Tweet

Proper pH levels for medical marijuana are usually considered to be between 5.2 and 5.9.
(Click to enlarge)

 Medical marijuana plants like a slightly lower pH level for optimum growth. 

What Is pH?

This is a question that usually makes new growers scratch their heads and reach for the pipe. pH applies to the level of alkalinity or acidity of a given “thing,” in this case, the nutrient solution you’re using to grow your joy. The pH scale starts at 0 and rises to 14. A value of 7.0 is considered neutral, with values over 7.0 being alkaline and values below 7.0 being acidic. Now, you might be asking yourself why this is important. If you were a chemist, you’d know already. Since you’re not, here’s why.

The nutrient solution you’re using is basically a cocktail of various chemicals. These chemicals can react to each other in a process called covalent bonding and form new chemicals that you don’t want. You don’t want these new chemicals because your plant can’t use them. This process of covalent bonding is largely dependent on the pH of the solution the chemicals are suspended in—in this case water.

What pH Is Perfect For Medical Marijuana?

With the chemicals being used in your average hydroponic solution, a chemist would say that the optimum pH would be 7.0, which is neutral. The reasoning behind this is that in keeping the solution neutral, covalent bonding of the constituent parts of your solution will be kept to a minimum. But since your medical marijuana plants like a slightly lower pH level for optimum growth, you have to cater to your babies and take the slight loss of nutrient value. Fast growing leafy plants like MMJ generally like a lower pH in the range of 5.2 to 5.9.

Fortunately, a lower pH will bond fewer nutrients of the type in your solution than will a higher pH. If you let the pH value go beyond the optimum range of 5.2 to 5.9, you’re opening yourself up to undesirable levels of nutritional deficiency and toxicity, both of which can seriously impede your growth. Be vigilant.

How Grow Mediums Affect pH.

In your research of the various hydroponic methods in use, you might have realized that most of the growing media in use is relatively inert (rockwool, pea gravel, sand, etc.). That is, the growing medium won’t react with the nutrients in the solution. For those methods that use inert media, a pH of 5.2 is recommended for optimal elemental uptake. It is at this pH level that the roots will assimilate the nutrients in your solution most efficiently. If the root has to work less to assimilate the required nutrients, the rest of the plant will benefit.

At this point, those old-hand stoners that have been growing since the '60s will shake their heads and tsk-tsk you. They will swear by a neutral pH of 7.0 for the nutrient solution (if they check the pH at all). New research has shown that this lower pH value is the optimum for green leafy plants that grow this quickly. My own experiments with this lower pH have convinced me – the buds were plentiful and fat, and the shake made couch-glue hash oil that was to die for.

Most hydroponic medical marijuana growers spend a lot of time and energy adjusting their pH levels, but new technology is making it easier than ever to get the proper pH.