I just sowed a flat of penstemonoides a couple of weeks ago here in SoCal. Just sown outside, in shadehouse,no bottom heat, no problem. I would imagine your temps may already be cooler there than here and Rich is in your area and would know more about that....

I would wait until late February or early March, as the lengthening days and rising temperatures would encourage the germinated seedlings to grow. Over-wintering seedlings in a cold greenhouse is not always a good idea, as they can easily rot.

Thanks, Robin. Unfortunately, I have already sown some of my newly collected seed. I should be able to get a good amount of growth over the next two months since our weather is usually warm during the day until mid-December and my greenhouse does not cool off that much at night. If these plants do fail, I will plant again in mid-March.