is marijuana an acid loving plant

The perfect PH value for a cannabis plant

In the world of gardening, pH both affects and is affected by everything. Indeed, the entire process of growing plants is a study in the physical dance of pH balance.


So, you are on your way to growing great cannabis. Your seeds have sprouted, and a small cannabis plant is now eagerly growing. You have spent good money on quality nutrients, and have made sure to properly water and feed your precious plant baby. But something is wrong; you notice your plant appears sick. The leaves are getting discoloured and growth has come to a standstill. Before you know it, your plant is withering away, and you’re stumped as to how this could’ve possibly happened.

Among fatal flaws like overwatering and overfeeding, pH imbalances are one of the most common issues in the cannabis garden. To understand why pH is so important, let us first understand the concept in and of itself.


pH is a measure of how acidic or alkaline something is. The pH scale ranges from 1–14, with a pH of 7 being neutral (the pH of pure water). If pH is lower than 7, a substance is considered acidic (think vinegar or lemon juice). If the pH is higher than 7, the substance is alkaline, as is the case with soaps, bleach, and ammonia.

In more scientific terms, pH level has to do with the concentration of hydrogen ions, say in the water you give to your plants. The pH scale is logarithmic to the base 10, which means that water with a pH of 6 is already 10x more acidic than water with a pH of 7.


As you will already know, all plants require nutrients for healthy growth. They require macronutrients nitrogen, phosphorus, and potassium, as well as micronutrients and minerals including calcium, magnesium, iron, copper, and a whole lot more. If plants cannot access these nutrients, it will lead to deficiencies and other serious health problems.

The issue with cannabis plants is that they are only able to take up nutrients within a small pH window, which ranges from about 6–7 when growing in soil. If the pH is lower or higher than that, the plant cannot take in nutrients, even if they are present—thus spurring nutrient deficiencies via “nutrient lockout”.

In those places where cannabis thrives in the wild, the soil is normally slightly acidic; therefore, homegrown cannabis plants will also prefer a slightly acidic environment. However, the way that you grow cannabis also plays a role in the optimal pH level for your plants. Cannabis grown hydroponically or without soil needs an even lower pH than a soil grow.


SOIL: 6.0–7.0 pH

If you grow in soil, the optimal pH level for the root zone is between 6.0 and 7.0. However, there is no set number within this range that is “best”. Instead, it can be good to allow for some natural fluctuation within this window to support optimal nutrient uptake. So as you adjust, try a slightly different reading each time. You can, for example, adjust your pH to 6.2 for one watering, then 6.6 the next. As long as it stays within 6.0–7.0, you should be fine. Soil is also more forgiving when it comes to pH imbalances, but it can only give so much.

If you grow purely organically—where you do not administer liquid nutrients—pH is less of an issue. If you’re using amended and composted soil with organic matter, the microorganisms within will make the nutrients more available to the roots. However, most growers using standard potting mixes and liquid nutrients will indeed have to reckon with pH.


Hydro and soilless grows are a different beast when it comes to pH. If you grow soilless, say in coco, the optimal pH level at the root zone should be somewhat lower than in soil, between 5.5–6.5. The same goes for all methods of hydro.

With these methods, it is just as important that you allow the pH level to fluctuate across the acceptable range to support nutrient uptake. For example, in hydro, calcium and magnesium are mostly absorbed at pH levels above 6, while other nutrients like manganese prefer a slightly lower pH.

Then again, this shouldn’t be an issue since pH levels will naturally change slightly with each feeding in a hydroponic setup. You will only need to correct if the pH level exits the optimal 5.5–6.5 pH range.

When growing in coco, perlite, or hydroponically, you are in charge of administering nutrients directly to the root zone via the water, which means that huge pH fluctuations are more of a risk than in soil. The inert media used in hydro and soilless grows merely retains water and provides support for the roots of your plants. So when administering nutrients, be careful that you don’t overload your plants.

In the world of gardening, pH both affects and is affected by everything. Indeed, the entire process of growing plants is a study in the physical dance of pH balance.

Cannabis pH and How It Affects the Health of Your Plants

Maintaining the proper pH of your cannabis plant’s growing medium and water can determine your plant’s ability to absorb nutrients and grow big, beautiful buds.

