Species needing heat stratification (most of the others)

Option 1: sow in august, keep hot (and dry if you want) until mid-end september, then treat as listed above for species without stratification.

Option 2 (especially when too late for option 1): This was originally suggested to me to be used for Roridula dentata, for which it really worked fine. Some of yo may know my description of making a fire first, extinguishing it with hot water and using the hot water for seed treatment. That works well, but further experiments showed that the fire part was not necessary.
Now, making the fire is fun and the water can later be used to water some tuberous drosera pots to increase the chance of flowering (e.g. for D. erythrorhiza complex species, at least according to some reports I found). However, as it does not make a difference I skip the fire part and use the 30 to 60 seconds in 60 °C warm tab water instead.

The method goes as follows: pack the seeds in some "tea-bags" (e.g. use filter paper from your coffee machine, do not forget to label the seeds), and dump the tea-bags with the seeds into 60 °C for about 30-60 seconds. Let them dry, sow and treat as described for species without stratification.

Here is the short version of the method:
- Pack the seeds in "tea"-bags, do not forget to label them
- Dump the "tea"-bags in 60 °C warm water for 30-60 seconds
- Let the packets dry and sow the seeds


Here is another version of the heat treatment I so far tested only on south african winter growing plant seeds (D. trinervia to be precise) and the experiment needs to be repeated with more species to be more robust: I have access to an oven heated to a certain temperature (for D. trinervia it was 40-41 °C). I packed the seeds in a paper envelope, packed the envelope in a ziplock bag and then everything in the oven for 1 day to 3 weeks. The most seedlings appeared after 1 or 2 weeks treatment, but as already mentioned this needs to be confirmed. I now also have access to a 37 °C warm oven, a temperature which I like even more to mimic the conditions of a Western Australian summer.
Finally I would like to mention that especially species with larger seeds may also germinate in later seasons. So, do not throw the sowing pots away. Just store them somewhere dry and start watering in september again.



Species needing harsher stratification conditions (Drosera lowriei, Drosera ramellosa and probably some others)

As just mentioned above, some species still may not germinate after the heat treatment in their first season. Drosera lowriei and Drosera ramellosa are such species in my experience with about a couple of seedlings in both cases after several years and seed portions of trying. I suspect there may be other such species as well (e.g. Drosera humilis). I do not have that much experience with seeds of some species, which limits the information I can give here.

Now back to Drosera lowriei and Drosera ramellosa which I found to be notoriously difficult to germinate, even different version of the heat treatment did not help that much although I at least saw some germination in later growing seasons. This is not very satisfying for such restless people like me.

After several failed attempts I now can offer this method. At this stage I used it only once for tuberous drosera and it is by no means optimized (concentration, treatment duration, with or without heat treatment up front) and even not yet reproduced, but at least it is something to start with.

Here is what I did:
- Pack the seeds in "tea"-bags, do not forget to label them
- Dump the "tea"-bags in 60 °C warm water for 30-60 seconds (this part may or may not be required - it remains to be tested)
- After cooling dump the "tea"-bags in 2.5 % sodium hypochlorite solution for 30 minutes
- Dump the "tea"-bags in a large volume of water to wash away at least most of the hypochlorite (about 1 hour)
- Let the packets dry and sow the seeds

Sodium hypochlorite is somewhat difficult to get hold of in Germany, but it is sold in some countries like the USA as household bleach. Some of the seeds were already bleached after the 30 minute treatment period, but at least I got far better germination for both D. lowriei and D. ramellosa than ever before.
At this stage I can not tell whether the hot water treatment is necessary or a shorter hypochlorite bath would also be ok or even better. That remains to be tested in later years.

I am sure there are more options for the stratification (like soaking with GA3) but those are the ones I use and which I find quite easy to use even with larger numbers of seeds/species.