If the overwatering continues and plant is still unable to get oxygen at her roots, then you may start getting other apparent nutrient problems because the plant isn't getting everything she needs.
If left unchecked, this can eventually cause The Claw.
With the case of overwatering vs. nitrogen toxicity, it can be confusing because these both cause leaves to point downward. Yet if you see the different problems together, you can easily learn how to spot the difference.
Now that you know what an overwatered marijuana plant looks like, let me show you what to look for in a nitrogen toxic plant.
2.) Too Much Nitrogen?
Okay, you ruled out overwatering, now what?
When I first got started growing, everyone kept telling me that this particular kind of leaf clawing was caused by under or overwatering my plants, pH problems, or heat problems.
Yet in my case, I knew that it wasn't over or under watering (I was growing in hydro, where roots grow directly in water and air stones are constantly adding oxygen). I knew it wasn't pH (my reservoir water had the right pH) and I knew it wasn't heat since the grow area was slightly cooler than room temperature.
So then what was really causing my claw leaves?
Now, you may or may not know that marijuana (or any plant) needs an element known as "Nitrogen" to grow.
In fact, nitrogen is one of the 3 nutrients that are included in almost every kind of plant food.
When looking at plant nutrients, you'll almost always see 3 numbers listed, like 3-12-6 or 5-10-5. These numbers represent the ratio of Nitrogen (N), Phosphorous (P) and Potassium (K) contained in the bottle. Just about all plant life on Earth needs these 3 elements to grow.
The very first number, "3" in the case of the picture to the right, always displays the proportion of nitrogen in this nutrient bottle compared to the other 2 nutrients (Phosphorus and Potassium respectively).
The reason nitrogen is in all plant nutrient formulations is because it's vital to plant processes.
For marijuana plants, when they don't get enough nitrogen, the bottom leaves start turning yellow and dying. Left unchecked, a nitrogen deficiency can cause the whole plant to eventually turn yellow and die.
However, this time we're the dealing with the opposite problem: nitrogen toxicity, or too much nitrogen.
Why You Should Treat and Prevent Nitrogen Toxicity
Note: Some strains with the word "Claw" in the name tend to do The Claw more easily than others.
Problems with excess nitrogen are not common in the wild; it's a lot more common to see nitrogen toxicity on indoor plants, especially when overzealous growers go a little overboard with nutrients, or start with "hot" soil.
Occasionally you'll come across a strain or particular plant that likes lower levels of nutrients, and when this happens, it's important to realize the plant is showing signs of toxicity, even if all the other plants in your garden seem fine.
One of the most common signs off too-many-nutrients is "nutrient burn," or when the tips of your leaf appear brown or burned. Yet there are specific signals your plant will display when she's getting too much nitrogen...
How You Know You Have Nitrogen Toxicity
Light and "The Claw"
The Claw in the Flowering Stage
Note: During the last few weeks before harvest, marijuana plants starts pulling all the remaining nitrogen from her leaves as part of the bud-making process. This causes yellowing leaves starting towards the bottom of the plant. This is part of the natural flowering process and you don't need to fight it. You may notice that marijuana leaves are yellowing in almost all pictures of marijuana plants with big buds that are close to harvest. You tend to get smaller yields at harvest from nitrogen-toxic plants with dark green leaves.
It's Normal For Marijuana Leaves To Start Turning Yellow As Harvest Time Approaches, Don't Keep Adding More Nitrogen!
I know a lot of marijuana plant problems can look similar, but now that you're armed with the right information, you'll know exactly what to do if you see Nitrogen Toxicity affecting your marijuana plants.
I hope that the information in today's article helps you as much as it would have helped me when I first started growing!
Note: Don’t use anything with time-released nutrients (like fertilizer spikes, or Miracle-Gro soil - they deliver too much N in the flowering stage).