Ask the Doc: Diagnosing Nutrient Deficiencies
If your plant’s not growing the way it's supposed to be - if it looks weird - and you assume you have a nutrient deficiency, the first thing you want to do is make sure that the pH is okay. If the pH is too high or too low what happens is the nutrients are actually in the soil, or the solution if you're growing hydroponically, but they're not able to be absorbed by the plants and so if you just keep adding more and more nutrients that's not going to fix the problem because the nutrients are there the plants can't absorb them. And you can actually create toxic levels of nutrients and the nutrients interact with each other so by adding more and more of a nutrient that can actually cause the second nutrient so then bind with it and then you'll have a second deficiency as well. So first make sure the pH is in the appropriate range.
Once the pH is okay you want to look where on the plant you're seeing the problem. If you notice that it's the lower leaves that are yellowing or having problems, that means you have a mobile nutrient deficiency. Certain nutrients are mobile. What that means is they can move around in the plant. Nutrients like nitrogen, phosphorus, potassium, magnesium, and zinc. These are mobile nutrients. So when you see problems in the lower leaves, that's a mobile nutrient deficiency.
If you notice that it's the new leaves that are showing problems, that is an immobile nutrient deficiency. So things like silicon, copper, and iron. These are immobile nutrients and so that's what you might want to consider if you notice that the newer leaves are showing the problems. Now boron and calcium are also immobile nutrients. And they're needed where plants are growing a lot at the very tippy top here. So you might notice that the apical meristem, or the buds of the plant, aren't growing properly that would suggest it's a boron or a calcium deficiency. So if you think you have a nutrient deficiency, check the pH. Maybe the nutrients are available in the solution, the plant just can't absorb them. If the pH is okay, then look on the plant where they're occurring. Lower leaves means you have a mobile nutrient deficiency. If it's the new leaves, or the buds, that means you're going to have an immobile nutrient deficiency. Once you figure out what type of deficiency it is, look at your fertilizer and see if it's lacking any of these nutrients. When you add that nutrient to your solution, you should fix the problem! If you're looking for more information check out htgupply.com/informationcenter and of course there's lots of videos on Instagram TV and YouTube. Thanks for watching. Good growing!