Water is essential to life as we know it and a useful tool for understanding what’s going on in our garden or farm environment. To truly uncover the mysterious power of water and how it is crucial for nutrient maintenance, we need to measure the pH of the soil or water our plants grow in. You see, pH levels determine whether or not essential mineral nutrients are available for plant uptake, and a pH nutrient chart is our key to finding that optimal, slightly acidic “sweet” spot.
There are many pH nutrient charts you can find across the internet. Generally, the most important components illustrated are these:
- The 13 essential nutrients for growing healthy plants.
- At which pH the availability of each nutrient is most available for absorption or uptake.
Plants thrive in consistent, stable environments. An excellent measurement system and tool for us to monitor soil or hydroponic environments is the pH level. Understanding a pH nutrient chart for plants is a bit like using a BMI chart to find a healthy weight range. There’s not one exact number that is always right, but it is an excellent tool for plant growers to understand plant nutrition better.
If your plants are struggling despite having a balance of nutrients, the problem may be that the pH level of your soil or water isn’t in the right condition for nutrient uptake to occur. Read on to learn more about how you can use the pH nutrient uptake chart to obtain optimal nutrition for your plants.
What does pH measure?
We use pH scales to measure how acidic or how alkaline water-based solutions are. Acidic (sour) solutions have a lower pH, betweeen 0 and 7. While alkaline (let’s call this basic or sweet) have a higher pH, between 7 and 14.
The magic middle number 7 indicates a neutral pH. Pure water has a pH of 7.
The “pH” or “potential hydrogen” measures the availability of hydrogen ions (H+) or hydroxide ions (OH-) as water transforms. If water breaks down, the concentration and ratio of these two ions change. So, at a pH of 7, there is an equal number of hydrogen and hydroxide ions. This video is a great visual breaking the whole ph system down for you.
To understand the range of acid to base in lay terms, we have a handy list for you. Here are some everyday items that fall on the scale, starting with most acidic and increasing to the most alkaline:
- Stomach Acid
- Pure Water
- Sea Water
- Baking Soda
- Drain Cleaner
So why do we need to know pH again? Well, for example, you know from common sense that you shouldn't be pouring bleach in your garden. The pH scale helps define which zones are the safe and healthy ranges for what should be in your garden.
The essential nutrients your plants need all fall in a similar range. Understanding pH will help you better understand how to read a ph nutrient chart.
The Ideal Plant pH Range and How it Affects Plant Nutrient Bioavailability
There is a very specific pH range where all the essential, good-for-your-plant nutrients jive in harmony. Generally, that range is between 5.5 and 7. Recommendations from sources will have slight variations depending on region, crop, and the growing medium.
It's important to take note that within this specified range, certain plants may perform well while others will suffer. Just as we as humans all have unique and varying total nutrient requirements or deficiencies to remedy, different plants also have their own slightly varying requirements. We as gardeners and farmers need to remember that!
For example, within the ideal pH range, different types of plants can endure or even prefer higher or lower pH levels. Mountainous, wild blueberries and even standard crop potatoes thrive in acidic soil (closer to a pH of 5-5.5). In contrast, vegetables and grasses perform better in only very slightly acidic soils (pH 5.8-6.5).
What Happens When pH Ranges Are Not In Balance
Plants have systems that seek homeostasis and balance. However, there is only so much they can do alone. If the pH environment is preventing them from creating a healthy internal cellular structure or stunting their production of photosynthesis, it won't be pretty.
Low pH or Acidic Soil: In acidic soil, problems such as aluminum, manganese, and hydrogen toxicities can occur. Often, you will also find that there are deficiencies of essential micronutrients such as calcium, magnesium, molybdenum, and phosphorus.
High pH or Alkaline Soil: Not as severe a problem as acidic soil; however, it can be a problem for nutrient availability and cause issues like iron deficiency. It’s worth noting certain plants thrive in a higher pH environment such as asparagus, cauliflower, and cabbage.
A pH nutrient chart helps you to understand at what pH that balance occurs. If not, plants will have a hard time carrying out physiological processes.
If you notice your plants' leaves are turning yellow or not flowering, we suggest testing the pH. Remember, monitoring and maintaining a healthy pH level in your soil or hydroponic solution is important to the overall nutrition of your plant.
