Trees naturally grow vertically, but high winds can cause one to lean and partially uproot. Take a long look at the roots of the tree before trying to straighten it. If the tap root is broken, the tree won't survive. If only surface and side roots are damaged, leaning can be corrected. Attempt it only If the tree is less than 15 to 20 feet tall and the trunk diameter is less than 4 to 5 inches.
Measure the height of the tree. For a 15-foot tree, you'll connect the brace cable to the trunk 7 1/2 feet from the ground.
Cut a 9-inch piece from an old garden hose or inner tube. Run one end of the length of cable through it. This will cushion the tree's bark from the cable.
Wrap the cable around the trunk at the height you calculated in Step 1, resting the hose or inner tube against the bark. Twist and knot the cable snug but not tight.
Walk back from the tree. If it is cabled 7 1/2 feet up, stop at the same distance from the trunk. Set the point of the 24-inch stake at a 45-degree angle back toward the trunk, and drive it into the ground with a hammer.
Run the end of the cable through the eyelet of the stake. Walk back toward the tree, pulling gently until the tree comes vertical. Twist, knot and secure it tightly at the eyelet.
Watch the tree over the next year as roots regrow and the tree anchors in position. If root damage was considerable, you may need to add a second cable for additional support.
Remove and adjust the width of the loop that rests on the trunk bark every 6 months to avoid girdling as the tree expands with normal growth.
Do not try to straighten a large tree by yourself. The torque needed to straighten a mature tree is beyond the skills and equipment of anyone but a professional.