Posted: 09/05/2013 at 22:25
I think arid al is right about not too much care. hardy plants never need heat, they wouldn't get it naturally. They need sowing at the right time which is when they drop of the plant. Then leaving to get on with whatever it is they do for however many months they do it. Most will germinate when conditions are right.
You can get caught out. I sowed a Clematis ladahkii (may not has spelled that right) last autumn, it must have germinated in a few days and I didn't notice, the leaves got frosted before I put it under cover and I thought it had had it. Come spring it's growing again and looks fine.