In Understanding Soil pH: A Beginner’s Guide, we talked briefly about what pH is and how it relates to cannabis. This time, we’re digging deeper! In this article, we’ll look at the importance of pH for cannabis growers and introduce environmental factors into the equation. 

Maintaining the optimal pH for your plants may seem complicated, but it doesn’t have to be. BlueSky Organics has quick and easy solutions to help you balance your soil and let your plants thrive. Let’s dive into why pH is important.

What is pH?

As covered in our beginner’s guide, pH is a measurement of how acidic or basic a solution is. pH stands for potential of hydrogen. Confusingly, a greater potential of hydrogen (more hydrogen ions available) corresponds with a lower pH. Before we dive into the concept of soil pH, let’s look at what makes a solution acidic or basic.

The word H2O written in water droplets on glass
Each water molecule, H2O, is made up of one positively-charged hydrogen ion and one negatively-charged hydroxide ion. The charges balance, giving pure water has a neutral pH.

An acidic solution has many hydrogen (H+) ions and a basic solution has many hydroxide (OH) ions. A solution that is balanced in these ions is considered neutral.

One hydrogen ion combined with one hydroxide ion produces H2O, which you may recognize as the chemical formula for water. Pure water lands in the midpoint of the pH scale and is considered a neutral solution.

A pH scale is logarithmic. It has 14 points, each representing a tenfold increase in basicity. A solution with a pH of 4 has 100 times more hydrogen ions than a pH of 6. 


Understanding Soil pH

Cells in the human body have a relatively neutral pH of around 7.4, as do most living things.
Just as we don’t worry about maintaining the pH inside our own bodies, the internal cellular pH of our plants is not a concern. The pH of the soil environment, however, is a top priority.

To better understand soil pH, it can be helpful to think of soil as a liquid. Many of the nutrients in soil are water-soluble and dissolve into the soil. This helps to keep the nutrients mobile and gives the soil an overall pH.

The soil pH is determined by the chemical compounds in the soil, whether they are acidic or basic. Common acid-forming molecules in soil are hydrogen, aluminum, and iron. Common base-forming molecules are calcium, magnesium, potassium, and sodium. Sound familiar? These are some of the key macronutrients and micronutrients required for plants to grow. We’ll come back to this later.


Factors Affecting Soil pH

Acidic and basic soil can come from four different sources:

  1. Parent Material

four different types of rocks, highlighting the importance of parent rock material in determining soil pH for cannabis growers
Soil is formed from the breakdown of rock. The type of rock, or parent material, has an effect on the pH of the resulting soil.

Parent material refers to the type of rock from which the soil was originally made. Soils developed from basalt or limestone are more basic, while granite or shale-derived soils tend to be acidic

Basic soils with a pH higher than 6.5 are known as alkaline soils. Alkaline soils absorb water very poorly, making them very difficult to grow with. Rice is an exception and can be successfully grown in alkaline conditions.

  1. Organic Material

In our recent composting article, we followed how organic materials are broken down by microorganisms into valuable nutrients. These nutrients, as mentioned above, are also acid and base-forming molecules. When organic material is broken down, these molecules are released and change the soil pH. 

  1. Man-Made Products

Soil pH can also be changed through the use of manmade non-organic fertilizers. Nitrate-based fertilizers increase soil pH, while ammonium-based fertilizers lower pH

Non-organic fertilizers often come with instructions to apply a balancing agent. This helps to counteract the pH altering fertilizer. For example, acidifying ammonium fertilizers require the application of lime, which is basic, to ensure that soil pH doesn’t shift drastically. 

A simple way to avoid this balancing act is to grow organically. Organic fertilizers contain nutrients that are slowly broken down to help maintain a balanced soil environment.

  1. Leaching

River winding through agricultural lands, highlighting nutrients leaching in soil
Many nutrients are water-soluble and will move out of the soil surrounding plant roots. This nutrient runoff can end up in water sources surrounding agricultural land.

Leaching is the loss of nutrients and minerals from the soil surrounding plant roots. Excessive application of water can cause leaching and shift the soil pH into non-optimal ranges.

Soil pH is constantly changing due to environmental factors. To make sure that pH fluctuations are within a healthy range, we must regularly monitor a soil’s pH. Thankfully, monitoring soil pH is quite straightforward.


pH for Cannabis Growers

Cannabis plants can only thrive with the right nutrients, in the right amount and at the right time. In our articles on macronutrients and micronutrients, we discuss what the right nutrients and right amounts are. These factors are crucial in preventing nutrient lockout. 

Nutrient Lockout

Nutrient lockout refers to soil conditions preventing certain nutrients from being taken up by the plant. One example is having excessive nitrogen in the soil, which prevents calcium from being absorbed. This can lead to symptoms of a calcium-deficiency, even when there is plenty of calcium present in the soil. 

Apart from one nutrient overwhelming the plant’s ability to take up another, pH can affect the capacity for soil to hold onto nutrients. The size and charge of a nutrient molecule affect whether that nutrient can be easily displaced from the soil and washed away. 

Strong Attractions

Cannabis plant closeup highlighting organic growing and pH for cannabis growers
Organic growing focuses on the whole plant-soil ecosystem. In organic farming, healthy microbial and fungal communities in the soil are a top priority.

In chemistry, negative and positive charges attract each other and similar charges repel. At a high pH (where the soil has many negative hydroxide ions), positively charged nutrients can easily stick to the soil. This strong binding makes it more difficult for plants to draw up nutrients, resulting in poor soil for growing. 

Conversely, at too low a pH, nutrients won’t stick and can easily be washed away. This can lead to imbalances and levels of nutrients that are toxic or deficient. For this reason, most plants prefer a moderate, relatively neutral pH. 

Depending on the plant’s nutritional demands, slightly acidic or slightly basic conditions may be preferred. Nutritional demands also change based on the stage of growth that a plant is in. For a grower, knowing the preferred conditions for your crops during these stages is essential for optimal plant growth.


Organic Growing & pH

Beneficial microbes and fungi are key factors in sustainable success. Organic fertilizers are non-burning, adding nutrients to the soil that can be slowly broken down by microbes. This ensures that the plants aren’t shocked or “burned” by rapid changes in their environment. 

Perhaps unsurprisingly, beneficial microorganisms also have preferred pH ranges. Researchers from North Carolina State University recommend a pH of 5.8 to 6.2. This range satisfies the microbes in soil, while providing a balanced nutrient profile for optimal growth.


What BlueSky Organics Can Offer

BlueSky Organics products pH UP and pH down, used for managing pH for cannabis growers
pH UP and pH DOWN are natural pH adjusters that make it easy to manage soil pH, while protecting beneficial microbes in the soil.

Managing pH fluctuations is quick and easy with BlueSky’s pH adjuster productspH UP and pH DOWN. Maintaining your soil pH in that sweet spot can be too!

Organic growing produces hardier, drought and disease-resistant plants. It also produces cannabis of higher quality and yield, in a process that is environmentally-friendly. What more could a grower ask for? Follow your Custom Grow Calendar for proven cannabis growing success.