It’s not the species. It’s not the soil. It’s not the pest pressure. The most common cause of new-tree failure is planting depth.
If a tree fails in the first 3–5 years after planting, the cause is almost always one of three things: planting depth, soil contact, or watering. Of those three, planting depth is the one that produces the most failures and the one that’s most often gotten wrong by well-meaning homeowners and unqualified landscapers.
View from the Field · Paul Biester · Tree Awareness
“Proper planting depth is essential for healthy plant growth because it directly affects root development, stability, and access to water and nutrients. When a plant is set too deep, its roots and stem can suffocate or rot. When planted too shallow, roots may dry out or fail to anchor the plant securely. Planting at the correct depth allows roots to spread naturally, supports strong early growth, and helps the plant adapt more easily to its environment.”Paul Biester · NJ LTE #408
Too-deep is the more common mistake. The root flare — the place where the trunk widens at the base into the major buttress roots — is the part of the tree that’s designed to be exposed to air. When it’s buried, three things go wrong simultaneously.
The bark suffocates. Trunk bark is not designed for soil contact. Held against soil moisture continuously, it stays wet, attracts decay fungi, and eventually fails. The tree develops basal rot from the outside in.
Adventitious roots form. The trunk responds to soil contact by sending out small surface roots from the buried bark. These roots circle the trunk in the soil layer above the actual root system, eventually girdling the tree from above.
The root system hypoxia-stresses. The actual root system, properly placed, is below the soil surface. When the tree is set too deep, the proper roots are now too far below the surface and don’t get adequate oxygen.
The combined effect: a tree that may live 5–10 years before declining noticeably, by which point the planting mistake is forgotten and the failure looks like “just one of those things.”
Less common but more obvious. The root system is exposed to drying air, root anchorage is inadequate, the tree is unstable in wind. Failure mode is faster — usually within the first growing season.
Find the root flare, and plant so the root flare sits at or just above grade.
On a balled-and-burlapped tree from a nursery, this is more involved than it sounds. Many B&B trees come from the nursery already with several inches of soil over the root flare — sometimes as much as 6–8 inches. You have to dig the top of the root ball before you set it, finding where the flare actually is, and then plant that at grade rather than planting the top of the burlap at grade.
Standard sequence:
A “mulch volcano” — the cone of mulch piled directly against the trunk — produces the same suffocation, adventitious-root, and decay problems as planting too deep. Even if the tree was planted correctly, an annual mulch volcano slowly buries the root flare and reproduces the failure mode at the surface.
The right mulch pattern is a donut, not a volcano. 2–3 inches deep, several feet wide, with a clear ring around the trunk so the flare stays exposed.
Sometimes. If the tree was planted within the last 1–2 years, careful re-excavation of the root flare can buy a recovery window. Air-spading is the right tool. After air-spading, the soil grade is permanently reset to expose the flare.
If the tree has been buried for 5+ years, adventitious girdling roots have usually formed, and the recovery rate drops considerably. The honest call at that point is often replacement.
Most homeowners spend more time researching which species to plant than they spend on how to plant it correctly. The species choice does matter. The planting technique matters more.
If you’re planting a new tree this season, the planting depth question is worth getting professional input on. Schedule with Plant Healthcare →
