The Art of Adjusting pH Levels to Grow Big Fat Cannabis Buds

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Added 14 October 2022

When growing cannabis, you have to consider various environmental conditions, such as temperature, relative humidity, and much more. One such consideration is pH, which may seem minor at first glance but is perhaps one of the most important factors for better plant growth.

pH does not only relate to the quality of the nutrient solution or the soil, but it dictates how well your cannabis plant can absorb nutrients while growing a healthy root network. And if the pH is perfect for your plant, you not only get a bushy plant but also juicy buds unlike ever before.

The art of adjusting pH is intricate. Although it's easy, you need to be meticulous. It is not as simple as adding a pH balancer to the water solution.

So, how to adjust pH levels to grow fat cannabis buds?

Read on...

What is the pH Scale?

What is the pH scale

pH stands for the potential of hydrogen in a solution, and it ranges from 0 to 14.0. In layman's terms, pH is the number of hydrogen ions in a specific solution. Essentially, pH gives you an insight into the interaction of various chemical compounds with each other according to their ionic state.

Practically, pH refers to the acidity or alkalinity of a solution. If the pH of a solution is less than 7.0, the solution is acidic, and if it is greater than 7.0, the solution is alkaline. Deionized water, or RO water, has a pH balance of 7.0 since there are no hydrogen ions in it. 

The thing about pH is that the scale is logarithmic — even small changes in the values can lead to significant differences in the acidity or alkalinity of the solution. For instance, pH 3.0 is ten times more acidic than pH 4.0. This can affect the state of nutrients in a solution for cannabis plants.

How Does pH Affect Cannabis Plants?

How Does pH Affect Cannabis Plants?

We know what pH is, but what role does it play in the growth of your cannabis plant? Here’s how.

1. Benefits of Proper pH for Cannabis Growth

Cannabis plants need an array of nutrients to grow properly, including macronutrients like nitrogen, phosphorus, and potassium, and micronutrients like calcium, iron, magnesium, and copper. The correct pH balance determines how the plant’s roots absorb these nutrients.

One of the major benefits of maintaining the right pH level as per your setup is that your plants can grow even more vigorously. Correct pH levels enable the roots to absorb nutrients efficiently, so the plants tend to grow healthier and taller. 

Maintaining the right pH balance ensures your plant grows well, so you can also spot pH imbalances early on. This minimizes the risk of nutrient deficiencies. However, if they do occur, it is easier to pinpoint the cause since you know your pH is spot-on.

Another benefit is a monetary one. You are probably spending a lot of money on the right nutrients. If the pH level is not correct, the plant may fail to absorb the nutrients, rendering your efforts of purchasing the best nutrients worthless. That’s a massive waste of money. 

2. Problem with Wrong pH Levels

Cannabis plants prefer pH levels that are slightly acidic, so when the pH balance is not slightly acidic, it can lead to various problems in the plant. And wrong pH levels create an antagonistic condition for these nutrients, making them either unavailable or excessively available for the plants. 

Improper pH levels can inhibit the functioning of various biochemical pathways via which the roots absorb and transport nutrients to the plant, causing a nutrient lockout. So, the plant may fail to absorb nutrients from the soil even if they are in abundance, leading to nutrient lockout.

For example, if the pH is low, micronutrients like manganese and iron become more soluble, leading to toxicity in cannabis plants. On the other hand, when the pH is too high, micronutrients become less soluble, leading to nutrient deficiencies. 

This is why the wrong pH level is the most common reason for nutrient lockout and deficiencies.

Unless you are growing a cannabis plant in naturally acidic soil, you need to pay attention to the pH levels, especially in hydroponic or soil-less setups to ensure proper growth of the plant.

3. pH Fluctuations While Growing Cannabis

Maintaining the pH levels when growing cannabis is essential for good growth and harvest, but they sometimes fluctuate due to various reasons. When these fluctuations occur, they hamper the roots’ ability to absorb nutrients properly, leading to lower resin production or bud development.

