Ok so sometimes you will get those seeds that just dont germinate whatever you try, this is where scuffing comes in (i only suggest this if youve tryed everything else). What scuffing does is wear down the outside shell of the seed to allow it to take in water easier and sprout its tap root. We do this because some seeds have thicker/tougher outer shells than other which may prevent the germination process from happening (or slow it down alot). Easiest way to do this is get a small box (filter packet or match box) and line the inside with sandpaper, then put your seeds which you are having trouble with inside and shake it for a minute or 2 until the outer shell looks "scuffed" hence the name scuffing. Plant directly into drained soil and cover with cling film, hopefully in a few days it will have germinated good luck
Interesting... I'm thinking this pretty much mimics nature as seeds would naturally get scruffed if left alone in their natural environment.