Simple Guide to Growing Media Air Porosity and Cannabis Plant Growth Correlation

The critical correlation between the air porosity of growing media and plant growth has been well-documented through scientific experiments and research papers over the years. But what does it mean?

In simplest terms, plant roots need air – oxygen – for respiration.

That means if you’re growing cannabis plants in containers, you need to be 100% certain that there is enough room in those containers for your plants to get the oxygen and water they need without drowning, and preferably, they can get the air and water whenever they need it – not just when you give it to them.

In other words, the air porosity of your growing medium can make a very big difference in the growth of your plants regardless of anything else you do to try to help them along.

Growing Media Pore Space, Water Porosity and Air Porosity

Let’s start with some basic definitions about porosity in the simplest terms possible.

Pore Space

Pore space is the space between all of the solid matter in your growing medium. Solids include things like coir, peat moss, perlite, and so on).

To put the concept into perspective, think of sand compared to gravel. There is a lot less space between particles of fine sand than pieces of gravel. There is even a significant difference between very small pieces of gravel and larger pieces of gravel.

In other words, a growing medium with fine solids has more pores, but they’re much smaller than a growing medium made from coarse solids, which has fewer, larger pores. What matters for your plants’ health is the size and distribution of pores in the growing medium you choose, because those pores have to hold air and water.

And that brings us to the measurement of a growing medium’s ability to hold air and water, which is calculated as total pore space or total porosity. This is the distribution of pores (pore space), and it’s critical to ensure adequate drainage and exchange of oxygen and carbon dioxide. The wrong porosity leads to poor plant growth.

Water Porosity

That leads us to the next concept that growers need to understand about porosity and growing media – the ability of the medium to hold water. As discussed above, the space in a growing medium for roots to develop is filled by solids. When you water your plants, some of the available space is filled with water.

In containerized growing, some of the water drains out (larger pores leads to more drainage) while some is held in the bottom of the container – a result of overwatering that can lead to root problems. The rest of the water is held by the solid matter in the medium, so the plants can access it as needed. Unfortunately, most growing media have limited abilities to hold the water within the solids.

That means the level of available water in most soilless media, like coco blocks, is very low. It’s important to note here that bio365 soilless media is different and has been engineered using patented processes to have exceptional water-holding abilities, so plants can pull water from the media when they need it while maintaining as much aeration (the amount of air around the plant roots) as possible. No other clean, living media does all of that.

Air Porosity

Water and air within the growing media are required for plants to grow, and there is a finite amount of pore space for both when you’re growing plants in containers. Not only is air space critical for plants to get enough oxygen and release carbon dioxide, but it’s also crucial for aeration.

For your cannabis plants to grow to their full potential, there needs to be enough space in the container for maximum root development. Once you subtract the space in the growing medium occupied by solids and water, you’re left with the amount of pore space for air. This is the air porosity of the medium. If air porosity is too low, your cannabis plants’ roots won’t be able to spread out and fully develop.

The key is to use a growing media that has adequate air porosity so you can optimize plant growth and crop yields. If your growing media doesn’t have enough space for air or the solids don’t adequately hold and release water (i.e., the water sits and takes up space), then the air porosity will be limited and lead to poor plant growth. It’s a critical correlation that makes a big difference in your results!

For example, when you use bio365 media, which has exceptional air porosity and water-holding capabilities thanks to our patented engineering processes and technology, you can decrease your container size and use less soil. That leads to savings for you in addition to improved plant growth.

Keep in mind, the air porosity of compressed, dehydrated blocks of coco and compressed peat bales quoted by manufacturers will never be what cultivators get in real-world growing environments. Read more about that problem here: Why You’re Not Getting the Air Porosity You Think in Your Growing Media.

Growing Media Porosity Comparisons

How do popular commercial cannabis growing media compare when it comes to porosity? Let’s take a look!

We’ll start with bio365, and compare it with other media options. As you can see from the charts below, all bio365 growing media contain more than 20% air porosity. Even our blends that include a lot of perlite and have a higher percentage of solids still have 20% or more air porosity.

We can achieve these high levels of air porosity thanks to our proprietary ultimateAIR™ technology, patented BIOCORE® biochar manufacturing process, and additional patented engineering processes.

Compare the percentages for bio365 clean, living media with coir, peat, and compost shown in the charts below. All have less air porosity, which means less room for roots and growth.

Key Takeaways for Cannabis Cultivators

The key takeaway is simple. Growing media has a defined amount of pore space that is used by plants to access water and air. Combined with the ability of the medium’s solids to hold water, the porosity breakdown is critical to plant growth.

Higher air porosity in your growing media should be a top priority for you, but understand that most growing media used by cannabis cultivators have just two levels of pore space – macro-pores and micro-pores. However, all bio365 growing media have macro-pores, micro-pores, and nano-pores. This third level of pore space is part of our patented biochar technology that opens a microscopic level of pores for your cannabis plants. As a result, your plants can consistently access more air and develop bigger and better root structures.

Take a look at the chart below to see how the air porosity of some of bio365’s growing media products compares to other similar options.

For a comparison of bio365’s clean, living media to inert soil, take a look at the chart below.

Every percentage point counts when it comes to root growth and plant health, which correspond directly to your plant growth and yields! Contact us to learn more about porosity and how bio365 soil can help you get better results.