I think the only issue you would have with putting it in the ground for the natural winter vernalization is a worry that an animal will dig up and eat your seed that you will inadvertently weed it yourself when it comes up. There is actually a very well known
gardening technique for all sorts of seed that need cold stratification which is known as winter sowing. If it were me, I'd probably hold onto the seed until just before the ground was too hard to plant (if the ground freezes) or the beginning of cold weather (here) just to reduce the amount of time an animal had to find it.
There are a lot of people here who've tried their hand at growing
trees from seed so feel free to ask if you have any problems. If you look at the bottom of this
thread we have a list of similar threads. You can find where a lot of other people discuss their own experiences with winter sowing or growing trees from seed. Maybe you'll find them helpful.
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