Northern Virginia Soil and Water Conservation District

703-324-1460 TTY 711
12055 Government Center Parkway
Suite 905, Fairfax, VA 22035
Willie Woode
Executive Director

Understanding Tree Roots

Tree roots serve many purposes.

Tree roots anchor the tree in the soil, keeping it straight and stable, and absorb water from the soil. Tree roots also take nutrients and chemicals out of the soil and use them to produce what they need for the tree’s growth, development, and repair.

Taproots do not form on trees planted in our urban landscapes.

Eighty percent of all roots occur in the top 12-36 inches of the soil. In sandy, well drained soils some trees such as oaks and pines develop deep roots, directly beneath the trunk. These are commonly called taproots but are actually deeper roots that help anchor the tree. Most trees never develop taproots, especially when the water table is close to the surface or when the soil is compacted.

Damaging roots on one side of a tree may cause branch die back on that side only OR at random places throughout the crown.

Damaging the roots of a tree causes damage to the tree branches. In some tree species, roots on one side of a tree supply the same side of the crown with water and nutrients absorbed through the roots. If roots on one side of such a tree are injured, branches on that side often will drop leaves. In other tree species, damage on one side of the root system may cause branch death anywhere in the crown of the tree.

Pruning can be harmful to a newly planted tree’s health.

Pruning branches on trees not yet planted does not help a tree grow better or establish a balance between the roots and the canopy. When trees are dug up from the nursery for transplanting, many of the tree’s roots are left in the soil. A newly planted tree needs all the leaves it has to help support the growth of new roots. Pruning trees before planting removes the food-producing factory of a tree, which hurts the tree’s ability to become established.

Symptoms of drought and over watering are the same.

Tree roots need moisture, air, and a favorable temperature regime to function and grow. Tree roots need to be deep enough to avoid sunlight and to stay moist but should be shallow enough to absorb adequate oxygen. When trees are over watered, their roots do not receive enough oxygen to function. As a result, tree leaves wilt, die and fall off. During drought periods, tree roots do not receive enough water to function. As a result, the tree leaves wilt, die, and fall off. Slowly and deeply apply five to eight gallons of water to newly planted and young trees once a week during hot, dry periods.

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