What is Air Pruning?

Proptek have developed a wide range of air pruning containers and trays that are revolutionizing the propagation industry. But what is air pruning and how can it help you and your plans?

Plants did not evolve to grow in containers and as a consequence of this, roots produced in most containers are very poor. This leads to many problems later in life and is often terminal. There have been a number of techniques developed over the years to improve roots, but none come close to the quality of roots from a Proptek container. The plants grown in our containers have as good a root (if not better!) than in their “natural” way of growing.

The Benefits of Air Root Pruning

Proptek containers use a technique called “Air Pruning” to achieve these fantastic results. The benefits of air pruning are:

  • No chemicals, no toxicity
  • Cheap and affordable – the technique is built into the pot
  • Incredible results
  • Practical: can cover many formats and is easily adapted to any nursery’s needs.

How Air Root Pruning Works

An air pruning container works by having slots or holes in its walls along with a system of ribs or other devices to force the root to grow out of the slot or hole. When the root grows out of the slot into relatively dry air its tip is desiccated or “killed”. Once this first root is air pruned it loses its dominance and many secondary roots develop to replace it. These are then in turn air pruned and again they are replaced by even more roots. Air pruning therefore trains a root system with a very large quantity of young vigorous roots.

The simplest form of this is to simply make roots grow out of the drainage hole in the base of the cell. However, most of our containers have vertical side slots per cell which all air prune the roots up the side of the cell as well as on its base.

This is good as it creates a lot of secondary roots right up the side of the rootball. Great roots right up the rootball mean that after transplanting there are a much larger number of roots that quickly grow outwards giving the plant a great head start.

The Benefits of a Better Rootball

The net result is that the plant will establish more quickly with a higher % survival rate and more uniform growth plant to plant. It is also expected that plants will develop a mature root system earlier and also top growth has been reported to be 20% to 25% greater than for plants in a traditional pot. The reason for this is that if a better root system is developed with a large quantity of younger more vigorous roots which can feed / drink more and support more top growth.

Another benefit of air pruning is improved aeration and drainage via the holes in the container wall. If, for example, you over-irrigate, the excess water drains out so the plant is not sat wet and unhappy as long. The good aeration of our specialist air pruning pots provides a healthy microclimate to ensure plants are as healthy and as strong as possible.

We believe this is the best root system that is available today and is a result of the cell design. There is however one additional thing you must do to get the benefits of ‘air root pruning’. You must raise the tray off the ground so that dryer air can circulate around the outside of the cell to “kill” the emerging root tips.

Other Methods of Root Pruning

There are, however, other methods of pruning roots seen in the industry – all of which are inferior to air root pruning for a variety of reasons:

  • Mechanical pruning such as the trimming of roots on a bare root plant after lifting or shaving of pot grown plants. This is normally a big check to the plant as it is all done at one time and also at the worst time i.e. the transplanting time when the plant is being checked in other ways. It also has the disadvantage of often removing mostly young active roots which are the ones that would be most useful after transplanting.
  • Copper pruning. This is where a copper based chemical is used to coat a growing container which ‘kills’ root tips as they grow close to the copper layer. We believe that this poses health and environmental issues but is also only a short term way of pruning roots as the chemical layer washes off after a year or possibly two. The idea however of copper root pruning is to kill all the older roots, stop root circling and create a large quantity of secondary roots. The root ball on these plants looks a little odd when removed from the container, as there are very few roots visible on the surface as they are killed off as they approach the container surface. Copper treated trays do not have holes so drainage and aeration is not as good as with air pruning tray