Non-hybrid apples do great from seed. This is a non-graft, so that doesn't apply.
/johnny
These aren’t the apples the tree used to produce before I cut it down. The neighbor seems to think I’m getting the apples the rootstock originally produced.
http://www.gardenguides.com/91099-reproduction-apple-trees.html
Seems to be pretty thorough. Since you don’t really know what type of apple you have your best bet for reproducing that particular one seems to be grafting or just rooting some sprigs.
If you don’t know of any other apple trees nearby planting the seeds would probably work too although they might not be that *exact* variety.
It sounds like what you’ve got is a ‘rootstock’ plant though. And if you like that one enough to eat it if it were me I’d just take cuttings and root them. No need to graft on something tolerant of cold or soil diseases as that’s why things are usually grafted.
Lucky you.
In Oregon, we had an apple tree by our right-of-way fence that had obviously came from a tossed apple core. It had 5 or 6 main stems emerging from a common point, and each of those trunks produced a different type of apple. A couple of them were too sour to use for anything except hog food, so they were sacrificed for the greater good of the remainder.