My real start of the season is still months away but I couldn't resist to put something in the soil already - Tasmanian Black!
One reason I like using rockwool cubes or AeroGardenIf I weren’t so lazy, I would transplant each variety when germination was sufficient instead of waiting for larger groups. That said, laziness hasn’t bitten me yet.
I'd remove those plastic bags, maybe not the main reason why your seedlings are stunted but it probably don't help either. I noticed that over watering, humidity level (too high) or too much light can dramaticaly slow their growth to the point they are just not growing anymore...The bags are perforated so there's still some air exchange. Anyway, if it works like this, it's better then to see them die off. I'm not going to keep them in the bags forever of course. When I see the plantlets develop properly the tent goes off.