How To Correct pH And Avoid Nutrient Deficiencies

How to Correct pH and Avoid Nutrient Deficiencies
November 18, 2019

It can be readily agreed on by many that home growers all have one single, unison end-goal in mind, and that is to produce as many potent, fragrant, and flavorful flowers as possible.

A grower may provide a plant all the nutrients it needs, and may even employ proper watering and lighting techniques to provide optimum conditions. But, as some cultivators have experienced, these methods do not always secure a smooth sailing journey – some floras may still appear limp and have oddly discolored foliage.

Sometimes the problem isn’t the lack of nutrients. Rather, it could be with the absorption. A fauna may be experiencing some form of nourishment lockout due to the wrong pH level in the growing medium. Growers often overlook this problem, but it can easily be remedied without spending more.

Understanding pH Levels

Watering Marijuana Plant

For some, determining and correcting pH levels may be uncharted territory, but it is an important variable to be considered if one wants to produce healthier yields. To remedy the common problem of mismatched pH levels, one must first know what pH is and why managing it is essential to the growth process.


PH is the measure of acidity or alkalinity of water-soluble substances, which stands for “potential of Hydrogen”. How acidic or alkaline something depends on a scale of 1 to 14. The pH value or middle point of 7 being neutral. Pure water is a “neutral” substance since it has a pH level of 7.

If a sample falls below 7, it is acidic, with the pH value of 1 being the most acidic. The number decreases if the acidity increases. On the other hand, if the values are above 7, it indicates alkalinity. As the alkalinity rises, so does the number in the scale. Hence, the most alkaline solution will have a pH value of 14.

Best pH Level For Cannabis Growing

The pH levels of the growing medium used is vital because cannabis plants typically fair better in slightly acidic environments. It is because soil from the wild, where cannabis plants naturally grow, has a slightly acidic pH level. If the cultivating setup is maintained moderately acidic, it assures the nutrient uptake of plants.

However, as the old maxim goes “one can never have too much of a good thing”. It means an overly acidic medium won’t help roots access the nutrients.

For Soil

For plants to absorb as much nutrients as it needs, the pH level of the soil must range between 6.0 to 7.0. It should be moderately acidic, which as mentioned, is where cannabis floras thrive best.

It is also crucial to note that the pH level of the soil, and even its mineral content, is dependent on what kind one uses to rear plants. Sandy soils are acidic, while clay soils deviate more on being alkaline. The best is usually woodland soil, more commonly known as loam soil, as it is between acidic and alkaline.

The woodland soil is made up of decaying organic materials – leaves, bark, branches, and even living things. As such, it deviates slightly toward a lower pH level, making it acidic.

For Hydroponics And Soilless

Hydroponics and soilless mediums are designed to simplify the process of growing one’s crop. It introduces an environment that allows growers to easily manipulate the conditions, nutrients, and water the plants receive. The optimum pH levels for hydro-growing and coco coir should range between 5.5 to 6.5 pH.

Compared to soil, it is much easier to manipulate the pH levels in hydroponics. Some soilless setups, on the other hand, may require slightly higher pH levels. It is due to the higher amounts of organic matter they contain. As an example, soilless potting mix with worm casting should have pH levels in between the ideal ranges for soil and hydroponics.

Cannabis Water System

Regulating pH Levels

Plants exhibit negative symptoms such as discoloration and stunted growth when not receiving the proper nutrients. As mentioned, the deficiency may be due to inappropriate pH levels in the medium. If not corrected early on, the plant may die or produce a poor harvest.


To be sure that the medium used is not above or below the optimum pH levels, growers must measure it. There is a multitude of paraphernalia and techniques readily-available for the common folk to test pH levels. Two of the most widely used materials are the Digital pH Pen and the pH Measurement Kit with drops or strips.

Digital pH Pen

The device is relatively simple to operate and directly displays the pH level on the screen. Although it does come with a hefty price tag, what it pays off in merits is its simplistic design and accurate and easy-to-read results. The user must be careful in handling the apparatus, though, as it could easily get damaged.

Digital pH pens are regularly calibrated using 4.01 pH and 7.0 pH calibration liquids, which are sold together with the gadget upon purchase.

pH Measurement Kit

In comparison with digital pH pens, the standard pH measurement kit is a more manual approach. It works by using drops or strips that change color. The discoloration indicates how acidic or alkaline the substance is upon comparing it to a color chart.

Instructions on how to use pH measurement kits are relatively simple. Plus, there are plenty of instructional videos on the internet growers can watch as a reference.

Although cheap and straightforward to use, many people consider the use of drops or strips to measure the pH level as inaccurate and hard to read.


Once the grower identifies the pH level of the soil, water, or any potting mix is too acidic or too alkaline, the next plan of action is to remedy the problem by adjusting the pH levels within optimum range.

Hydroponic Setup

  • pH Up. The pH Up adjustment solution is added to help raise the pH levels, which means the medium is too acidic. PH Up generally contains potassium hydroxide and potassium carbonate. The blend allows the pH values to rise very quickly, so it is advisable that growers use tiny amounts and measure the pH value before adding more.

Compared with the potency of pH Down, pH Up has a very weak effect. For the pH up to have the same amount of impact as pH down, it needs a higher dosage of the solution. Therefore, the ratio of pH Up to water is 2 to 4 ml per gallon of water used.

  • pH Down. On the other hand, pH Down is added to bring down the solution’s pH levels. Hence, to make the medium more acidic. The product typically contains food-grade phosphoric acid to bring down pH levels.

As mentioned before, growers must add pH Down solution in minimal amounts and adopt a trial-and-error method as the acidity levels can easily fluctuate. The dose of pH down needed to reduce the pH level by 1 point are 1 ml of pH Down per gallon of water used. Also utilize a blunt-tip syringe for accurate measurements.

Soil Gardening

  • Raising Soil pH. The addition of dolomite lime, hardwood ash, bone meal, crushed marble, or crushed oyster shells has been shown to increase the soil’s pH level. Small amounts of hydrated lime are beneficial in raising pH levels.
  • Lowering Soil pH. If the grower decides to make the soil more acidic, the addition of sawdust, composted leaves, wood chips, cottonseed meal, leaf mold, and peat moss will lower the soil’s pH levels.

No More Nutrient Deficiencies

Even with the best techniques and materials, all the effort goes down the drain if the pH levels of the growing medium are unfit to sustain life. It’s like building a beautiful house with all of the fanciest things and state of the art equipment on an uneven and unfavorable terrain.

Cannabis Attached To A Trellis

Reaping a healthy yield may require high costs, never-ending trial-and-error, and disappointments. With the right materials, though, managing pH levels is simple. And, growers can continue showering the plants with nutrients knowing that every drop is absorbed well.