Soil pH for Cannabis

Measuring the soil pH for cannabis plants is essential. The pH level impacts your plants’ ability to grow into healthy, potent, budding yields.

Balancing pH ensures nutrient solubility and uptake for these plants. This is why it’s crucial to measure and monitor pH levels to guarantee your fertigation strategy isn’t limiting your plants’ potential.

But what should the soil pH for marijuana plants look like? And what’s involved here?

In this post, we answer all of your questions about soil pH for cannabis grow operations.

soil pH for cannabis plants to grow to their full potential like the nice green buds in this picture

What is the Soil pH for Cannabis?

The pH scale ranges from zero to 14.0. Through this scale, it’s possible to see how chemical compounds will interact with each other in accordance with their iconic state.

Keep in mind, pH shows the concentration of hydrogen ions in a solution. But it’s easier to understand this scale when you know that acids are at one end and alkaline bases are at the other.

Values less than 7.0 show acidity. On the other hand, values beyond 7.0 indicate alkalinity. Deionized water is neutral with a pH of 7.0.

Small changes in this scale are significant for plants. For instance, a pH level of 4.0 is ten times as acidic as a solution boasting a pH level of 5.0. When it comes to growing cannabis plants, this has a major impact on the form of nutrients found in the growing medium.

If the pH is low, some micronutrients like manganese and iron become more soluble. This means the plants have more access to these micronutrients, which can result in toxicity. However, if the pH increases, some micronutrients and phosphorous are less soluble, meaning plants have less access to these key nutrients.

What’s the pH Level for Cannabis Plants?

Nutrient availability increases or decreases with the pH a plant is subjected to. However, for cannabis plants, it’s best to have a pH level between 5.8 to 6.2.

The concentrations of your nutrient solution don’t necessarily matter when it comes to unbalanced pH levels. This can produce an inhospitable environment for nutrients, and if these nutrients aren’t adequately available to your plants, they don’t thrive.

Many plants, cannabis included, prefer soil conditions that are slightly acidic. But they’re tolerable, allowing a wide range without experiencing symptoms like inter-veinal chlorosis or bronzing.

As long as the plants have substrate within the pH of 5.0 to 7.0, they’ll do fine. But it’s important to remember that pH levels exceeding 6.2 or less than 5.8 will limit plant growth.

Keeping optimal pH levels requires growers to test pH levels once every two days, adjusting as needed. This is something that can be done using a digital meter.

Soil pH for Cannabis FAQ

Does pH matter for cannabis?

Yes. Since pH levels impact nutrient solubility and uptake of plant nutrients, pH should be monitored closely. Simply put, to keep your plants thriving, it’s best to have the substrate pH between 5.0 and 7.0.

How important is pH to cannabis?

Cannabis can be quite demanding when it comes to pH, and without the right pH levels, nutrient availability can rise or fall. If the nutrient availability increases, you risk toxicity. And with nutrient availability decreases, your plants face deficiency. In both scenarios, your plants will not grow to their full potential, if at all.

Do I need to pH my water when growing in soil?

As long as you’re using fresh deionized water, you don’t need to pH your water. You’ll already know that the water you’re using is 7.0. For those who grow cannabis in soil, the best pH level for your root zone is between 6.0 and 7.0. With this in mind, you will not risk damaging your plants if you’re using deionized water.

What pH should runoff water be?

Most of the time, the pH of your runoff water will be around 6.2 if you’re using soil and 5.8 if you’re using a hydroponic grow setup. For your first couple of feedings, your runoff will be within 1 pH of these numbers, and within a few weeks, you’ll see it shift more towards the precise numbers you’d expect.

Concluding on Soil pH for Cannabis

The soil pH for cannabis grow operations is essential to track. If you find your substrate exceeds or is less than the numbers explained in this post, it’s best to adjust accordingly. This will make a significant difference in the overall health of your plants, and result in better, more potent yields.

Louis Levey is the Content Success Manager and Founder at No Strings Content. He's passionate about helping cannabis businesses use content to attract, educate, and convert audiences. His hometown is Boca Raton, Florida, but he currently lives and works remotely in Chiang Mai, Thailand.

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