I want to send somebody in Wisconsin some seeds, but I am afraid they may freeze; if I wrap them well in bubble wrap, could I send them regular mail, or should I send them priority 2 days?
Will seeds freeze in the mail?
Provided your seeds have a low humidity - 5% or less - they will positively benefit by being frozen! After all, that's what happens to seeds outdoors over Winter...
With some varieties, cold storage is essential to trick them into life - to ensure successful germination next year.
Seedbanks worldwide keep rare seeds in freezers, to ensure their survival ten years or several decades later.
But (a big but) their humidity must be low. Or else, yes, freezing will harm them.
Polywrap is a help but won't protect seeds from a prolonged chill.
I've many times sent seeds from here (think our winter temperatures) in Winter, and they have always arrived "alive". ;) I don't think cold is such a problem, and seeds rarely are moist or anything if they are stored and cleaned right.
Thanks, Evert and John. I think they will be fine because they are definitely dry.