Finally, I potted the bundle in a mixture of about 70% pumice, 10% perlite and 15% potting soil. I buried the bundle deeper than I will end up having the tree so that the slugs cant girdle the tree as easily and so that the flare that can kind of be seen in the picture might grow more roots. I added a quarter to the pictures for a sesne of scale.
In the future, if all goes well, I hope to spread out the cluster of branches a bit so that they dont shade each other out.