This is why it is essential to monitor pH fluctuations on a regular basis when growing cannabis. Even if the pH seems alright right now, it can fluctuate a little and cause problems later down the line. Thus, monitoring pH levels is an essential step in growing cannabis.

What is the best pH for Cannabis Plants?

Cannabis likes slightly acidic conditions — this is where it grows best — but the window of pH for cannabis plants is quite narrow. Here are the best pH ranges for cannabis plants in various growth conditions.

Best pH for Cannabis Growing in Soil

Soil pH chart

The ideal pH for cannabis plants growing in soil is from 6.0 to 7.0. But remember, there isn't a single best point or number. In fact, it is good to let the pH fluctuate a little within this range so that the roots can absorb all the nutrients properly. This is because some nutrients get better absorbed at lower pH than others.

For example, you set the pH at 6.3 while watering, but it is at 6.5 the next day. As long as it is within the recommended pH window, you don’t have to worry much. Growing cannabis in soil is forgiving with regard to pH imbalances.

pH for soil-based cannabis plants is less of an issue especially if you are growing your plant organically, where you don’t administer any mineral nutrients. In organic soil with microorganisms, the pH is maintained by the organisms and they also make the nutrients readily available for plants. However, you need to pay close attention to the pH levels and maintain them when you're using other pot mixes or mineral nutrients.

Best pH Levels for Hydroponic Cannabis

Hydroponics pH chart for cannabis

If you are growing cannabis in a hydroponic setup or don’t use soil, maintaining the right pH levels becomes even more essential. For such setups, the ideal pH range is slightly lower than that of soil, i.e., from 5.5 to 6.5 for optimal plant growth and yield.

The same fluctuation principle applies here, too — let the pH fluctuate slightly, as long as it is between the range of 5.5 and 6.5 

But you need to pay more attention to these fluctuations nonetheless. This is because pH fluctuations outside of the recommended range can cause significant problems because you administer the nutrients directly to the root zone. 

What are the Signs of Wrong pH Levels in Cannabis?

pH is a common cause for a variety of problems on cannabis plants, most of which show up physically. So, it is easy to spot any pH problems just by looking at how your plant is growing. Here’s how.

Signs that pH is too Low

pH too low

When the pH in the root zone is too low, it indicates acidic conditions. One of the first signs you may see is discoloration of the leaves and slowed-down growth. Other symptoms also include nutrient deficiencies. 

Other signs of low pH in the cannabis plant include leaf chlorosis, leaves turning dark green, leaf necrosis, tip burn, twisted or withered leaves, etc. 

Signs that pH is too High

pH too high

High pH levels indicate alkalinity in the root zone, which is also bad for your plant’s growth. In such conditions, elements like iron may not be absorbed properly by the roots, causing a variety of issues, including nutrient lockout and deficiencies. 

Usually, the first sign of the root zone being too alkaline is on the leaves — they start losing color and turning yellow. At the same time, the plant may not grow as vigorously and show other signs of stress. Other symptoms include leaf chlorosis, tip death in new growth, leaf necrosis, brown spots on leaves, etc.

Usually, low or high pH levels are caused by a few common reasons, such as the following:

  • A dramatic shift in the local water supply’s pH levels
  • Wrong formulation of the nutrient solution
  • pH adjusters being used excessively 
  • Incorrect use of nutrients or other compounds that are used in the nutrient solution or added to the growing medium

And it’s difficult to say how fast your plants can recover from incorrect pH levels. It depends on various factors, including your plant’s genetics, resistance to stress, the severity of the imbalance, and how well you've cured it. Unfortunately, your plant may not recover at all in severe cases.

How to Test Root Zone’s pH When Growing Cannabis?

How to Test Root Zone’s pH When Growing Cannabis?

As mentioned earlier, an essential step in maintaining the right pH for cannabis plants begins with testing the pH regularly. And doing so is easy. Here are a few ways you can test the pH of the plant.

