Q.magnolia won’t flower
The tree hasn’t flowered in 2 seasons until this year when it had a lot of blossoms that shriveled and fell off. Then it lost its leaves, which are now coming back slowly. What is wrong with this 4 yr. old tree?
I also garden in zone 4 and have nearly the same situation with my Star Magnolia.
I believe this to be environmental issues with the severe cold winters we have experienced and a few late spring cold snaps. These cold temperatures the hit when the tree is budding can kill off all the flowers.
I would make sure the tree is as healthy as possible and hope for more flowers next spring.
Here is a link.