Limited value I know as I only do a few trees from seeds and they are my fresh harvested ones. So I can't speak to "tree seeds" in general. But I think the method of storage would determine the viability/shelf life. So I'd want to find out the storage methods used by the supplier.

The USDA/Arbor Research org says the life expectancy of most tree seeds is 1-2 years if stored at ambient temps, up to 3 years if refrigerated, and 5 years if stored frozen. But I'm guessing that frozen tree seeds, just like other seeds, would need to be planted immediately upon thawing so if theirs are frozen, how would they ship to keep them from thawing?

I guess the bottom line is to insist on more viability info from the supplier, some sort of 'guarantee'.

Good luck.

Dave

PS: you might also ask over on the Trees forum here to see if others there have had experience with the particular companies and their quality.