The best pH for growing weed in coco coir with Canna Coco nutrients is to keep most of your waterings between 5.7 and 6.0. The max would be 5.5 to 6.5, growing pot in coco outside of that pH range will cause nutrient problems.
Your goal is to keep the coco coir medium at a pH of 5.8 or so which is ideal for proper nutrient absorption by marijuana plants. Varying the pH a bit from 5.7 to 6.0 allows for nutrients that are absorbed best at slightly higher or lower levels than 5.8.
You should always water your coco coir to runoff, aim for 10-20% to drain out the bottom of your container. This ensures the roots get fully saturated and the runoff removes excess nutrient salts that could lead to nutrient burn.
How to fix pH problems in weed plants grown in coco coir
Thankfully it’s pretty easy to fix pH problems in weed plants growing in coco coir. Especially if you catch them early. For the most accurate results, test the pH of the coco’s runoff water to see how things are going inside the root ball.
Too high or too low pH levels will prevent the marijuana roots from being able to absorb necessary nutrients, something known as nutrient lockout. Weed plants suffering from nutrient lockout will show signs of damage, so monitor your plants daily and look for unusual symptoms.
How to lower the pH of coco coir
If your runoff pH is too high or too low, you can fix pH issues easily by flushing the coco coir with properly pH’d water.
For example. if your runoff shows a high pH of over 6.2, try running the next few waterings around 5.6 to 5.7 with about 25-30% runoff and you can bring this down easily. For a pH over 6.5, you’re entering the danger zone and you should flush several gallons per pot plant at 5.6 to make sure to correct the issue more quickly.
How to raise the pH of coco coir
If the pH of your runoff water is too low, say 5.6 or below, you can raise the pH of coco coir in a similar manner by flushing. Flush with water pH’d around 6.3 or so for severe problems and around 6.1 for minor corrections.
Once the runoff pH is back above the 5.7 mark you’re in good shape. Keep an eye on the runoff going forward to try and keep it around 5.8.
The importance of pH meters
A decent pH meter is well worth the investment to determine the best pH for growing weed in coco coir with Canna Coco nutrients. Incorrect pH levels are the biggest cause of pot plant health problems among new weed growers. You’ll need to maintain an accurate pH every time you water. Don’t guess at it.
How to store a pH meter
Make sure to properly store it by adding water to the cap and replacing it over the pH bulb after each use. Never let the bulb of your pH meter dry out, it will stop working.
Recalibrate your pH meter frequently
Every 3 months you should re-calibrate your pH meter according to the instructions they came with to ensure accurate readings.
If you don’t recalibrate your pH meter you will end up giving improperly pH’d water to your weed plants and you’ll end up with nutrient deficiencies. If you identify a deficiency and the readings of your runoff water seem like they should be ok, you may have a recalibration issue.
The best pH for growing weed in coco coir with Canna Coco nutrients is between 5.7 and 6.0. Try to keep the coco coir medium at a pH of 5.8. Alternate the pH of waterings to give a range.
Water to runoff of 10-20%, and monitor the pH of this runoff to catch issues early. Correct issues with too high or too low pH levels in coco coir by flushing your marijuana plants with properly pH’d water.