This is the Most Common Sign your Plant Has Something Wrong with it
Well, there is generally only one real answer to this: your plant is not producing enough chlorophyll. The question is why?
Like anything concerning cannabis, there could be several reasons. When I first started growing cannabis, I bought a book called The Cannabis Grow Bible (3rd Edition). One of the chapters of this book was entitled “Problem Solving.” Well, after growing cannabis now for over 15 years, I learned this problem-solving chapter was indeed problematic in its approach. They had illustrations in this chapter of different leaves that looked discolored, and then they had a corresponding reason as to why the plants were experiencing this discoloration. The problem with this guide is this: there are seemingly an infinite number of things that you can screw up when it comes to growing cannabis, but your plants can only show you a handful of stress signals.
Grow Books Are Limited in Their Inherent Nature
First, I want to say that The Cannabis Grow Bible is a good resource and a good place to start if you want to learn how to grow cannabis on your own at home. As far as books go, it’s one of the better ones that I have read. But as I’ve written in another blog post, books are kind of a one-size-fits-all solution to growing. They have a ton of useful content, but it’s really a buffet of information, and the vast majority of the information in the books is not going to pertain to your specific situation.
Appearance is Only Leaf Deep
Oftentimes, this is what I deal with when working with clients: they have some problem, and they think by telling me what their plants look like, I can determine, based on that alone, what is going awry. But that is not how growing cannabis works. Once they tell me how the plant looks, I generally tell them, “Thank you for that, but in order to diagnose what is really going on, I need to know everything the plants are experiencing.” Like any process, there is a lot going on, oftentimes.
Here are Some of the Most Common Reasons for Yellowing of Cannabis Leaves
Nutrient deficiency, usually calcium or magnesium, but could be other micro-nutrients as well.
Nutrient lockout / chemical burn, usually from overfeeding plants.
Photo-stress / photo inhibition. This is generally because the plants are actually receiving too much light.
I’ve experienced yellowing of leaves for all three of these reasons, and other reasons as well, but to keep things simple, let’s just start there, as probably 90% of leaf-yellowing issues fall into one of these three buckets.
So how do you fix these problems?
Nutrient Deficiency
A: This one is pretty straightforward. Somewhere you went wrong when it comes to feeding your plants a healthy diet. And this is very easy to do; most, if not all, cannabis farmers have experienced this to one degree or another. For new growers, I recommend using some bottled nutrients along with an organic medium (soil + organic compost, typically). With bottled nutrients, you generally will get an easy-to-use feeding guide so that you know how to feed your plants, along with recommended pH levels for these formulations.
With bottled nutrients, you can typically “flush” your pots so you can start with a clean slate. Once you flush, you can go back to the correct formula to amend your pots.
When it comes to a more organic farm, this gets more complicated, and the necessary amendments could only be understood by delving into what type of medium and composting methods have been introduced, along with what specific organic techniques are being implemented.
Nutrient Lockout / Chemical Burn, Usually From Overfeeding Plants.
A: This one is even more straightforward. In lay terms, your plants cannot take in any more nutrients because they are locked out due to a concentration of “salts” (caused by sodium dioxide-based bottled nutrients) that accumulate at the bottom of your pots. In this situation, you want to flush even more thoroughly. I recommend flushing twice and then testing the runoff water from the pots for its “parts per million” level, or ppm. The lower that number, the more successful the flush. Then go back to feeding the correct diet.
For organic farms, nutrient lockout is uncommon, as organic methods of farming tend to be more self-regulating and are not sodium-based.
Photo Stress / Photo Inhibition
A. This is one that even veteran growers get wrong because this one is a tad more complicated. As a new grower, you’re green AF, and as a result you’re thinking, “More light, baby!” (George Costanza voice). The problem with that is more light isn’t necessarily going to automatically give you better yields. It’s more about getting just the right amount of light. Think of it as a microcosm of the “Goldilocks Zone”—for my space nerds out there. Like the childhood parable of Goldilocks and the Three Bears, you can’t have it too hot or too cold; you need it just right. The technical terminology here would be lost on anyone but super nerds like myself, so for clarity, let’s say what you want to focus on as a cannabis farmer when it comes to light is getting the right light density for your crop.
Here’s a real-world example. When I was a novice, I ran 12 plants in five-gallon pots under one Fluence LED that runs at around 650 watts. On my next crop, I used the same setup but only put four plants in five-gallon pots under the same light, hoping the plants would carry the extra load and I would just have larger plants I needed to water and feed more often. But I was wrong. The plants, being no larger than the original 12 I used the first run, were far too small to absorb the amount of light that I was putting on them. So the leaves yellowed, and I thought it was one of the two former problems I addressed in this blog post, since I had those problems before and was familiar with them. The 12 plants thrived where the four failed because the 12 were getting “just the right amount” of light. So this will take some trial and error, and some math, so add the correct number of plants or invest in a dimmer and dim your lights to where your plants are more receptive to the amount of light they are receiving.
It’s worth mentioning at this juncture that this is just one example of how hard it can be to even diagnose a problem, let alone how to efficaciously amend it. Even though I feel strongly that I wrote how to amend these problems properly, within all three of these examples there is plenty of wiggle room for nuances. And THAT is where my consultancy shines. I’m experienced in all the nuances, and I can teach you how to work with them, not against them. One Love.
Related Articles:
Beginner Growers Don’t Need More Information – They Need Better Direction (Indoor Cannabis Guide)
How to Prevent Pests in Your Cannabis Grow Before You Even Get Started
Why You should Grow From Seed and Never Buy Clones
Why You Should Grow Your Own Part 2 Customizing Your Grow to Your Needs
Why You Should Grow Your Own Cannabis? Your Health
Why You Should Grow Your Own Cannabis Part 3, Taking Pride in What You Do
