Large Crabapple Cutting

I recently trunk-chopped a crabapple tree and decided it wouldn't be a bad idea to attempt to root it. The cutting is about two inches wide, give or take. It has been about a month since I potted it into a shallow container of mostly coarse pumice. I have kept it watered and protected from strong wind and frost (although I believe neither would have hurt). 

Here is the cutting as of today. It actually looks healthy, pushing growth and covered with leaves. I can envision its survival but I've been told that just because it looks good does NOT necessarily mean that things below the soil things actually are good. For now all I can do is baby it and hope that it can manage to put on some root growth.