How To Fix Clawed Cannabis Leaves
Have any of your marijuana plants ever been hit by "The Claw?" You know, when your marijuana leaves look like the leaf pictured here?
These talon-like leaves will curl and get discolored over time in addition to reducing your plant's growth until the problem is fixed.
Many growers believe that The Claw is caused by pH problems, watering troubles, or heat. What I've learned is that these aren't usually the real cause of clawed marijuana leaves that look like the pictures above.
Downward drooping of leaves is known as "epinasty" in the plant world, and it is true that overwatering can cause similar symptoms... but there is a crucial difference between the type of claw leaf pictured above and the kind that's caused by overwatering.
Today I'm going to explain exactly why growers think that “The Claw” is caused by pH problems, over or underwatering, and too much heat... and I'll reveal why they're usually wrong.
Then I'm going uncover the real reasons why claw leaves happen!
Ok, it's true that overwatering can sometimes cause symptoms that are similar to The Claw. But you won't see The Claw appear out of nowhere on an otherwise healthy plant like the leaves pictured above.
When you do get claw-like symptoms by overwatering, you'll see a progression like what's pictured below.
At first leaves that are overwatered look kind of fat and droopy...almost plump. You won't see just the tips turn down. Here's the first stage of overwatering.
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
- Marijuana plants that get too much Nitrogen in the vegetative stage don't grow as vigorously.
- Too much nitrogen is especially harmful in the flowering stage, because this will cause your plant to produce much smaller buds.
- If you react quickly and reduce your nitrogen levels at the first sign of toxicity, your plant will quickly recover.
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
- Dark green leaves and foliage
- Leaf tips turn down, without signs of overwatering
- You may notice yellowing on the affected leaves or other signs of nutrient deficiencies as time goes on
- Nitrogen toxicity is often but not always accompanied by nutrient burn
- The Claw often seems random, affecting leaves here and there
- Heat and pH problems will make the clawing worse, as they stress out the plant and lower her defenses, and cause her to drink more water (and uptake more N)
- As time goes on, the claw leaves will eventually start turning yellow, getting spots, and dying
Light and "The Claw"
- The distance between the leaves to the lights or irregular light patterns from reflectors often seem to affect the condition, which is why many growers believe that light is somehow causing the problem.
- You may notice this clawing first appears on dark green leaves that aren't getting enough light (they aren't able to use up all their nitrogen and become nitrogen toxic).
The Claw in the Flowering Stage
- If you use vegetative plant nutrients during the flowering stage, then they'll deliver too much nitrogen. This is why you need to get special nutrients meant for the blooming / flowering stage. You'll notice that flowering nutrients always contain a smaller percentage of nitrogen (the first number) compared to nutrients for the vegetative stage.
- Many growers mistakenly keep raising nutrient levels or adding additional nitrogen when they see yellow leaves in the flowering stage, not realizing that it's natural for plant leaves to start yellowing as harvest approaches. Adding too much nitrogen in the flowering stage can cause nitrogen toxicity even when you can see yellow lower leaves. Nitrogen toxicity in flowering results in smaller yields and airy cannabis buds, so make sure to watch out!
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!
What Nutrients Do I Need
to Grow Cannabis?
Do you need special fertilizer to grow weed? How do you choose good marijuana nutrients? Adding cannabis nutrients to your grow can help you get the best potency, yields and growth from your plants. Cannabis plants have two stages of life and they need the right nutrients at the right time.
What special nutrients do I need to grow cannabis?
- Use a “Grow” (high N) nutrient formula for the vegetative stage (the first life stage for cannabis plants)
- Use a “Bloom” (low N) nutrient formula for the flowering stage (when buds are forming) - in a pinch, nutrients for cactus or succulents can be used until you get better nutrients because they have similar nutrient ratios.
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).
Looking for suggestions?