Michelle is a storyteller who is passionate about growing.
EC (electrical conductivity) is an essential measurement of the total amount of food or nutrients available to your plants. EC is really important, as it communicates with you if your plants are receiving the correct amount of food.
Therefore, if your plant has an incorrect EC level, it may start to show signs of stress. Too high, and the plant will show signs of toxicity, too low and the plant will have a nutrient deficiency.
It's helpful to know that plants can only absorb nutrients when they’re in ionic form. When nutrients dissolve in water, they split into ions which carry an electrical charge and the potential for electricity to move through the solution. If we look at pure water—RO, or reverse osmosis water—as an example, it would be a poor conductor of electricity, as it doesn’t contain any ions. The more ions there are, the more electricity it conducts.
So, the more nutrients that are in the water, the higher the EC. This is good news because that gives us a level of control. We can visually check the plants for signs of stress (incorrect EC), measure the EC level using a meter, then correct it by adding more nutrients.
Common scales for measuring EC
- EC (Electrical Conductivity) [1 mS/cm = 1 EC]
- PPM (Parts per Million) [EC x 700]
- TDS (Total Dissolved Solids) or DS (Dissolved Salts) or MS (Measured Salts); otherwise known as PPM 500 [EC x 500]
- CF (Conductivity Factor) [EC x 10]
It is important to note that your EC measurement only displays the complete amount of nutrients available to your plants. It will not show you the breakdown of each available nutrient or nutrient imbalances. You could have the perfect EC measurement, however there may still be nutrient deficiencies.
Preferred EC ranges for some of the most common crop types
A common mistake made with growers can be to feed your plants as much as possible to ensure there is plenty of nutrients available. This can however have major repercussions. Plants have a preferred conductivity range in order to achieve optimal health.
The chart below provides a guide on preferred EC ranges for some of the most common crop types.
How to identify your plants are struggling with incorrect EC (and not something else)
As mentioned above, in order for plants to thrive, it’s required they fall within the preferred EC ranges. If your crops sit outside these measurements for a period of time, they will start to demonstrate symptoms of poor plant health.
It can be difficult to diagnose problems with plants as they could be suffering with incorrect nutrient levels, affected by pests or it is the pH levels being too high or low that is preventing the uptake of nutrients. So even if the EC levels are within range as presented in the preferred EC range chart, it’s crucial to consider it could be some other factor that’s causing the plants to show symptoms of poor health.
Discover the most common nutrient deficiencies in plants and how to fix them to ensure you identify and isolate the problem. It is possible there are various deficiencies and toxicities that could be occurring at the same time.
What causes incorrect EC in plants?
Incorrect EC can be caused by the levels being either too low or too high. If your EC in plants is low, your crops will not be able to receive enough nutrients.
Symptoms when your EC is too low:
- Discolour in leaves (yellow or brown)
- Brown spots of necrosis, or holes in leaves
- Stunted roots, leaves and growth
- Twisted or disproportion of leaves
- Difference in crop yield
If your EC is too high, this can cause salt burn and nutrient toxicity.
Symptoms when your EC is too high:
- Leaf discolouration
- Thickened roots
- Necrosis (when the cells or tissues degenerate) will show brown spots and wilting in leaves and stems. Necrosis will weaken plants and make it more susceptible to other diseases and pests
- Nutrient or salt burn will show bent leaf tips and burnt edges. This will eventually lead to twisting or curling of the leaves if untreated
- Dull appearance on previously shiny leaves
- Slowing down of plant growth
Why measuring EC is vital for plant health
Measuring your EC is vital as you get a closer look at what is occurring within your nutrient feed.
Prevention versus treating is the ideal course of action, and it is likely your EC will fluctuate over time, which is why it’s important to test your EC regularly. No matter what medium you are growing in, staying on top of measuring your EC will ensure issues can be identified and resolved early.
What to expect when EC measurements fall under the following:
- EC measurement stays the same: There is a balanced amount of water and nutrient, keep this consistency by topping up the nutrient tank with the solution of the same strength and check regularly.
- EC measurement is low: There are more nutrients being used up compared to water. Balance this measurement by topping up nutrient solution, or try a stronger nutrient solution feed. Learn more about increasing your EC when it’s measuring too low.
- EC measurement is high: There is more water being used up compared to nutrients. Add water to dilute the solution and balance out the measurement. Burnt leaf tips and slow growth are certain signs of your nutrient solution being too strong. Be aware of weather temperatures also, as plants will take up more water on hotter days. Learn more about lowering your EC when it’s measuring too high.
In hydroponics, you can add more (pH-balanced) water to your reservoir. This will dilute the concentration of salts and lower your EC.
In soil, the same applies where you will need to dilute the concentration of salts by adding pH-balanced water in growing pots or containers until fully saturated and drained.
Creating the optimum EC measurement isn’t only about adding or subtracting nutrients or water. It is recommended to change your nutrient solution regularly, to avoid putting your plants at risk of toxic nutrient levels. Measure EC daily, top up nutrients when necessary, and give your nutrients a refresh by emptying your tank when needed.
How to measure EC in plants
The best way to measure the conductivity (EC) of your plants is with a handheld conductivity pen. This is a robust handheld solution for measuring conductivity and temperature on the go. The Bluelab Truncheon is another favourite for growers.
To take care of the fundamentals, the Bluelab Combo Meter is the ideal device to measure the essential parameters of pH, conductivity and temperature. These fundamentals all play an important role in driving optimal plant health. Learn more about measuring and adjusting your fundamental parameters, as well the four plant health checks you should be doing every day to ensure you’re preventing health issues for your plants.
To learn more about plant growing and how to ensure optimal health for your crops, here are some helpful articles which will help you with all of your growing questions.
- Signs that your plants are struggling with incorrect pH
- pH and EC issues still a problem in some greenhouses
- 7 tips for a successful hydroponic growing operation