pH Guide for Cannabis in Coco Coir

Coco Coir is basically said to be a Neutral Grow Medium. But in practical terms, coir materials are slightly acidic in nature; while the normal growing soil also contains minute acidity, the plants are assumed to grow perfectly in a slightly acidic environment. 

The substrate acidity-alkaline is the extreme measures of Hydrogen ions present and is widely known as pH level.

All plants require Nutrients for their growth, and the nutrients intake is subjected to pH level of the nutrient solution/ fertilizers. 

May it be the macro-micro nutrients, once the plant doesn’t have access to the nutrient available, then it will lead to deficiencies and other severe diseases. 

Plants require different pH nutrients at different growth phases. 

Likewise, Cannabis requires ideal pH at the distinct growth zone. The ideal pH for the Cannabis growing in Coco Coir is between 5.8-6.0 in the Vegetation stage (for high absorption of Nitrogen) and the Flowering stage needs 6.0-6.2 (as its essential for Potassium and Phosphorus intake) pH to sustain proper nutrient levels.

But the typical growth pH for Marijuana ranges from 5.5 to 6.2

pH of the medium is calculated either in the feed fertilizers or run off water with the help of pH Meter or pH Measuring Kits.

For a Marijuana plant, pH is always estimated using run-off water. The Run-off Water is excessively washed out water in order to drain away the salt nutrients that may cause harm to plant roots (Nutrient Burn).

pH Maintenance

Make sure about 10-20% of water is run-off to get the utmost optimal level of pH. If you run into lower/higher pH, then adjust it by next watering in bringing back to moderate range. 

Have a practice of measuring the dissolved salts using a ppm meter in order to keep the nutrient composition in check. 

pH Check

As mentioned earlier, pH of Coco Coir is made sure by flushing them using pH’d water (water treated to the level of desired pH) twice or thrice as long as the coir pH is close to target pH. Flush the coir slowly-steadily, to avoid the mishap of nutrient pour out of grow substrate or brush past the root balls of poor density. 

Keep a keen watch over your Cannabis. Any low/high pH level is significantly seen through the unusual symptoms on Marijuana leaves. If there is any high fluctuation in nutrient pH, this will lead to ‘Nutrient Lockout’ in plants that will disable access to nutrients any longer resulting in hindered growth. 

pH Adjust

 If the runoff pH  is too high or too low, then you can fix the pH issue by using suitable ‘pH Buffering Solution’ or the ‘pH’d Water’ that is available on any grow stores.

Generally known as ‘pH Up’ and ‘pH Down’, these are the low dosage solutions used. For every gallon of water, only 1ml of these solutions are required to successfully adjust the pH. Make sure to re-check the pH after injecting the solution. 

The pH adjust solution does not impart any changes in EC of original grow nutrients. 

Alternative Way

Few such alternative ways to adjust the pH level are by using ‘Compost Manure’ like Worm cast, Tea compost and Wood shavings composts. 

These will provide an excellent means of natural, organic and effective solution for pH altercation. The microbial activities around the plant roots will enhance the health and increase resistance towards pests  and pathogens and lower the pH in the long run.  

Another best alternative in driving down the pH is by making use of ‘Citric juice and Vinegar’, just by feeding the plant with water diluted with citric or vinegar solution will make a biggest changes. 

One commonly used method for raising the pH naturally is by adding Limestone in powder or hydrated form. This will also provide an abundant amount of Potassium and Calcium to your grow medium. 

pH Restore

Store the instrument you’re using to measure the pH in a clean, dry place. 

If you’re making use of pH  Meter, then it is best stored with cap-up which is thoroughly cleaned. And don’t let the pH meter dry out in order to avoid malfunctioning. 

Re-calibrate your measuring instrument every 3 months as prescribed in the instruction note, to ensure accurate readings. 


The ulterior purpose of the pH level balance is to keep plants in good health and thrive lustfully. 

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