Why Use Root Trainer Pots?

Nursery pots are recyclable.

While round black nursery pots are the norm, there are specialty pots designed to manipulate the roots in a desirable direction or to get the roots to perform in a certain way. Roots in traditional pots begin to circle around the inner side of the pot when they reach the edge. This becomes a problem when the roots continue in the circular pattern when planted, because the roots may never expand adequately into the surrounding soils or the roots may circle around the plant, eventually girdling it. The goal of root training is to help the plant avoid encircling the pot and to form a more fibrous root ball. Does this Spark an idea?

Air Pruning

One method of root training is air pruning. Some pots have holes in the sides and bottom designed to optimize this kind of pruning. When roots grow, they reach the edge of the pot, emerge though a hole and dry up. They are "pruned" by their contact with open air. When the roots outside the pot die, new rootlets begin to form inside, eventually making the root ball fibrous and dense, making transplanting more successful.

Redirecting Roots

Another way to train roots is to direct the roots downward instead of letting them grow around the inside of the pot. Some pots have vertical ribs to channel the roots downward, while others are square or tiered to prevent root circling. Often these kinds of pot will also have holes in them, so the roots will be directed downward and be air pruned at the same time. This allows the roots inside the pots to avoid circling and to form a more fibrous, dense root system..

Chemical Pruning

Some pots are specially lined with a copper-based chemical that kills the root tip when it comes in contact with it. Copper hydroxide is mixed with latex paint and sprayed into the containers, and a pot treated with this chemical will have turquoise speckles on the inside. Killing the root tips causes the remaining roots to branch and become fibrous. However, a few plants, like azaleas, may be sensitive to the chemical. Such a plant may die or its growth may be inhibited. Thoroughly read the label before using such a pot.

Root Constriction

Some fabric containers are either used in the ground or above ground, and the roots are allowed to escape. However, the fabric has a tight mesh, and when the roots escape they can't continue to expand and eventually will girdle themselves. This restriction elicits the same reaction as other root pruning methods; the roots inside the container will branch and the entire root ball becomes more fibrous. Also, the roots are discouraged from circling around the pot.

References

• Superoots; Effect Of Container Shape on Top Growth and Root Development of Selected Landscape Trees; Hani Alzalzeleh
• Auburn University; Styrene-lined and Copper-coated Containers Affect Production of Dogwood; Thomas J. Brass, et al.; 1999
• Agricultural Marketing; Sustainable Small-Scale Nursery Production; Steve Diver, et al.; 2000