What should be the pH in cannabis cultivation?
   01/22/2025 23:49:14     Poradniki
What should be the pH in cannabis cultivation?

The Impact of pH on Cannabis Plants



How pH Affects Nutrient Availability


The pH level of the soil plays a crucial role in the ability of cannabis plants to absorb nutrients. This is because different pH values influence the solubility of nutrients.

At a pH of around 6.5, most nutrients become water-soluble ions, which plant roots can easily absorb. This provides optimal conditions for plant growth and development.

However, when the pH level drops below or rises above the optimal range, nutrient availability changes.

For example, low pH levels can increase the availability of iron (Fe), manganese (Mn), and aluminum (Al), which in excess can lead to toxicity.

On the other hand, high pH levels limit the availability of phosphorus (P), potassium (K), sulfur (S), boron (B), and molybdenum (Mo), potentially causing deficiencies and stunted plant growth.

Below is a diagram illustrating the uptake of micro and macronutrients.


Benefits of Maintaining Optimal pH


Maintaining the correct pH level in the soil offers numerous benefits. Plants grow better, are more resistant to stress, and produce larger, higher-quality yields. Additionally, maintaining proper pH ensures efficient use of nutrients, maximizing the return on fertilizer investments.

Regular monitoring of soil pH helps detect early signs of issues, such as nutrient imbalances. This allows for prompt corrective actions, minimizing risks during later stages of cultivation.


Signs of pH Issues in Cannabis Cultivation


Below are common symptoms of incorrect pH levels in cannabis cultivation:

What Are the Signs of Low pH in Cannabis Cultivation?

  • Stunted plant growth.
  • Red or purple discoloration on leaves and stems.
  • Leaf death, visible as brown spots and wilting.
  • Burnt leaf tips.
  • Leaf curling.
  • Yellowing leaves with green veins (chlorosis).

What Are the Signs of High pH in Cannabis Cultivation?

  • Brown spots on leaves.
  • Deformed or wilted leaves.
  • Death of new leaf tips.
  • Yellowing leaves with green veins.
  • Dark green leaves with red or purple hues.

How to Solve pH Issues in Cannabis Cultivation?

All the above symptoms are caused by nutrient deficiencies, often resulting from pH imbalances. These problems cannot be resolved simply by adding more fertilizer. The pH level must first be corrected by flushing the soil and then applying a balanced nutrient mix.

Nutrient Lockout


Nutrient lockout occurs when plant roots cannot absorb available nutrients. This issue is often caused by incorrect pH levels but can also result from the accumulation of mineral salts near the roots due to intensive fertilization. To prevent lockout, regularly flush the soil and monitor its pH levels.


Best pH Levels During Flowering Phase


During the flowering phase of cannabis plants, it is beneficial to slightly raise the soil pH to a range of 6.5–7.5. This supports better absorption of phosphorus and potassium – key nutrients that promote flower development. At the same time, nitrogen availability is reduced, preventing unwanted vegetative growth during flowering.

Maintaining the appropriate temperature is also important during this phase. The optimal temperature for vegetation is 22–25°C, while during flowering, a range of 21–23°C is recommended.


How to Monitor and Adjust pH


Regular monitoring of water and soil pH is crucial for healthy plant growth. You can use digital pH meters or drop testing kits for measurements. To lower pH, use solutions containing phosphoric acid, and to raise it, apply dolomitic lime. It is important to make adjustments gradually to avoid plant shock.


Measuring pH Levels Using Drops
Testing pH with a drop kit is a simple and effective process:

  1. Collect a sample of water or nutrient solution.
  2. Add a few drops of the pH indicator to the sample.
  3. Compare the resulting color to the color chart provided with the kit.
  4. Adjust the pH if necessary using appropriate solutions.


Measuring pH Using a Digital Meter

Digital pH meters are more precise and easy to use. After calibration, simply immerse the meter's electrode in the sample to obtain an accurate reading. Regular cleaning and calibration of the device ensure reliable results. Below are examples of high-quality meters, such as Aqua Master and BlueLab.


Conclusion


pH control is one of the most important aspects of successful cannabis cultivation. Regular monitoring, pH adjustments, and the use of appropriate tools and techniques ensure healthy and abundant yields. If you have questions or issues related to pH, it is advisable to consult experienced growers or use advanced measurement equipment.