1. Use pH or EC Meters

The easiest and most accurate way of monitoring the cannabis plant’s pH levels is using pH or EC meters. They are inexpensive and readily available in most local gardening stores and online stores. Plus, unlike pH test strips, you can actually use pH meters for years and they are easy to understand.

Here is how to use pH or EC meters to test the pH:

Step 1. Calibrate the pH Meter

Whether you have bought a high-quality pH meter or a substandard one, it is a good idea to first calibrate it against a known standard. In this case, use RO water (since it has a neutral pH of 7.0) and set your pH meter accordingly.

For most meters, you simply have to submerge the probe in the water and adjust the display to 7.0. But this may differ from one manufacturer to another. Refer to the owner’s manual to know more about how to calibrate your pH meter.

Step 2. Test the Nutrient Solution

The next step is to test the nutrient solution of cannabis. Again, submerge the pH probe into the solution and the meter will display its accurate pH on the screen.

Step 3. Test the Growing Medium

The final step is to test the growing medium’s pH, as it can sometimes differ from the nutrient solution due to salt buildup or wrong drainage. To do this, test the drainage water from the plant container and compare it to the nutrient solution’s pH. Ideally, the pH of the nutrient solution and runoff water should be close to each other. 

2. Use pH Drops

On the other hand, you can also measure the pH using drops or pH kits, which come with a test tube, testing solution, and pH chart. Using these kits is simple but you need to dispose of them after one use. Here’s how to use them:

  1. Prepare the nutrient solution as usual but don’t oxygenate it by stirring it too much
  2. Fill the test tube halfway with the nutrient solution and add 3 drops of testing solution (or as recommended by the manufacturer)
  3. Then, gently shake the test tube 
  4. Within a couple of minutes, the mixture will change its color. Compare it to the pH chart to know the pH of the nutrient solution
  5. Follow the same steps with the water runoff after watering to know the pH of the root zone

How to Adjust the pH for Optimal Cannabis Growth?

How to Adjust the pH for Optimal Cannabis Growth?

When you test the pH, sometimes, you may find the levels to be way off. That’s a problem but, fortunately, an easy one to fix. But you must do it quickly before it starts affecting your plant severely. Here are a few ways to adjust the pH to ensure your cannabis plants grow the biggest buds.

Use pH Up/Down Products

The most common way of adjusting the pH of the nutrient solution is to use pH up/down products that you can buy from your local gardening store. These products contain compounds that can either increase or decrease the pH of the solution when added. Here’s more on them:

pH Down Products

The pH of the nutrient solution is high for most people that face a pH imbalance with their nutrient water. This is because the water supply is alkaline in most regions. In such cases, you can use pH-down products to lower the pH until they are at the desired levels.

pH Up Products

On the other hand, the water may be acidic in some regions, in which case, you may have to use pH-up products to bring the pH levels up. 

Mineral vs Organic pH Adjuster Solutions

pH up/down products come in two forms — organic and mineral — both of which have their own benefits. 

Mineral pH adjusters usually contain the following compounds:

  • Nitric acid, which is perfect for the vegetative stage of cannabis due to its high nitrogen levels
  • Potassium hydroxide, which is used to increase the pH levels and is ideal for both vegetative and flowering periods
  • Phosphoric acid, which is used to lower the pH and is best suited for the flowering stage

On the other hand, organic pH adjusters tend to contain the following compounds:

  • Citric acid, which is used to decrease the pH levels and is suitable for all growth stages of the plant
  • Humic acid, which can increase the pH level, is not suited for the flowering stage since it can reduce THC content in the buds

The main difference is that mineral pH adjusters can harm organic soil, requiring a replacement after each use, which is not a problem with organic pH adjusters for cannabis. 

How to Use pH Up/Down Solutions?

Both the pH up and down products work the same way — the only difference is the direction they push the pH of the solution. Here are the steps for using pH up/down solutions:

  1. Fill your reservoir tank with the nutrient solution and let it settle for a few minutes
  2. Use your pH meter to measure the pH of the solution
  3. Then, add a small amount of pH up/down product to the solution and mix well 
  4. Recheck the pH after a few minutes and add more, if required

How Much pH Up/Down Should I Add?

