How to Measure pH in Cannabis Growing?

The pH value of the growing medium and nutrient mixtures in water are some of the main factors to consider in the day-to-day running of any grow, especially if using advanced techniques such as hydroponics or aeroponics in cannabis cultivation.

If we want our self-grow to be successful, we must look after factors such as humidity, temperature or light intensity. However, it is the pH of the irrigation solution that can block nutrient absorption and therefore ruin a crop.

pH is used to measure the acidity of a substance, whether liquid or dissolved solid. Its range of variation is between 0.0 and 14.0. If it has a pH below 7.0, the solution is considered acidic, whereas if the pH is above 7.0, it is considered an alkaline solution. Those substances that hover around a pH level of 7.0 are those considered neutral pH. In growing, a neutral pH value is considered between 5.8 and 6.5, which are the ranges in which the plant has the highest level of absorption:

Due to its importance, the pH meter for growing is part of the wide range of growing accessories we offer at Growlobby.

Is it important to measure pH in cannabis growing?

The pH level directly influences how our plants absorb and assimilate their nutrients. Therefore, we must consider pH as an important element when ensuring that we have healthy plants with proper nutrition. If pH levels are not maintained stable, different minerals accumulate in the growing medium that can create a toxic environment for the roots, which will cause plants to be unable to absorb nutrients and deficiencies will appear that can become a serious problem. To avoid any type of problem, we recommend you have a Hanna pH and EC meter.

In situations where the pH of the water used is more alkaline or acidic, the necessary elements for plant nutrition, such as nitrogen, phosphorus or potassium amongst others, become less soluble and therefore it is harder for the plant to absorb them.

The pH does not have to be at the same level all the time, as depending on the variety, the growing medium, the type of growing (organic or mineral) and what point in the growing cycle you are at (germination, growth, pre-flowering, etc.) it should have certain values. We can grow at levels between 5.8 and 7.0 pH, but it is easier to work with average pH levels than to make a mistake and create a lockout at a particular moment.

In hydroponic, aeroponic or inert media grows:

• First weeks: 5.8 – 5.9
• Growth: 6.0 – 6.2
• Flowering: 6.0 – 6.3

In peat or soil mix grows:

• First weeks: 5.5 – 7.0
• Growth: 5.8 – 6.5
• Flowering: 6.0 – 6.5

How to measure soil pH

We must take into account that pH varies if we water only with water or if we add products that might alter it. The correct way to measure substrate pH is either with a soil pH meter or by using a simple and economical method with which you will only need a pH meter and follow the instructions of the following technique (1:1):

1. Have a pH meter properly calibrated on hand, as well as three containers, a clean cloth, substrate and distilled water.
2. Choose the smallest container and pour in one measure of distilled water, pour it into another of the containers.
3. Add one measure of substrate to the same container and press it down using another container until you reach the water measurement from the previous step with the substrate completely compressed.
4. Mix substrate and water in the second container until they are well combined.
5. Filter the solution into a third container using the clean cloth.
6. Once filtered, measure the pH of the resulting water.

How to measure water pH in cannabis self-growing

Once we have added the fertiliser, substrates and additives, we must measure and correct the pH. Therefore, there are numerous devices capable of measuring pH, some more complex will also tell us other levels, such as pH measurements, EC and temperature. For EC, you can use an Hanna EC meter which you can find on our website. 

pH for cannabis is easy to control with the right equipment, with meters from brands like Hanna or Bluelab you ensure precision and quality. You can now purchase them on our website and physical shop.

When should I start measuring pH?

The answer to this question is very simple: it is necessary to measure these parameters always, that is, after germination we must take them into account at all times so that our plants can properly absorb nutrients and the plants can grow without deficiencies. It is usually measured in the water already mixed with fertiliser, that is, we do not usually measure it in the base water unless we are only going to water with water.

How to measure cultivation water pH?

We can measure water pH with various types of pH meters. The most well-known is the drops type, as they are perfect for outdoor plantations, cheap and easy to use.

1. To measure pH with cannabis reagent, simply take water from the irrigation well mixed, with its respective fertilisers and additives already dissolved.
2. A sample of the water is taken in the tube and we add a couple of drops of the reagent, we stir it and so we can know the initial pH we are starting with by comparing it with the colour on the chart.
3. Normally, at the first measurement the pH will come out high, so in that case, we will add our acid to the irrigation water in small amounts to measure the pH each time and bring it to the appropriate level.
4. We measure the pH again with the cannabis growing strips as many times as necessary.

To measure pH with a digital meter the process will be the same. We will take care with the sensor of the pH meter and ensure we have done the mix correctly before taking measurements. Beyond this, we will do the necessary tests until the water has the desired levels.

How to regulate water pH?

If the pH of the irrigation water is high and therefore becomes alkaline, we can regulate it with pH correction products such as pH Down, or using natural products such as lemon water or white vinegar. If on the other hand we find a low pH level, that is, we find acidity, we can regulate it with products such as pH Up or raise it with natural products, such as a little baking soda.

Products such as pH Down or pH Up are not organic, but they are still the preferred choice of growers.

How to regulate your substrate pH?

If we notice that our substrate pH is at a level that is not suitable for plants, we will need to regulate it with the irrigation water. In these cases, we should use an irrigation water with a higher or lower pH to compensate to the desired level.

We can measure pH only in the irrigation water, but the more control we keep, the better results we will have in our grow.

From Growlobby we hope to have helped you understand better the importance of pH in cannabis cultivation, and to know the different types of measurements you can carry out. You know you can contact us and visit our online shop to find out more information and discover all the accessories for growing cannabis we have available, and which will undoubtedly improve your self-grow exponentially.