When to plant seedlings in permanent growing position

I am in the process of germinating some toad lily seeds myself right now and have them in pots in the fridge. I was told by the person who gave them to me, to give them a cold period, before they would sprout!

I have toad lily and blackberry seeds. I am trying to germinate the blackberry seeds too, the same way. Here's what else the person who gave me the toad lily seeds said as well...