Just received some seeds from Jelitto (Penstemon cyananthus, mensarum and pinifolius). Does anyone have advice on sowing/germination techniques? Jelitto's guide suggests all benefit from sowing at no more than 5 C, with germination taking place irregularly over a long period. I also picked up Gentiana sino-ornata and "Viola coreana Syletta", which are both listed as rapid germinators, without stratification needs. If anyone has experience germinating the Penstemons and Gentian, I'd be in your debt.
I've only germinated a couple of Penstemons, so no big insights here- I know Alplains list bazillions of them, and some he has as warm germinators, and others needing cold stratification of various length- you could compare your species to his list as one check..
We have good germination of Gentiana sinoornata here by sowing in late winter and leaving the trays outside in the elements and watering if required . The temperature range would be -10C to 20C . I realise its colder at your place but it may still work . The seed is covered in their trays by a thin layer of small stone chips .
I really hope the gentian seed germinates for you because we supply that species to Jelitto