Large Boxed Tree Needs Extra Help

Q. Should a newly planted 36" boxed purple robe black locust tree have it's nursery stake removed? I sent you a picture of it.

Readers Purple Robe Black Locust staked.

A. Larger trees need their roots stabilized for one to two growing seasons and then the stakes removed. In your case the tree has poor trunk strength since the trunk has no taper to it and the trunk will snap in high winds.

            Immobilize the roots by re-staking the tree. Let side branches develop along the trunk to improve trunk taper and strengthen it. Normally, a tree with good trunk taper can have its stakes removed after one to two growing seasons. A tree with poor trunk taper will require a longer period of staking to strengthen the trunk AND give it solid rooting into the surrounding soil.

            Allowing side branches to grow along the trunk helps promote taper in the trunk reducing its need for staking after one season.

            Ideally, the tree should have small stems growing from the trunk covered in leaves, removing them only when they reach about pencil diameter. This increases stem taper, reduces the possibility of shear or snapping in high winds. 

            Trees also need to “sway” in the wind. This swaying or movement of the trunk from side to side also helps to develop taper in the trunk. But the roots of the tree need to hold the trunk in place at the bottom.

            This tree will need to be staked for awhile to keep the trunk from snapping. Probably at least one season. I would probably restake the tree with either two or three stakes to support the trunk and keep it from bending to the point where it could snap and immobilize the roots.

Large trees usually need stakes to support the trunk. The stakes should be driven deep enough so that they are in solid soil. The support from the stakes should be low enough to allow the top of the tree to move but keep the rootball from moving.

            Two methods used for re-staking include a two to three stake method with the stakes driven into the solid soil beneath the rootball. The other way is to use guy wires to stabilize the tree. I supplied pictures that I will also post on my blog.

            This next year let small branches grow from the trunk if they develop. These will increase the strength of the trunk and help reduce sun damage to it as well. Remove older branches from the trunk when they get larger than a pencil in diameter. Cut them off flush with the trunk. Do not use pruning paint.