Home Cultivation Air Root Pruning for Cannabis Plants

Air Root Pruning for Cannabis Plants

Boost Yields by Up to 30% by Changing Your Pots

PHOTO: Courtesy of windowsillweed.com

You may have a beautiful greenhouse or grow room setup, but if your pots aren’t right you could be limiting your potential yields right off the bat. This article will introduce you to the concept of air root pruning and gives a compelling argument as to why you should consider changing to aerated pots.

The roots are the veins of life that feed a plant the water and nutrients it needs to grow and flourish. Up top, the leaves of the plant breathe in carbon dioxide, down below the roots breathe oxygen. Not too much oxygen though, or the roots will “burn” through dehydration. This burning actually gently prunes the roots as they come into contact with a drier, oxygen-rich area.

Imagine in nature a cannabis plant growing on the edge of a bank, you would not expect the roots to poke out the lower side of the bank to be of equal size to those growing into the hill. This self-pruning is nature’s clever little trick to keep roots where they should be to find food in the ground.

In the grand scale of evolution, artificial pots are a relatively new phenomenon. They were first used by the ancient horticultural masters the Egyptians. Although this was several thousand years ago, it is nothing compared to the existence of plants, who have been on this earth for 700 million years.

The trouble with regular pots

Here’s the trouble with pots. A plant doesn’t know it’s in a pot. It feels where it is by sending out the roots that search for food. When a root hits an obstacle, it tries to find an alternative route. A new root route. If a root hits a large stone, you would expect it to go round it. You could say it does a Roots Manuva. When it hits the edge of a pot it tries to do the same thing. It has no way of knowing that the pot actually wraps 360 degrees around the plant. So it sets off to go around the obstacle, not knowing that the obstacle actually goes around it.

This means that precious growing energy is spent sending the roots around in circles in the same area of a pot using up all nutrients in this region in the process. The plant has become bound in it’s own roots which, unfortunately in this case, are programmed to go outwards. On their quest for an escape that does not exist they miss all the nutrients sitting inside the bulk of the pot. Going in circles around the pot does not result in air pruning of the roots as the pot keeps the growing medium from becoming drenched in air.

New root shoot routes

If the pot allowed the air to pass through, the roots would self prune as they come in contact with the surrounding air. It stops growing and sends a signal back to base to get the backup of more root shoots. As these roots grow through new patches of undiscovered nutrients, the plant is fed in a much more efficient way.

Energy saved from sending roots around in circles can be spent up top on making more leaves, which give the plant more light, which in turn provides more fuel to convert the nutrients being fed through the roots to building more plant matter.

Nutes for root shoots

Come flowering time, the fine roots are evenly spread throughout the nutrient rich growing medium.

The creation of many fine roots is an important factor. More fine roots have a greater surface area than a few fat roots. That’s why they say big fat fries are actually healthier than finely cut french fries. The reason is the greater surface areas of the many fine fries takes in more cooking fats. In our case the many fine roots take in more nutrients.

These many fine roots efficiently provide the plant with the nutrients it needs to build a strong fibrous framework to support heavy flowering buds in the form of the stem and branches. The extra air and less stagnant water allow healthy bacterias to thrive, which also help the roots take in more nutrients.

This is all great, but how can it help us humble cannabis caretakers? It just so happens that there are a few manufacturers that produce breathing aerated pots.

Smart Pots

Smart pots are the original fabric pots and have been on the market since 1984. They are used extensively by horticultural specialists throughout the world. The safe, non-toxic, durable fabric can be recycled up to ten times using your washing machine. It is reported that yields can increase up to 30% compared to regular pots of the same size. Smart Pots come in many sizes from 1 gallon to 100 gallons and a 10 pack of five gallon (20 litres) pots will cost you around $50. The larger pots come without handles, but when you fill your pot you turn over the sides, like turn ups on your pants which give you a firm hold when having to move pots around. Depending on your growing needs, they can also offer custom sized solutions.


Air-Pots market themselves as a “root enhancement system”. Instead of a semi permeable fabric, it is made from recycled plastic and its many spikes each contain a small hole to allow air to enter the growing medium. They should last for years as long as you don’t bash them about. The current pots are now in their sixth generation. They are used by expert horticulturalists and nurseries throughout the world, including the prestigious Kew Gardens in London. They can be bought in sizes from 1 litre to 54 litres. A pack of 10 x 22 litre pots (5.8 gallons) will set you back around 100 bucks.

Which one to choose?

In essence, both solutions achieve the same thing. Smart Pots are relatively inexpensive compared to Air-Pots, but have a limited life span. Up front costs for Air-Pots are about double, but the pots will last longer. My advice would be to go for the cheaper Smart Pots and when you have worn them out, decide if the additional cost is worth your while, or you may find you need to select a different size.

It would be very interesting to run them under the same lights using clones to see if there is a noticeable difference in yields.

Which size is best?

When it comes to growing cannabis, you should select the largest pot that you can to fit in your garden. The larger the pot, the more nutrient rich growing medium you can use and the more space for the roots to form. More roots and more nutrients mean that the resulting plant will be stronger, bigger, and yield more. It may be that the pots are too big and the resulting plants are unmanageable. A reduction in size the following year could help you to find a balance.

There are other manufacturers out there that offer their own take on the same principles, but be wary of cheap imitations that don’t have the brand name to uphold. You don’t know that the materials they are using are safe for human consumption and they may well just break under everyday use.

Do you use aerated pots? Did you find an increase in yields? Please share your thoughts in the comments below.


  1. For outdoor growing, till/prepare plots.
    Make a 6-8ft ring of bamboo stakes in the ground.
    Cut a section of chicken wire lengthwise to give you 2 long sections roughly 1ft tall.
    Run the wire around the inside of the stake ring, with the pointy side down.
    Line the inside of the wire mesh with a healthy layer of straw.
    Back-fill with dirt.
    Add a layer of coco, and 1-2″ of perlite as a top coat to your new pots.
    You will end up with a large, perfectly shaped pots that breathe and retain moisture.

  2. My problem with smart pots is they hold to much water right at the bottom,an sour an hurt the plants. The sides do air well but there to much fabric at the bottoms to dry well enough,an this was with a very strick watering schedule,same schedule as my other pots with holes in the bottom an cuts in the side of the pots. ( No smarts pots for me). !!!!!!!!!!¡!