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Why Is Root-Pruning Necessary?


Root-bound plants have a cramped rootball that strangles the plant, preventing proper nutrition, water, and air circulation. When this happens, the plant will either need to be moved to a larger pot or have its roots pruned. Tree transplanting into a larger container is more common than root pruning.

However, there are times when repotting a plant into a larger container is no longer possible, and cutting tree roots is the only option left. 

What Is Root Pruning?

The process of slicing through the roots at the drip line of an established tree that will be dug and transplanted is known as root pruning. It promotes the development of new feeder roots around the root ball, which will be transplanted with the tree. A smaller root ball with multiple feeder roots will help the tree adapt to its new location in the ground more quickly.

Older trees that have grown in the ground for a long time have roots that extend far beyond the branches or drip line (the distance at which the branches extend above the ground). The tree uses these long branches to anchor and support itself. However, most of the small feeder roots that give food and nutrients to the tree are growing off the primary roots some distance away from the tree itself.

How Is Pruning Roots Beneficial?

  • Root pruning is very beneficial when repotting a new plant to make potting easier or to encourage more root growth.
  • Another benefit of root pruning is that it slows growth because the plant’s energy is spent regrowing the cut roots rather than growing new top shoots. When the plant is dug up, this helps reduce the root ball’s size.
  • Root pruning can also encourage the growth of more fibrous or hairy roots, which improves nutrient absorption from the soil.
  • Root pruning, also known as root training, is an integral part of the bonsai process.

Long Term Benefits Of Cutting Tree Roots

Root pruning is sometimes used to maintain a dwarf size tree. However, many “dwarf” trees are slow-growing trees. If a dwarf tree begins to grow taller than needed, root pruning will shock it enough to cause it to stop growing tall and focus all of its energy on growing new roots.

You can also use root pruning to encourage the flowering of a fruit tree or a slow-blooming vine-like wisteria. In this case, the plant perceives that it is being attacked and responds by producing flowers and seeds to reproduce.

When potted plants have outgrown their container, and you don’t want to move them, root pruning comes in handy. Trimming the roots and repotting with fresh soil will help control the plant’s growth.

How To Cut The Roots Of A Potted Plant?

Tools you’ll need:

  • Hand cultivator
  • Long knife (if needed)
  • Pruning shears or sharp knife
  • Stick and pronged cultivator
  • Small bag of soil

How To Prune Roots?

Examine The Root Ball

The first step includes examining the roots. However, if the plant is delicate, make sure you don’t pull the plant out of the pot. Instead, slide or gently jiggle the rootball out with your hand at the plant’s base. To separate the soil and roots from the pot, you may need to run a long knife around the perimeter.

Cut Roots

Start with a pair of scissors, a sharp knife, or pruning shears to prune the roots. Remove both roots and soil from the plant’s root ball by cutting around and under it. It’s okay to be a little aggressive when removing both large and small roots. This may appear vicious, as if you are harming your plant, but the plant’s roots can withstand a lot of abuse, and the plant will thank you for it. Cutaway the bottom quarter of the roots for extremely root-bound plants to help regenerate healthy growth.

Remove The Rootball And Loosen It

Gently tease the rootball with your fingers. If the root ball is extremely tangled, loosen the soil and roots around the surface of the root ball with a stick, pronged cultivator, or fork to spread the roots. Instead of continuing to grow in circles and strangling the plant, this encourages the roots to expand into the soil around the ball.

Time For Tree Transplanting

Before repotting, add potting mix to the bottom of the container. Now, repot your plant and fill in the space around the newly trimmed rootball with soil. Ensure that soil reaches all cracks and crannies between the rootball and the container’s sides. Next, move around the sides of the pot using a stick or trowel to make sure you’ve filled all the voids.

Wrapping Up

After you’ve pruned the plant’s roots, it’s time to let the plant rest. If the plant is used to living in a medium or low light environment, you can return it to its original location. However, if the plant requires a lot of direct or indirect sunlight, you will need to give it a week or two to rest in a partially shaded area before keeping it in the sunlight. Plants, too, need healing!