Posted: 30/03/2013 at 08:25
Hi, I am having exactly the same problem as you so would be interested to hear how things progress. I am growing Penstemons on the windowsill (no artificial light) and they are germinating then dying off as seedlings (don't think I've allowed them to get too dry or overwatered). Other seeds are doing fine.
Wonderd if it was getting too cold in the evening so will attempt to re-locate new batch at night if this new batch geminate. Interested to hear your comment about planting in a cold frame so might sow a few more today and try them out in a cooler environment as a test to see if I've been killing them with kindness!