Understanding the pH Nutrient Chart
The pH nutrient uptake chart displays the essential mineral nutrients plants need. Each horizontal line represents one of these nutrients.
The thickness or thinness of the line indicates how readily available the nutrient is at specific pH levels.
There are 13 essential nutrients included on the standard chart. While these aren't all the nutrients, they are the most common and some of the most important.
It's important to understand that these nutrients exist in many different states. Only when the right pH levels exist, they can transform into the perfect mineral state which plants can access and utilize.
Plant Macronutrients, Secondary Plant Nutrients, and Micronutrients
You might be surprised to learn that just as humans have micronutrient and macronutrient needs, so do plants.
Plants don’t need protein, fats, and carbohydrates, but they do have other specific macronutrients and several micronutrient requirements for optimal health.
Nutrients in plants work to build up cells and enzymes of the plant itself while others implement chemical processes such as photosynthesis. Read on to learn more about these essential nutrients for your plants. We include the standard 3 available in air and water and then focus on the 13 available as mineral nutrients.
6 Primary Macronutrients for PlantsWhile humans have only 3 macros to worry about, plants have 6:
- Nitrogen - Building block of plant proteins (#1! → Plants need more of this than any other nutrient).
- Phosphorus - Essential in the formation of DNA and RNA and for energy storage and transfer.
- Potassium - Regulates metabolic processes and growth.
- Non-mineral nutrients: Carbon, Hydrogen, and Oxygen are available in air and water.
- Mineral nutrients: All other plant nutrients must be available for uptake in mineral form. Nutrient uptake of these other nutrients can only occur once the mineral breaks down from an organic compound into an inorganic compound. Often microorganisms or fungi work in the soil to optimize this process.
The 3 Secondary Plant NutrientsPlants also need:
- Calcium - Crucial component of cell wall strength.
- Magnesium - Helps absorb sunlight through photosynthesis & is the core ion of Chlorophyll.
- Sulfur - Also essential to the composition of chlorophyll and helps metabolize the micronutrient nitrogen.
7 Plant MicronutrientsAlso known as trace nutrients, only a tiny amount of these nutrients are necessary. They are often crucial to the utilization of the macro and secondary nutrients.:
- Boron - Regulates the metabolism of carbohydrates.
- Chlorine - Required in photosynthetic reactions.
- Copper - Activates enzymes for growth processes, and deficiency affects protein synthesis.
- Iron - Assists in the formation of chlorophyll and necessary to biochemical processes such as respiration, photosynthesis, and symbiotic nitrogen fixation.
- Manganese - Assists in the formation of chlorophyll and activates enzymes for growth processes.
- Molybdenum - Enables plants to utilize macronutrient nitrogen.
- Zinc - growth regulator and involved in chlorophyll and protein production.
Other nutrientsSome plants prefer certain nutrients that might be harmful to other plants. Nutrients such as nickel, silicon, and cobalt are on this list.
All the nutrients highlighted in the pH nutrient chart are soluble in water solutions at the pH levels indicated. This means that the nutrients are in the optimal zone for uptake and absorption by the plants roots.
Adjusting and Optimizing pH for Nutrient Uptake
Now you can see which nutrients are essential for your plants and which pH zones are the best. Since nutrient availability is critical to your plants, maintaining a pH level that is best for your plant on every level.
An acidic soil pH (below 5.5) can wreak havoc on your crop and negatively affect nutrient management. Whereas a highly alkaline soil or hydroponic solution will decrease the nutrient availability of essential nutrients.
How to Test pH in your soil or water
The first thing to do is know what the pH is the water or soil you are using.
There are many at-home methods available to test the pH yourself. Some must be manually conducted, and others you can set up to constantly monitor the pH levels.
- Test Strips / Litmus Test Strips
- pH Chemical Test Kits or Liquid pH Test
- Digital pH Tester or Meter (Using a pH electrode)
Maintaining Healthy pH Levels in SoilSome of the best ways we’ve found to maintain healthy pH Levels, particularly for soil-based environments, is to develop optimal nutrient uptake environments:
- A microbe-rich liquid nutrient solution: Amplify (Natural bacteria solution to support the active environment in the soil existing around the root system (rhizosphere). These bacteria are proven to promote practically instantaneous macronutrient and micronutrient uptake)
- Organic Matter: Manure, grass clippings, leaves or straw, mulch, etc. (takes time)
Adjusting Soil pH
Soil pH is affected by rainwater, parent materials (from existing rock formations), and fertilizers.
