Every year, we "straighten up" quite a few trees for various reasons. Trees typically start leaning due to a high wind event, sometimes combined with heavy rains and wet soil. A leaning tree isn't necessarily unhealthy (it really depends on the root condition), but they do look funny in the context of a manicured suburban landscape. This learning spruce tree below made a great case study on straightening tipping trees.
This tree took the cake in terms of size for leaning trees straightened by Heartwood in 2016. This guy was 25-30’ tall, and as you can see it was tipping/leaning a lot. The wet weather in spring (which loosens soil and destabilizes roots systems), combined with strong winds later in the year (which levers trees strongly and pulls on their roots), proved too much for many shallow-rooted spruce trees like this one.
A leaning tree can be saved depending on the severity of the lean and the condition of the tree. Often if the roots are exposed or the lean is too great, there is little that can be done to save a tree. This customer really wanted to save the tree, so we gave it a shot. As far as we know the tree is still healthy!
The uprighting process is not too complicated, as you can see in the second photo. We rigged one rope through a pulley, attached one end to the spruce, attached the other to the poplar, and set up a 5:1 mechanical advantage system. The 5-to-1 is the short yellow rope above the drooping orange line. The mechanical advantage helps create super-human strength to pull the tree up straight, multiplying the force of the person hauling on the line roughly 5 times (though we lose some energy to the friction of the ropes through the pulleys and hardware).
Once straight, we install three poly cables (ropes) to hold the tree in place. In this case, two cables went to posts pounded into the ground to help provide stability on each side. The other cable was attached to the poplar trunk, which is the main support for the spruce.
The biggest concern with leaning trees is whether the roots are healthy and strong enough to attempt to straighten the tree. In this case, the roots were still intact and buried. Beyond the roots, the next concern is what to tether the tree to. In this case we had a sturdy tree that provided me confidence that this could be done. If we had to hold this tree up with only three metal posts, we may have reconsidered our options.
Once the tree is straight expect to leave the cables in for several years at a minimum, especially with a tree of this size. Each tree is unique so there is really no good way to know how long the tree might need support. Over time the cables will just need to be checked for proper tension. When checking the tension, you can always let out the cable a bit and see what happens; if the tree does not move at all when the cables are loosened, it may have reestablished enough root system to stand straight on its own. I wish there was a more exact science to this but there really is not!
We had many successes righting many "ships" last year, but we also had some failures. In any case, we forge on willing to straighten just about any tree out there if the owner wants to give it a shot. I mention this because tree straightening is not always successful, but why not try it if it’s a safe option?