Hi folks, in your experience, is there any point in hanging on to trays full of seeds that I planted about 8 weeks ago with no sign of germination? They are in an unheated greenhouse. I was a bit too keen and think I planted too early. Is it wishful thinking to assume they will just sprout when they are ready? What happens to them when they don't sprout? Do seeds sort of die?? I did tomatoes, chillies, cosmos, dahlias and sweet peas. Not a cheap mistake!! That'll teach me!
At the beginning of March I sowed some Dahlia seeds which I had collected last October/November from seed pods in my own garden. I 'overwintered' them in sealed packets in dry, airtight plastic boxes in my garage. The seeds were sown on multipurpose compost, watered and put in an electric windowsill propagator at a temperature of about 19 deg C. Most of them had not germinated after several weeks and on examination appeared to have rotted.
Interestingly, some Dahlia seeds bought from a commercial company all germinated quickly under exactly the same external conditions.
So, in your case, I don't think the reason is entirely due to the low temperatures in your unheated GH.
As a member of the RHS I raised the question with them. The Horticultural Advisor suggested that I had sown them a little early and they could well benefit from cold chilling (cold stratification) for about two weeks before sowing again. I put them in the fridge and the two weeks is now up so I will sow some more this next week and see what happens (it being later also). I have read that even seeds that do not need chilling may germinate more quickly after a period of cold storage.
You may want to try the chilling before sowing now process. Let me know your results good or bad and we will go from there.