Farmers and gardeners often keep an eye on the pH of their soil to monitor nutrient absorption. The easiest method for maintaining soil pH is to develop a natural, organic system that stays in balance over time.
As we’ve said, maintaining soil pH affects nutrient uptake and leads to healthier plants. So, what are you supposed to do if you test a soil sample and find that something’s off?
Acidic soil, which is soil that is lower on the pH scale (around 5.5 or below), can seriously damage your plants. Here are the most common ways to increase soil pH:
- Liming Materials: pulverized, granular, pelletized and hydrated limestone
- Wood Ashes
Remember, some plants prefer more acidic soils. Make sure that you check the type of plant you are adjusting the pH to ensure the optimal pH uptake environment.
Regularly testing soil samples for pH levels will also help make sure you stay within the proper ranges.
Alkaline soil often occurs in certain regions due to existing minerals in the underlying earth. When a soil test indicates high alkalinity, nutrients are less available. So, plants develop nutrient deficiency. Common applications to lower the alkalinity include:
- Elemental Sulfur - takes time, as it requires the help of soil bacteria to convert
- Aluminum Sulfate - fast response
Hydroponics and Adjusting pH
The word itself, “hydroponic”, is derived from Greek roots and roughly translates to working with water.
In hydroponic systems, a plant grows in a soilless environment using alternative grow mediums. These mediums do not offer the same benefits as soil. So, water is the primary carrier and conductor (laborer) involved in nutrient uptake.
One of the many benefits of this type of system: it allows roots to have more direct nutrient absorption.
Hydroponic Nutrients Guide
Generally, hydroponic solutions come with ready-made nutrient salts that work to supply nutrients directly to your plants. However, because plants must absorb nutrients swiftly in this type of system, it’s important to monitor the pH levels. Otherwise, your nutrients will become unavailable or dissolve into a form that your plants can’t utilize.
Nutrient salts not only supply your water with essential nutrients but affect the conductivity of the solution. Electrical conductivity (EC) must be monitored along with pH to provide the optimal environment for your specific plants.
Water pH Levels: Crucial for Water Soluble Plant Nutrients
The beauty of hydroponic systems is the incredible clarity a grower can have with their system if they invest in the right tools.
You can add nutrients, purify your water to battle the limitations of tap water or hard water, or simply add a small amount of various pre-made solutions to directly affect plant growth.
Water testing is standard practice in a hydroponic environment as it is the fundamental building stone of your system.
With all the impurities that make their way into our current water and without soil to filter these out in hydroponic systems, you need to know your water. Whether you use tap water or distilled water, monitoring pH is crucial to ensuring your nutrients are available for uptake.
Adjusting pH in Hydroponic Environments
To adjust pH in hydroponic solutions is super simple. There are premade solutions or kits that can be used in your system to increase or decrease the pH accordingly.
These solutions are easy to understand and apply to your hydroponic system as long as you know which direction your pH needs to be adjusted. These premade solutions are called pH up and pH down.
- To increase pH, use pH up.
- To decrease pH, use pH down.
Hydroponic micronutrients must also be added directly to your solution, but if the pH isn’t on target you will lose out on the nutrient uptake that should occur.
Whether you choose organic hydroponic nutrients or commercial hydroponic nutrients is up to you. The one limitation of hydroponic solutions is that natural, organic microorganisms and bacteria that live in soil and support root systems aren’t present.
The solution? You can add an organic liquid solution teeming with beneficial organisms. We've found great success with Amplify, it can also boost plant growth and even optimize plant nutrient uptake.
What is pH Drift and Why Does it Happen?
Have you set your pH to a certain level, only returning later to find it has somehow gradually increased? You are probably wondering why this is happening.
That’s pH drift!
Hydroponics solutions are not entirely controlled systems. They are an active method to feed your plants and need to be constantly monitored to ensure optimal plant nutrition.
Think about it, the water and nutrients are constantly being absorbed by the plants. This changes the nutrient ratio and affects the balance of the pH. Generally, the pH drifts up.
