounds complicated but it gets routine quickly.
The seedlings are repotted into 7 cm deep pots. This pot size may actually not be deep enough for some species, even in their first season (e.g. some Drosera stolonifera may need a deeper pot at the end of the season) but it is sufficient in more than 95% of the species. If I happen to find a pot which a shoot for tuber production which grows out of the pot, I put some substrate into a (larger+)deeper pot, place the pot with the seedlings inside and stabilize with more substrate. The idea behind this is to avoid tubers being produced outside the pot as the shoots and tubers may get damaged in that situation easily.
Once the seedlings are repotted, I treat them the same way as the adults. They get watered by the tray method, as much light as possible and I try to offer a temperature between 5 and 15 °C which is unfortunately not always possible in my setup. One should avoid significantly higher temperatures and long light periods as both may induce dormancy. As a consequence, the tubers after the first season can be quite small and many may not survive the first summer (probably due to desiccation). In case of some species I observed losses during the first summer which I suspect were due to desiccation in the top substrate layer. As stated above, I treated the pot with the seedling tubers the same way as I treat the larger plants: once the plants have died back, I let the top layer of the substrate dry and then I place the pots in a cool and dark spot. No watering until either new growth appears. This summer I started to spray some water every other week which seems to be beneficial.
Finally, I will come to the most important question: how can one convince the seeds to germinate? It actually is in most cases not really difficult. The tuberous winter growing drosera can be divided into two main groups. Most require some kind of stratification, but some do not. I will start with the ones which do not need any treatment:
Species without need for stratification (Drosera macrantha ssp. planchonii, Drosera peltata plus close relatives, Drosera auriculata)
Sow the seeds in september, keep wet and at natural (shortening) day length. Seeds will germinate when light period is appropriate, mostly from october to december.