Part of a hope-based network
restoring and enjoying the Mahurangi

Editor Cimino Cole

Cimino 17 November 2009

It’s Okay to Mock: A crude mock-up of the eNZopen™ hybrid open-ground container concept. Photographer Jonathan Barran

There are no end of alternatives.

The landscaping industry in particular, and particularly in the United States, has spawned myriad containers designed to prevent root circling, the best known of which are the various root trainers.

To prevent or reduce root circling, the following mechanisms are employed:

• • Toxic container linings
• • Vertical grooves to ‘train’ roots downward
• • Air ‘pruning’
• • Fabric pruning.

The term air pruning is a misnomer, in that root growth is inhibited, rather than pruned—as it is, mechanically, in the open-ground method—by coming into contact with air. This, of course, is the typical plant response, evolved to keep root growth underground.

Similarly, root growth can be inhibited chemically—copper-based coatings are successfully used on the inside of containers.

Proprietary synthetic fabric pots of a weave that allows roots to initially penetrate but subsequently severe, is also in commercial use.

Regardless of the method used, the effect is to inhibit growth of that section of root. The plant, in response, produces new root by branching at a point, or points, further back on that particular lateral.

The Rocket™Pot system developed by Trentcom APS in Victoria, Australia, uses a patented system whereby the constantly curving surfaces of the container direct root growth towards apertures, where air inhibits further growth. The system appears well suited to the landscaping industry, where the higher cost of plants can readily be absorbed.

It is relatively easy to successfully air-inhibit root growth laterally, in that porous-walled containers can be arranged in the nursery with airspace between the individual containers.

It is much more difficult to prevent root growth on the underside of containers. Lack of light, of air circulation and over abundance of moisture encourages unwanted root growth—systems designed to air-inhibit the base of containers are expensive and irrigation needs to be finely managed.

Another concept, inspired by this project, is to use the undercutting technique central to the open-ground method, in concert with the a porous-walled, open-ended container.

So, rather than attempt to prevent root growth beneath the container, the hybrid concept envisages the pragmatic expedient of slicing beneath the ‘pot’, periodically.

While the system would well suit large-scale production, it could be operated on a small scale using a manual ‘peel’, in place of a $100 000 tractor-mounted undercutter.

It is envisaged that the open-ended container would be biodegradable so that it can be planted with the plant.

A particular virtue would be the freedom of the plant to take root wherever it was sat—assuming on ground that was neither extremely hard nor extremely dry, or both—and survive prolonged storage, scheduled or otherwise.

The trademark eNZopen™ has been obtained, with view to keeping the concept in the public domain.

The first stage of developing the system involves establishing a small number of plants in containers fabricated from a porous material—not necessarily biodegradable at that stage—in order to determine whether sound root systems can be produced. This initial work has been included the Täne’s Tree Trust – Lake Taupö Protection Trust open-ground project.

Widely spaced two-year-old eNZopen™ trees, in combination with a large-volume low-cost open-ground filler such as harakeke, might be the closest thing to instant and affordable indigenous forestry, or restoration.

Resilience from day one.


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Part of a hope-based network restoring and enjoying the Mahurangi
 Editor Cimino Cole