My guess is it will just take longer with the hull left on as it will need to decompose. I have black walnuts all over the place and they sprout all over my yard. I think the squirrels do a lot of the "planting". The ones on the ground now have lost their hulls over the winter and the furry gardeners have been busy. Seedlings will start popping up about the middle of June but I don't know how long those nuts have been in the ground. If you'd like to have some without hulls that have been stratified I'd be glad to send you some. Hope this helps. Ellen

Ya there is a black walnut tree at my cottage, so we grabbed a few of the nuts to try to get a tree at our home, put them in the ground last fall.

can you sprout the walnuts bought from the store, or are they heated to prevent this?

http://www.ext.nodak.edu/extnews/hortiscope/tree/walnut.htm
This link mentions all sorts of things about growing black walnuts. Beware, walnut trees produce a kind of toxin that affects the growth of some other plants. It does not matter if you take the husk off or not. The husk might even help the plants grow.

As long as the nuts are not treated in any way, they should grow from the store. However, they do seem much different from the ones we get off the trees and are newly dried. I did read an account of someone growing them from the store as well as pistacios. (Any pistacio I ever got was dried and salted and often dyed red, so I wondered...)

The nuts should not be too difficult to grow. Around here so many fall to the ground and even seem to be buried by squirrels. However, the squirrels may also dig them up. ;)