Summer or winter storms often blow over otherwise healthy trees. Here is a review of the basics of righting trees that lean or have fallen.
The first task is to shovel out a space under the root ball so it can fall back into place when the tree is pulled upright. Even if you can’t see a void under the root ball, dig underneath to remove soil that was disturbed as the tree fell. If you see broken roots, clip them cleanly with pruners. Use very thick padding under the rope or chain you wrap around the trunk in order to pull on the tree.
Once the tree is upright, tamp the soil around it with your shoes and water it thoroughly. This settles the soil into place. Once the tree is straight, you have to keep it that way for several years. If it is six to ten feet tall, drive a sturdy six-foot long stake two feet from the trunk on each side of the tree. Loop one inch wide nylon belting loosely around the trunk and stake. The support should be loose enough to allow some swaying but not so loose that the tree can fall again.
If the tree is taller than ten feet, use three strong stakes driven into undisturbed soil and connected to the tree with wire connected to nylon belting. Again, the guying should be loose enough to allow some swaying by the trunk. The latest research has found that using water hose to pad guy wires can result in great harm to tree bark. Nylon belting one to two inches wide is a better material for holding the tree upright.
Whichever system you choose, it should be left in place only a year or two. The best way to attain good root growth is to spread mulch at least four feet from the trunk in all directions and keep the tree watered in summer.