seed packets asking for cold frame?

What's the equivalent or alternative to instructions on perennial seed packs asking for cold frame in Spring?

Would this also imply cold soaking, stratification or not? Could I alternatively sow seeds in trays and keep refrigerated until temperature is safe? Thanks

How about winter seed sowing in a milk carton? Cheap, easy, flexible, etc.
http://www.madisoncountymastergardener.org/garden_articles4.htm

Do you keep the plastic cap on the lid? How about holes in the sides of the jug, seems mighty damp inside mine. Thanks