Why? The nutrients plants need are slightly acidic. So, when the plants absorb these nutrients, they leech the solution of these nutrients, causing the solution to drift to a higher pH. This isn’t a problem, it’s just an indication that your plants are feeding and you need to add in more nutrients!
To illustrate, say you set the pH to 5.5 having added nutrients (which are typically acidic, i.e. lower on the pH scale). As the plants take in the nutrients, they absorb those acidic components of the water solution. Inevitably, your water solution gradually drifts to a higher and higher, more alkaline pH level. When you come back to check your pH, it’s now at 6.0 or higher and devoid of those nutrients.
Adding in more nutrients for your plants and adjusting the pH is all you have to do. In hydroponic solutions, pH drift is simply something you must be aware of and monitor.
Rockwool and pH Drift
Rockwool is a popular growing medium for hydroponics. Also known as stonewool, rockwool is made from basalt. It’s valued for its ability to hold water, the ability to retain oxygen, and can accommodate a wide range of plant growth.
When it comes to pH, rockwool is very alkaline. It is important to be very diligent in monitoring your pH and make necessary adjustments to maintain optimal nutrient absorption if you are using this medium. Changes in pH can occur rapidly, sometimes in a matter of hours and cause nutrient lockout.
Some advise pre-soaking the rockwool medium in a slightly acidic (5.5 pH) solution to best prepare it for nutrient absorption.
Bioavailability of Nutrients in Plants for Our Own Bodies
Many of the essential nutrients that plants employ are ones that humans need as well. One of the biggest, recent controversies in plant health has been the depletion of soil health. This has greatly impacted the availability of nutrient bioavailability when we eat plants.
That’s another reason why nutrient health is so important!
Of course, healthy plants will and should be able to nourish us with these nutrients. Keep in mind that the rigid cell wall of plants that is able to survive long seasons can make nutrients less bioavailable when consumed. That’s why certain foods when lightly cooked or well chopped, can release or allow higher nutrient availability.
Use the pH Nutrient Chart to Hack Your Way to Beautiful Plants
Whether your plants seem to be struggling or not, using pH will ensure maximum nutrient absorption.
We hope that this guide to pH and nutrients helped to break down the ins and outs of how a pH nutrient chart can help you grow stronger, healthier plants.
Important things to remember about the optimal pH for plants and nutrient uptake:
- It is not necessary to maintain a neutral pH of 7, but generally, a slightly-acidic environment is a good rule of thumb, so between 5.5-7.
- It is typically good practice to maintain a pH that is greater than 5.5 because below that is when many of the essential nutrients become unavailable to plants (also called nutrient lockout) or elements such as Al and Fe can become toxic (to certain plants).
- If your plant is demonstrating signs of a nutrient deficiency, your soil or hydroponic solution may not lack the nutrient but rather be at a pH level that causes nutrient lockout. So, simply modifying the pH will allow the nutrient uptake process to occur.
- Worms and healthy bacteria that support optimal soil environments, also like slightly acidic conditions. In the absence of soil, or to support root uptake in soil gardening, adding liquid microbial blends such as Amplify improve nutrient uptake results. Adding a microbial blend to hydroponic solutions is also a great way to enhance plant growth!
- Monitoring the pH is an ongoing process and doesn’t require exact precision. Just maintaining a pH within the optimal range, and if it gets too high or too low, you can then adjust.
Don’t forget that there are always other influencers beyond the pH level. Your water, soil, and plant type will all have an influence on the system at work and impact what the “ideal” range may be.
Being attentive to your plants and monitoring them on a regular basis is very important. Even if you have scored the perfect pH range, there is a chance that you encounter other deficiencies or pesky plant diseases like powdery mildew.
Gardening is a constant adventure! The thing is, there is always a reward when you uncover the remedy or solution to an obstacle: healthy, thriving, and beautiful plants!
- Clemson University - Home & Garden Information Center
- ResearchGate - Soil pH Affects Nutrient Availability
- Utah State - Solutions to Soil Problems
- University of Missouri - Soils, Plant Nutrition and Nutrient Management
- Oklahoma State University - Electrical Conductivity and pH Guide for Hydroponics
- Texas A&M Agrilife - Essential Nutrients for Plants