What’s pH? Understanding and Measuring pH in Your Grow Room

What’s pH? This is a question that usually makes new growers scratch their
heads and reach for the pipe. The term pH refers to the level of alkalinity
or acidity of a liquid substance. 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. The liquid is the nutrient solution
being used to grow a healthy cannabis plant.

The nutrient solution 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 the plant can’t effectively use. This process of
covalent bonding is largely dependent on the pH of the solution the
chemicals are suspended in, in this case water. With the chemicals being
used in the average hydroponic solution, a chemist would say that the
optimum pH would be 7.0, which is neutral. In keeping the solution neutral,
covalent bonding of the constituent parts of the solution will be kept to a
minimum.

However, since cannabis plants like a different pH level for optimum
growth, it’s okay to lower the pH and take the slight loss of nutrient
value. Fast growing, leafy plants generally like a lower pH in the range of
5.2 to 5.9. Fortunately, a lower pH will bond fewer nutrients than a higher
pH will. If the pH value goes beyond the optimum range of 5.2 to 5.9,
undesirable levels of nutritional deficiency and toxicity will occur, both
of which can seriously impede plant growth. Be vigilant.

In researching the various hydroponic methods in use, most of the growing
media like rockwool, pea gravel and sand is relatively inert. That means
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 the solution most efficiently. If the root has to work less to
assimilate the required nutrients, the rest of the plant will benefit.
*Measuring and Adjusting pH*

Measuring pH is relatively easy and there are quite a few choices in terms
of methods. The most inexpensive and low-tech method for measuring just
requires purchasing a pH kit and taking a sample from the nutrient
solution. After following the directions, use the color chart to determine
the pH of the solution.

This low-tech solution poses some obvious limitations, not the least of
which is the difficulty in deciding which color is closest if you’ve been
into the fruits of your previous harvest. The kits typically sell for $5 to
$10.

If the pH isn’t the appropriate level for your plant, knowing what chemical
to add to the nutrient solution and when is paramount to success as a
grower. When the pH level is alkaline, meaning the pH level is above seven,
it can be lowered with saltpeter, sulfuric acid or phosphorous. When the
pH value is too low, it can be raised with calcium carbonate, lime or
potash. Most fertilizers cause a pH change in the nutrient solution. Adding
fertilizer to the nutrient solution almost always results in a more acidic
pH, so adjust accordingly.
*Proper Handling*

Handling all of these chemicals safely is important. As a general rule,
never use metal. Instead opt for glass or plastic or the nutrients will
react with the elements in the metal and mess up the nutrient ratios. Never
add the acid to the vat of nutrient. Fill a small glass container with the
nutrient to be balanced and add a few drops of the necessary chemical. Stir
it in well and add small amounts at a time to the large vat of nutrient
until the proper pH balance is achieved.

As time goes on, the amount of salts produced by the breakdown of
fertilizers in the medium causes it to become increasingly acidic.
Eventually, the concentration of these salts in the medium will stunt the
plant and cause browning out of the foliage. As the plant gets older, its
roots become less effective in bringing food to the leaves. To avoid the
accumulation of these salts in the medium and to ensure that the plant is
getting all of the food it needs, be sure to flush the system with clean,
pH-balanced water every couple of weeks. Do this in lieu of that cycle’s
feeding.

There’s always been a big debate over when to adjust your pH – before and
after you add nutrients to the water, or just after. The truth is, growers
can do both. The reasoning for doing both is that water is rarely dead on
neutral. It’s either acidic or alkaline, depending on the region. Render
the water neutral first by bringing it to a pH of 7.0. Then add the
nutrients to that chemically-neutral solution and adjust to the desired
range within 5.2 to 5.9 pH.

Because there are so many factors that go into the delicate art of
cultivating cannabis, learning how to properly measure and adjust the pH
balance on nutrient solutions will have a clear effect on the appearance,
potency and health of cannabis plants. Practicing and perfecting this step
will be what makes a grower’s crop stand out from the crowd.

*TELL US*, have you taken pH into consideration when growing cannabis
plants?

The post What’s pH? Understanding and Measuring pH in Your Grow Room
appeared first on Cannabis Now.