As with all plants, proper growing conditions help the cannabis plant to thrive. Keeping your marijuana plants growing in the ideal pH will boost plant size, flower production, and even the levels of valuable cannabinoids generated by the plant.

Today, we will be taking a look at soil and water pH and how proper cannabis pH affects the overall health and cannabinoid production of your plants.

What is pH?

When we are discussing pH, we are talking about a measure of acidity or alkalinity of water soluble substances (pH stands for ‘potential of Hydrogen’). The pH scale runs from 0 to 14, with lower numbers being acidic, higher numbers being alkaline, and 7 being the neutral middle point.

Each plant found in nature has its own pH identity, with some plants being more acidic and others being more alkaline. The water of different regions also has a pH identity that is determined by a variety of environmental factors. Finally, the soil of various regions will have a unique pH identity. Due to these fluctuations in pH based on plant, water, and soil types, it is important to test any plants you are growing to see if they are in the correct pH range. PH can be measured by testing kits or specially designed pocket sized digital testing pens.

Supplements added to your plant’s water, including ones that will raise and lower pH, help you dial in an ideal pH level. These products are available at most garden centers and from online grow shops. These pH affecting products are universal for gardening and can be used on almost all plants in your garden, not just your cannabis.

What is the Cannabis pH Value?

Keeping a correct pH in your cannabis plants’ grow environment helps prevent nutrient deficiency that can stunt growth and result in a lower yield of marijuana buds. The cannabis plant prefers a slightly acidic pH environment of about 6-6.5.

When the pH environment rises in alkalinity above 7.5, the roots of the cannabis plant are not able to consume the available iron, copper, zinc, and manganese in their vicinity. When the pH lowers into an acidity of less than 5, the roots are not able to access phosphoric acid, calcium, and magnesium because they lose their solubility.

Correct pH allows the cannabis plant to properly access nutrients in its soil in order to grow its best. When setting up your garden to grow cannabis, it is always best to conduct a simple test to determine the pH identity of the soil and water.

Improper pH can keep the plant from growing as healthy as it could be and can affect the ultimate levels of cannabinoids and terpenes in its flowers. Proper pH can also affect how large and how quickly the plant can grow.

If soil is alkaline, adding compost to the soil before the growing season will add nutrients and make the soil more acidic. The pH of soil can also be affected while the plant is growing using pH up and pH down products that are applied when watering your cannabis plants.

You can test the pH of both your water and soil using commercial pH tests to ensure your cannabis plants are in the best possible growing conditions.

  1. Add nutrients to the water that you will feed your plants.
  2. Test the water you will give your marijuana plants and adjust pH accordingly, aiming for a pH of 6.
  3. Water your marijuana plants.
  4. To also test the pH of soil, test early water runoff from soil after you water your maijuana plants.

If runoff pH is…

  • in the right range, no changes or additional steps are needed.
  • too low – provide next watering at pH 6.5 – 7
  • Too high – provide next watering at pH 5 – 5.5

Influence of pH on Cannabis Quality?

Healthy, happy cannabis plants create the highest quality buds. When marijuana plants are able to absorb available nutrients in their soil, they can grow tall and strong and generate the high cannabinoid and terpene content you’re hoping for in your buds. This can be accomplished by keeping the soil and water with which they are grown within an ideal pH range for the cannabis plant.

When the pH of a marijuana plant’s growing conditions falls outside of its normal, ideal range and nutrient deficiency begins, you will begin to see signs that include yellowing of leaves, brown spots on leaves, and dropping of leaves. Plants suffering from nutrient deficiency can also be more susceptible to pests and disease and can experience reduced flowering.

If these problems persist, even when you have an ideal pH in your garden, then you may need to add nutrients like potassium, nitrogen, and more to your growth medium through a fertilizer.

Want to Learn More About Growing Your Own Marijuana?

Visit our Cannabis 101 page , where we outline some of the most important topics for those just starting out with marijuana, or you can visit our at-home grow guide here .

You can also make your own DIY cannabis concentrates using your homegrown cannabis plants. Here’s how.

Maintaining the proper pH of your cannabis plant’s growing medium and water can affect your plant’s ability to absorb nutrients and grow big, potent buds.