I used to winter sow and got away from it a few years ago. I decided to plant a few this year. I liked the milk jugs, so got a few of those. I can't remember if you keep the cap on or off? I thought it was supposed to be on in the deep cold and removed after the deep freeze for ventilation and watering. I can't seem to find a reference to this specifically. Mine have the caps on and have been under snow since they went outside. I need to know if I did it wrong, I was going only by memory when I planted. Can someone tell me?