Does Pruning a Tree Reduce Root Growth?

Tree pruning is an important job for gardeners and arborists. People often ask, though, if pruning a tree slows down the growth of its roots. The short answer is no, pruning does not slow down root growth. But wrong or too much pruning can stress a tree and stop its growth in and out of the ground. When done right, pruning helps a tree’s energy go in the right direction and builds a strong, wide root system.

How Pruning Affects Trees

Pruning removes parts of a tree to control growth or shape. It causes the tree to seal off cut areas and stop sap flow there. This redirects energy to other parts of the tree. Moderate pruning invigorates the tree and stimulates new growth. However, overly heavy pruning stresses the tree. It must work harder to seal cuts, regenerate foliage, and transport water and nutrients with a reduced canopy. Severe pruning slows photosynthesis and food production for roots. It can even kill the tree. But thoughtful, careful pruning does not reduce root growth.

How Roots Grow

A tree’s roots and canopy work in balance. Roots supply water and nutrients for foliage growth. In turn the foliage produces food to sustain roots through photosynthesis. If the canopy is pruned the roots respond by growing more small feeder roots. This increases their capacity to supply the renewed canopy. If roots are damaged or restricted, the canopy may grow more foliage to supply food energy to heal and expand the roots. Trees aim for equilibrium between their above and below-ground parts.

Reasons for Pruning

Here are common reasons for pruning trees:

• Remove dead, damaged or diseased wood
• Improve structure and form
• Increase light and air penetration
• Promote flower and fruit production
• Restrict size near buildings or wires
• Improve aesthetics and views

Proper Pruning Technique

Pruning should:

• Preserve the tree’s natural form
• Remove no more than 25% of live foliage
• Make clean cuts at branch collars
• Space out pruning over years
• Avoid topping or heading cuts

Pruning Effects on Roots

With proper pruning technique, roots continue growing actively. Light pruning removes less foliage than the roots can sustain. Moderate pruning balances root loss from cuts with new canopy growth. Over-pruning stresses roots temporarily but they recover as the canopy regenerates. However, severe pruning or root damage can stunt overall growth. The key is pruning in moderation.

Does pruning reduce root growth? Generally no, when done correctly. Roots and canopy are interdependent, so roots respond to pruning by growing more small feeder roots. However, roots can be stunted if too much live wood is removed at once. Proper technique is vital. With thoughtful pruning, trees flourish above and below ground. A pruned tree can have an even more robust root system than an unpruned one.