I've never dipped my end in anything and my crack is fine! :lol:
I dry my saplings in the attic space over the garage or in the garage itself. It gets blazing hot in summer, cold in winter and damp all year long. I've never had more than a tiny bit of checking (cracks at the end of a drying board) in a sapling.
Saplings are usually not too terribly thick and the lack of large heartwood/sapwood differentials will mean that you won't have much variation in expansion and contraction across the thickness. That's what causes checking, as parts dry faster than others.
One way to not care so much is to leave the stick longer on both ends than you want so you can cut off the checked ends. I've only had one piece of wood check all the way down, and that was a three-foot quarter of an ash log I wanted to turn into a froe club. (no not a social organization for people with large curly hair styles). it was a surface crack because the section of log was still quite thick with all of the sapwood and heartwood intact.
I lived in Michigan for almost 13 years. I know it can get cold. I also know that the winters tend to get very dry. Your garage should be fine. The only problem would be if your sapling gets truly frozen while it is very wet. But that's probably not very likely. You'll probably be fine.
If you do want to dip, some cheapo woodworkers use plain white glue, like Elmers. It's messier to work with, but much, much cheaper. Not sure how well it works as I've not used it. Others just use whatever latex paint they have left lying around in rusting buckets in their garage. The idea is to stop moisture escaping through the ends, which are much more porous and thus more likely to dry faster, and keep all the evaporation coming out of the face of the wood which supposedly will mean it will dry more evenly. That's the theory anyway.
Try a couple of different things, including nothing at all, and see what works.
Good luck!