Hans, as a snowmelt plant, growing for a short season then retreating quite early to dormancy, and growing in gravelly soils, I would suggest the following method for Dicentra uniflora seed .... (when you have plants, treat as for frits in the alpine house.).........
Fresh Dicentra seed tends to germinate fairly rapidly, but seed you have now will likely take its time. Winter exposure for the seed pots is called for.... are you familiar with the compost mixture used by Ian Young? (If not you can find it it the BulbLogs) ... basically it is a 2:1:2 mix..(this can be 2 parts gravel, I part leafmould ( or peat if you use that) and 2 parts loam ) but we mostly now use 2 parts gravel 1 part leafmould and 2 parts sand
(good, "sharp" sand that is painful to rub in your hands!) and this would be best for the dicentra, I believe. Sow the seed thinly on the surface of the slightly moist compost, on a layer of sand then dress with gravel and set outside in a frame. Wait for winter to do its work. There should be some growth in Spring....feed with dilute liquid feed and try to keep the plant growing for a s lomg as possible..... it won't get very big, but you must keep it green for as long as you can. when it yellows, allow the pot to dry somewhat but do not allow to become dessicated over summer. Don't prick them out for a year or two, keep feeding them..... that's the best advice I can give..... good luck!