How much pH up or down you use depends on a variety of factors, especially the quality of the water. For instance, soft water requires smaller amounts of pH adjusters since they are largely devoid of minerals. On the other hand, hard water may require you to add more. 

Usually, you need to add pH down the solution to the water in larger quantities. Most pH-down solutions reduce the pH of water by 1.0 when you add 1 ml to a gallon of water. On the other hand. pH-up solutions are not as potent, so you may need to add 2 to 4 ml per gallon of water to raise the pH by 1.0.

While this is just a general guideline, you must always refer to the manufacturer’s instructions. Some pH up/down products may require different processes.

Alternative: Use Natural Products to Adjust the pH of Cannabis

You can also correct the pH of the root zone by using natural products. These products are slow-acting, but they also encourage life in the soil, which leads to better plant growth. This is because such natural products promote healthy bacteria and fungi activity in the soil.

Common natural products that you can use to adjust the pH of cannabis include compost, manure, worm casting, pine needles, compost tea, lemon juice, vinegar, lime, wood ash, etc. 

How to Adjust pH Properly for Cannabis Plants?

How to Adjust pH Properly for Cannabis Plants?

The above tips can help you get the job done, but you don’t want just that. You need to do the job as best as you can. So, to help you along the way in adjusting your cannabis plant’s pH, here are a few tips that you must keep in mind:

  • Don’t Be Generous with pH Solutions

In most cases, the more the merrier, but when it comes to pH adjusters, the same principle does not apply. Ideally, you should always err on the side of caution and add just a little pH adjuster solution to the water. Adding too much can push the pH in the other direction and may require you to add other pH adjusters to bring the levels back to normal, forcing you to add more and more minerals to the nutrient solution than required. 

  • Use Tap Water Instead of RO Water

There are two benefits of using tap water instead of RO water. The first is that tap water is already rich in various minerals that your cannabis plant can benefit from.

The second benefit is that RO water’s lack of minerals makes it easy for other minerals to push the pH out of balance. Tap water has other minerals that offer a buffer to the solution, preventing drastic pH changes in the nutrient solution. 

  • Avoid Mixing Nutrients Directly 

When making your nutrient solution, add nutrients one by one to the water instead of mixing them all together. Sometimes, some minerals or nutrients may interact with each other and alter the pH levels of the nutrient solution. 

  • Shaking the Water can Change the pH

Many growers like to give their nutrient solution a good shake to ensure everything mixes well, and hydroponic setups with oxygenated water can also have higher than average pH. This is because shaking oxygenates the water, which slightly increases the pH.

If you are hand-pouring water on your plant or using a hydroponic setup, this pH fluctuation is completely normal and you don’t have to worry about it. But when you are mixing the solution, do it gently so as to not change the pH during this time. Only shake the water or oxygenate it after it has been pH adjusted for cannabis. 

  • Don’t Sweat at Every pH Drift 

Your goal is to keep the pH of the solution in the recommended range, but don’t panic if the pH fluctuates slightly. pH tends to fluctuate sometimes. As long as it’s in the recommended range, the pH is safe for the cannabis plant. You should only adjust the pH if the levels go beyond the recommended range. 

Summary: The Art of Adjusting pH Levels to Grow Big Fat Cannabis Buds

pH may not seem like a big deal while growing cannabis — who cares if the water is a little acidic, right? 


The pH of the nutrient solution is perhaps the most important aspect of nutrient delivery and forms the foundation of a healthy cannabis plant.

If you want to grow big, bushy buds and have a successful yield, it is imperative that you monitor the pH regularly and adjust it whenever it strays out of the recommended range. Do this and you will avoid most problems related to nutrition unless you have missed out on an important nutrient while making the solution. 



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Guter Beitrag. Sehr aufschlussreich und informativ.
very good article. I think this is the biggest problem with beginner growers. ph value and ec value are essential for healthy plants and thick buds.