mulching Cover the backfill soil (and any surface amendments) with a 3”–4”-thick layer of shredded bark mulch, tapering down on the rootball to 0”-thick at the tree trunk (i.e., so that the mulch is not in contact with the bark, thereby preventing fungal diseases from moisture trapped against the tree).
This mulching can be extended into the surrounding garden area to serve the surrounding plants, of course.