Soil pH 101: How to Properly Grow Cannabis

Maintaining Soil’s pH Levels for Healthy Cannabis Growth


When it comes to agriculture, understanding soil pH is crucial, which applies to growing healthy cannabis plants as well. However, it can be challenging to know where to start, especially if you’re just getting started. Luckily, there’s ample information out there to get you started. 

Importance of pH Levels in Cannabis Growing: 

When deliberating the best soil pH for cannabis, consider the optimal level for a plant to absorb nutrients. pH levels are measured on a 1-14 scale, with seven being neutral (think: pure water). Acidic substances have a pH lower than 7 (vinegar or lemon), and anything with a pH level higher than 7 is alkaline (ammonia or bleach). Any plant in soil with a pH level that is too low or too high will experience a “nutrient lockout,” which means it cannot absorb nutrients from the dirt. 

Optimal pH Level for Cannabis Growing: 

For optimal cannabis growth, the soil needs to be slightly acidic or neutral, ranging from about 6-7 on the pH scale. If it’s any higher or lower than that, the cannabis plant cannot absorb nutrients and will fail to grow to its full potential. 

Maintaining pH Levels in Cannabis Soil: 

Knowing the best cannabis soil pH levels and maintaining them are two completely different tasks. The easiest way to maintain a soil’s pH levels is to test the soil. You can do this in several ways. First, you’d want to take a small, debris-less soil sample and mix it with distilled water. From there, pour vinegar in to see if it bubbles or fizzes. If it does, your water is alkaline, and you may have to consider how to lower the pH in cannabis soil. You can do so by adding a pH-lowering solution, such as sulfur. If it doesn’t bubble, take another sample, mix distilled water into it, and then add baking soda. If the solution creates a reaction, your soil is acidic, and you can raise the levels by adding limestone or another pH-raising solution. The best way to get accurate results is to mix distilled water into a soil sample, filter the soil out with a coffee filter, and test the remaining water with a pH test strip. This process will get the most accurate result, and you can add a pH-lowering or -raising solution to the water to get the ideal level. 

Essential Nutrient Levels for Cannabis Growth: 

Just as humans do, cannabis requires different levels of nutrients for various growth periods. In the growing phase, cannabis plants require a nutrient blend high in Nitrogen (N), medium in Phosphorus (P), and high in potassium. In the flowering phase, they demand a mix that’s low in Nitrogen (N), medium to high in Phosphorus (P), and high in Potassium (K). This change is because a mix high in Nitrogen can discourage bud development. If the cannabis soil pH is too low or too high, the nutrients will get trapped in the soil. You can purchase cannabis nutrient kits or mixes to add to your dirt. 

Introduction to UV Sterilizers for Watering Systems: 

When maintaining the perfect environment for cannabis growth, a prospective or seasoned grower should consider the cannabis soil pH levels, the system providing water to the plants, and the possibility of unwanted bacteria. Installing UV sterilizers for a plant’s watering system can ensure water cleanliness, preventing infection in cannabis plants. UV sterilizers do just that: sterilize water using the power of UV. Doing so helps ensure that foreign bacteria and algae do not alter the pH levels of your soil, allowing your cannabis plants to grow to their full potential. 


 One of the best solutions to maintaining proper cannabis soil pH levels is to install a UV sterilizer on your water system. This way, you can rest assured that your soil’s pH levels won’t fluctuate from outside sources, so you don’t have to test pH levels as often. Instead, your water will remain untainted by unwanted bacteria and will absorb only the purest water, ensuring healthy cannabis growth. 

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For over three decades, Aqua Ultraviolet has been the premier manufacturer of ultraviolet sterilizers and bio-mechanical filtration.

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