I used to let wood like elm and gum freeze hard in the winter to make it easier to split for firewood. In the case of gum, it would kind of "slab' off, not splitting true to the grain. Might be an interesting experiment w/ elm, notwithstanding the following.
On the other hand, at least in the case of hickory, as far as I'm concerned winter cut white wood is of little or no value because of the investment required to get the bark off.
Be very careful to get all the bark off your elm before you stack it even close to your osage. I don't know why, but I've had a couple or three instances where I stored green off the stump whitewood with osage and had a giant bug infestation. You do NOT want them lil bastids in yer stash, and no amount of pesticide will touch 'em once they get to eating.