What is pH Level and Why it's Important for Growing Cannabis

How Can a More Acidic or Alkaline Medium Help Your Autoflower Grow Healthier?
28 April 2020
3 min read
What is pH Level and Why its Important for Growing Cannabis

  • 1. What is ph?
  • 2. How do ph levels affect us?
  • 3. How does ph affect cannabis?
  • 4. In conclusion

Just like providing the optimal growing environment, controlling pH is essential to your plant's nutrient intake. By maintaining the correct pH level and adjusting it for the stage your plant’s in you guarantee a healthy plant and ultimately better quality flowers.

1. What is pH?

PH is a way to measure how acidic or alkaline something is. It has a scale that ranges from 1-14, starting from level 1 "battery acid" and finishing with level 14 "drain cleaner".

Natural water has a neutral pH of 7. Based on this information we can see if a source of water is good or not for human (and plant) consumption.


What is pH Level and Why it's Important for Growing Cannabis: pH scale, how to measure metals and minerals in water

pH scale, how to measure metals and minerals in the water.

A pH level lower than 7 means the water is acidic or “soft”, meaning it has a high amount of metals and can be toxic (like iron, manganese, copper, lead). On the other side, a pH higher than 7 means the water is alkaline or “hard” and has a high amount of minerals (like calcium and magnesium). 


Try to always measure pH levels when moving to a new city or house, this way you ensure the water is good not only for consumption but also for watering your plants.

2. How Do pH Levels Affect Us?   

Consuming excessively acidic or alkaline water is harmful to humans. Even though natural water has a pH of 7, the accepted range is between 6.5-8.5. Within the acceptable range a slightly high or low pH can be unpleasant for several reasons.

Water with a high pH level (alkaline or “hard”) has a slippery feel, tastes salty, and may contribute to a mineral buildup leading to kidney stones.

A low pH level (acidic or “soft”) can have a bitter or metallic taste, it doesn’t present harm to humans unless it has a big concentration of lead. For example, a big concentration of toxic metals can cause poisoning.


Water is considered acceptable for human consumption if it has a pH between 6.5-8.5, that is because on the way to your house it comes in contact with the piping underground and may pick up metals and minerals.

3. How Does pH Affect Cannabis?

The pH level is very important to plant nutrition because it affects nutrient intake. Just like humans, cannabis has a range considered acceptable. The issue with cannabis plants is that they are only able to take up nutrients within a small pH range, between 6-7 in soil and 5.5-6.5 in soilless and hydroponics. These values need to be correct in order for our autoflower to absorb nutrients correctly.


What is pH Level and Why it's Important for Growing Cannabis: pH chart, optimal nutrient absorption in cannabis

pH chart for optimal nutrient absorption in cannabis.

If pH levels are higher or lower then the plant cannot take in nutrients (even if they’re present in the medium) and will start to show signs of nutrient deficiencies.

As you know, all plants require nutrients for healthy growth. They require macro, micronutrients, and minerals, and if plants cannot access these nutrients, it will lead to deficiencies and other health problems.

Tip: If you grow organically pH is not an issue, the microorganisms within will adjust pH and make nutrients more available to the roots. However, growers using inorganic liquid nutrients will have to adjust pH every time they feed.

4. In Conclusion

If you want to grow perfectly healthy plants you should invest in a pH meter. This way you can adjust the pH of the solution you’re feeding your plants. We recommend measuring the pH level of the solution going in and then measuring the runoff going out. This way you can also check the pH level of the medium your plant is growing in.

Sometimes the pH level of the solution is not the same as the medium and this can definitely cause health problems for your autoflowers in the future.

28 April 2020