Ginko, I believe is hardy to
zone 5, also know as the maiden hair
tree (or maiden
tree). The
seeds have to be fresh to have a chance of germination, once they dry out they're dead. I'm sure the mimosa can withstand you
zone 6 winters...just be sure to chip the
seeds before you soak them so they take in water faster. Or you may want to soak them in really hot (not boiling) water overnight they should've swelled, any that are floating means that they have a dead embryo inside, you could try planting them but I've had no luck with them germinating (I used the method for sensitive
plant aka mimosa pudica) I would advise you to maybe keep the
tree in a pot for the first year, and then transplant into the garden, being sure to add mulch and protect it during its first winter. If the m. pudica is the same as the mimosa you are trying to start, then be sure to use a deep pot because it has a very deep taproot. Ok, enough of me blabbing, if you need anything, or if I wasn't clear, just let me know!