Hum, I've managed to germinate all the pomegranate seeds I've tried planting so I don't think they are that hard. I didn't do mine in a plastic bag but placed them on some wick material that was hanging down into some water in a kinda hydroponics set up. I now have 2 small dwarf pomegranate trees and 2 small regular pomegranate trees. I believe mine were probably exposed to some light and germinated anyway but I'm not entirely certain of that I might have kept a couple of them in the dark till they germinated.