by Alex Robles
Greetings everyone, I hope your gardens are looking lush. Since winter is among us I’m going to keep talking about nutrients, specifically nutrient mobility. I think it’s a good thing to understand because it helps me recognize a nutrient deficiencies quicker. In some past posts I’ve given different examples of how this works. Right now I’d like to go a little deeper into it, but not too deep because there’s a lot more science behind it then what I’m about to mention.
A cannabis plant will take up nutrients and assign them to where they’re needed in different amounts. When we talk about nutrient mobility we’re simply talking about is how easy those nutrients move through the plant. The clearest example I can give is it to think of the leaves as a savings account for nutrients. Every nutrients is deposited into the leaves but not all those nutrients can be withdrawn when they’re needed in other parts of the plant during a deficiency. The ones that can be taken and moved around easily are known as mobile, while the ones that are locked in place are known as immobile.
If a plant is deficient of a mobile element like nitrogen (N), phosphorus (P), potassium (K) or magnesium (Mg), it can be take those elements from the lower, older growth and move them to areas of newer growth where they’re needed the most. When new growth happens during one of these deficiency, the plant will take the nutrients from the older leaves and use them to grow the new leaves. The old leaves are now left without enough of that nutrient and will start to show signs of deficiency. The most obvious symptom will be chlorosis (yellowing or discoloration of the leaves).
When a plant is deficient of an immobile element like calcium (Ca) or sulfur (S) the symptoms will begin in the upper, newer growth. This happens because these nutrients get locked in place or move very slowly through the plant. Since it isn’t getting what it needs from the root zone and it can’t take it from the older leaves, it will put out new growth, the best it can without that nutrient. The most obvious signs of these deficiencies will be slower, stunted growth and chlorosis.
Well I hope this helps you understand nutrient mobility a little better. If you want to get deeper into plant science, Michigan State University has a couple of really good research articles on the subject that are worth reading.
Grow, Learn, Teach