I use lights, but the pots are in a heated propagator which prevents the temperature dropping below 15 C at night. I have not seen this problem in the past. So the night drop in temperature does seem a likely cause.
Markos, looking at your pots I would suggest you sieve the compost ( next time you sow) to get rid of all the larger bits in there. Young root growth will fare better if it doesn't have to negotiate all the lumps and bumps introduced by all that bulky stuff in the compost.
kili
Thanks! Great tip, I did add some vermiculite so that might be too big as well?
A bit of vermiculite is fine when planting seed. Helps with drainage.
'The power of accurate observation .... is commonly called cynicism by those that have not got it.
Posts
I live in west central Scotland - not where that photo is...
'The power of accurate observation .... is commonly called cynicism by those that have not got it.
George Bernard Shaw'