Should we mulch under our magnolia tree or will the exposed roots rot?
Magnolias and Mulching
Certified GKH Gardening Expert
Either way will be fine. There will be no harm in mulching the root area, but they will be fine without it as well.
This article will give you more information on magnolia care: https://www.gardeningknowhow.com/ornamental/trees/magnolia/magnolia-tree-care.htm