NORTH FLORIDA — Planting trees and shrubs too deep is a common cause for plant decline or death. In some cases, it only takes planting the roots a few inches too deep to stunt or kill a nice tree or shrub.
There are two ways that deep planting results in decline and/or death of landscape plants. It suffocates roots and rots the base of the trunks.
Tree and shrub roots must have oxygen. Roots grow and live where there is adequate oxygen. As a result of suddenly being placed too deep in the ground, the roots slowly suffocate, die and decay. It can take months to a few years for plants to show symptoms that there is a problem. By then, it’s too late to undo or to correct the problem.
In addition to root suffocation, the lower part of the plant’s trunk begins to rot as a result of being planted too deep. The trunk is supposed to be exposed to air, not covered with soil. As a result of being covered with soil, the bark and wood begin to rot and the plant’s vascular system becomes compromised.
Sugars manufactured in the leaves through photosynthesis are the plant’s food. These sugars move down to “feed” the roots through the inner bark (phloem). As the soil-covered bark and phloem decay, the movement of these sugars is decreased and the roots slowly starve. Again, the resulting plant decline is usually slow.
To prevent planting depth problems with trees and shrubs, follow these planting guidelines.
Before planting, find the point where the top-most main root emerges from the plant’s trunk. This point is called the trunk flare, as the trunk usually suddenly gains diameter (flares out) at the point of main root attachment.
Because many plants will already be too deep in the container, you may have to remove the uppermost potting medium before finding one or more main roots.
The main roots I’m referring to will be comparable in diameter to some of the plant’s main limbs in diameter. If all you’re finding are small fibrous roots, you’ll have to keep digging until you uncover at least one of the main roots.
Next, dig a hole just deep enough to allow the tree or shrub to be placed in its new hole so that this uppermost main root is at the soil surface, level with the surrounding grade after the plant has been planted. It’s best to err on the side of planting too shallow versus too deep.
More information on how to plant trees and shrubs correctly is available through these UF/IFAS Extension links. https://edis.ifas.ufl.edu/pdf/EP/EP39000.pdf https://edis.ifas.ufl.edu/pdf%5CEP%5CEP31400.pdf