Using last year's seeds?

Not sure about cold but I assume it would work. Make sure it is sealed well so moisture does not get in when thawing. I just keep mine in a sealed humidor with a Boveda pac (62%) in it and temperature controlled area (70-75 degrees year round).

The old seeds were from a friend in New York State that I grew up with and have been best buds forever. I barely remember him telling me back in 1974 that he would save all the seeds from a pound of Columbian Gold we bought for $200. About a year ago, we started talking and realizing that we weren’t getting any younger and started to grow them. I am going back to get more this fall !

My personal best auto’s are AK-47 and Blueberry. Best of luck on your grow. Jerry