Lets Talk EC and Cannabis

You might be here because you've heard about EC levels as it relates to cannabis growing. You may also be having problems with your grow and hoping to find out if EC is the culprit. Could be. Let's discuss;


EC or electrical conductivity is a measurement of how much electrical activity is in your soil / substrate at any given time. We know that water can conduct electricity. Well, that's not totally true. Distilled water can't conduct electricity at all. It has been stripped of all minerals. Highly mineralized tap water can conduct electricity like copper wire. Adding nutrients to your soil increases EC. Growing in artificial substrate like rockwool could have a zero EC level depending on how it's made. 

Natural soil has plenty of minerals and when enough water is supplied EC levels can be easily checked using a high quality sensor like the AROYA SOLUS. Retail potting soils have a wide range of minerals which are added during mixing and will have an entirely different EC level when water is added. 

AROYA SOLUS at work 


EC is important because it helps us understand the level of nutrients and fertilizer, in addition to what was already in your chosen grow medium. Too many nutrients will block your plants ability to absorb water through the roots. Symptoms include yellow and brown leaf tips and curling. Not enough nutrients allows the plant to absorb water without the ideal level of nutrition to maximize growth rates. This often shows up as leaves yellowing. 


Most of us have had times when we can't figure out why the plants are struggling. Too much water or not enough? Too much nutrients or not enough? If we wait too long to solve the problem the plants can become permanently stunted. Nothing is more frustrating than having to kill plants because we guessed wrong about the symptoms. 


EC is measured using a tool that measures water content, and what's called water potential in your soil. We'll skip the deep dive to avoid nap time. In a nutshell the EC level is your soil increases as the soil becomes saturated with water. And it decreases as the water drains away. This is because there is less water to conduct the electricity through the minerals. 


Freshly saturated 6 x 6 rockwool blocks (screen grab from AROYA SOLUS App)

All of us care about light levels. Most of us have PAR measurement tools so we know what we're providing to the plants. Tools like the AROYA SOLUS are just as vital as a PAR meter. Seedlings require a different level of EC versus Veg plants versus Flowers. 

Coco, living soil, potting soil, all have different speeds of drying out after a full dousing of water. Fabric pots air out faster than plastic pots and so on. The image above shows a 1.87 EC level 20 minutes after fully saturating a rockwool cube and was 80% water content. The moisture content level will slowly go down as the water drains off, evaporates or the plant takes uses it. The EC level will rise during the run-off phase and between these two variables the ideal EC level can be maintained. 


The Ideal EC level for cannabis seedlings and young veg plants is around 0.5 - 0.8 until around 12 to 14 days after germinating. This should be progressively increased to 1.1 towards the end of the growth period. During flowering stage plants need more nutrients. EC should be between 1.2 and 1.5, keeping it there until the fattening period, where you should increase it to 1.8 / 2.1. It should never be higher. 

Since we know the two are related we also need to keep an eye on moisture content. This is a huge area of study with a lot of different approaches and opinions. It's best to think of moisture content as the controller of EC levels.

To increase EC levels we increase the amount of water with nutrient feed. Decreasing EC is a matter of adding water (ideally with lower nutrient/salt level) which will wash away the larger minerals and nutrients from the soil and reduces EC.

The amount of nutrients depends on the brands you choose, and the desired effects on your plants so we'll leave this for another post. 


We like the AROYA SOLUS because it is easy to use, portable and highly accurate. The App is simple and its easy to understand the readings.

Just like PAR meters, the SOLUS is a spot measurement tool, Personally we don't have the time to crunch data from software. We like simplicity because we'll use it more often. 

For our needs the SOLUS is great. We just take spot measurements as we transition to any new soil medium, nutrient mix or when we change the watering schedule. We know our water minerality isn't going to change much. So it's all about the quantity of water and how fast or slow we apply it and how the nutrients are building up in the soil or washing away. Once we have that nailed down we just take spot measurements occasionally and if we see any negative growth symptoms developing we get right on it with the SOLUS. 



 Every serious grower should own an AROYA SOLUS as well as a good PAR meter like the Apogee MQ-500. These tools are indispensable and will both save crops from accidental mismanagement. The cost is well worth it.  


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