Tree Root Fallacies (and Facts)

4 Fallacies (and Facts) About Tree Roots

Know a lot about tree roots? Many people think they do, but instead, they simply believe what they’ve heard without studying science and the facts behind these complex structures. This can lead to poor decisions about how to care for and maintain trees. Their survival depends on proper maintenance and early detection of health problems, like dehydration, disease, and pests.

Here are four popular fallacies about tree roots along with the facts.

Fallacy 1: All trees have a single tap root

False. The fact is that most trees do have a tap root during their early seedling stage. This tap root eventually grows into feeder roots that grow laterally outward to seek water.

Seedlings grow roots directly below their trunk when they are planted in deep, well-drained soil. Because these roots are directly below the trunk people often mistake them with vegetable tap roots that grow below the seedling.

Deep roots are rarely grown when the seedling is planted in shallow soil. Trees develop root mats to survive in these shallow soil depth conditions.

Fallacy 2: Canopy dieback happens on the same side as damaged roots

False. Dieback refers to the gradual deterioration of health in trees, sometimes leading to tree death. The fact is that canopy dieback often happens on the same side of damaged roots, but not always.

Mahogany and oak trees have root systems that supply water and nutrients to the same side of the tree. These trees can have dieback occur on the same side as damaged roots.

However, maple trees don’t always experience canopy dieback on the same side as their damaged roots. Because of this, maple trees are less predictable. Branch death can happen at any spot on the tree, yet its location may not indicate where the root damage is found.

Fallacy 3: A tree’s root system mirror its trunk and branches

False. The fact is that, for trees in the upper Midwest, most of their roots are in the top 24 inches of soil. These roots are often 2-3 times in width than the part of the tree visible above ground.

While a tree’s crown is upright and spreading outward, its root system is typically shaped more like a flat saucer rather than the opposite side of a dumbbell shape that is visible above ground.

Fallacy 4: Deeper roots mean more water and nutrients

False. Sometimes a tree will send out deeper roots to search for water and nutrients, but this is rare. As stated above, most of its roots will be found in the upper 24 inches of soil.

The tree’s more fragile fine roots supply most of the water and nutrient uptake. These finer roots are most critical to the tree’s survival, and they are often found in the very top layers of soil.

However, these roots in the upper soil layers are most vulnerable to damage due to dehydration and soil compression. If these water and nutrient-absorbing roots are lost it can lead to complications and death.