Learn Why Leaves Curling Up on Edges in Cannabis Plants

Good day, cannabis cultivators!  As your friendly neighborhood cannabis grower, I’ve had my fair share of head-scratching moments, and believe me, cannabis leaves curling up on the edges rank up there. It’s like the plant’s sending us a distress signal in Morse code, and we’re scrambling to understand what’s going wrong. Is it too hot, too cold,…

Learn Why Leaves Curling Up on Edges in Cannabis Plants

Common Causes of Leaf Curling

Before you pull your hair out in frustration (and we don’t want that), know that cannabis leaf curling can be due to various reasons.

  • Overwatering or underwatering
  • Excessive temperatures
  • Humidity extremes
  • Pests and diseases
  • Nutrient deficiencies

Each of these issues is like a pebble thrown in the serene pond of your plant’s growth journey, causing ripples of trouble.

Overwatering and Underwatering

Overwatering and Underwatering

Watering plants isn’t rocket science, but it’s also not as simple as pouring a glass of water. 

Too little, your plants will look like they’ve been on a desert trek. 

Too much, and they’re practically drowning. 

Overwatering and underwatering can both lead to leaves curling up. 

It’s like the plant’s showing its displeasure by folding its arms… or, in this case, curling its leaves.

Temperature and Humidity Stress

If your plant could speak, it would tell you it isn’t fond of saunas or ice baths. 

Excessive heat, cold, and humidity swings can stress out your plant, leading to the dreaded leaf curl. 

It’s the plant equivalent of a bad hair day due to humidity.

Root Problems

While you admire the lush green foliage above, a whole saga unfolds beneath the soil. 

Root problems such as root-bound plants, root rot, and nutrient deficiencies can result in leaf curling. 

If only plants had a plant psychologist to unload their root-level issues!

Pests and Diseases

Remember how in the old cartoons, the bad guys would always tie up the hero, and they would squirm and twist to escape? 

Well, imagine spider mites, aphids and viruses as the villains of our story, causing your cannabis leaves to curl and twist in distress.

Pests and Diseases

Troubleshooting and Solutions

Unraveling the mystery of curling leaves can feel like defusing a bomb, but with patience and a keen eye, we can restore peace in our cannabis kingdom.

Adjusting Watering Practices

Watering is a delicate dance, folks. 

It would be best not to soak your plants like you’re prepping for a mud wrestling contest. 

On the other hand, letting them dry out isn’t an option either. 

It’s all about balance. Watch your plants. They’ll tell you when they’re thirsty.

Temperature and Humidity Control

If you think maintaining the proper humidity and temperature levels is as tough as wrestling a kangaroo, think again. 

A decent inline fan, good ventilation, and some common sense can do wonders. 

Remember, your plants aren’t preparing for the Olympics. 

No need to make them endure extreme conditions.

Addressing Root Issues

Addressing Root Issues

Imagine being stuck in a tight spot with no room to move. 

That’s your plant when it’s root-bound. 

Or consider not being able to eat because your food’s not right. 

That’s your plant with nutrient deficiencies. 

Adjusting nutrient delivery, transplanting, or changing the medium can help.

Pest Management

Aphids, mites, and other pests can be a menace. 

They’re like playground bullies, causing your leaves to curl up in distress. 

Use organic pest control methods to show these pests who’s boss.

Preventing Leaf Curling

Prevention, as they say, is better than cure. 

Maintaining a balanced nutrient regimen, ensuring adequate airflow, and regularly monitoring plant health can go a long way in keeping leaf curling at bay.

Case Study: Diagnosing Leaf Curling

Let’s talk about our friend’s case in more detail. 

They’ve got a Northern Lights strain, growing in a cozy grow tent, bathed in the glow of a 250W HID light. 

All three of their plants germinated in rockwool and then moved into 4-gallon smart pots filled with a peat moss and perlite mix. 

All good so far, right?

But then we hit a snag. 

Despite maintaining a regular nutrient schedule with the reputable Fox Farms Nutrient Trio, one of the three plants started showing signs of rebellion. 

Leaf curling began to surface, and that’s when our friend knew Houston, we have a problem!

Observing the Symptoms

First, the leaves on the troublemaker were curling up on the edges, while the rest of the plant seemed perfectly happy. 

A classic case of ‘one bad apple.’ 

The curling was accompanied by no significant change in leaf color, ruling out a sudden nitrogen deficiency.

Measuring Humidity and Temperature

Our grower was no newbie and promptly checked the environmental conditions. 

Humidity in the grow tent was at 65%, a significant increase from the house’s regular 45% humidity. 

Although not mentioned explicitly, the temperature is within the acceptable range considering the grower’s experience.

Measuring Humidity and Temperature

Nutrients and pH Levels

Moving on to the nutrients, the Fox Farms Nutrient Trio was being administered according to the dosing schedule, albeit at half doses for the first week. 

This rules out the nutrient burn, another common cause of leaf curling. 

The water pH was consistently between 6.5-6.6, and the runoff post-watering was between 6.4-6.6, within the perfect range for cannabis plants.

Inspecting for Pests

Pests can be secret agents of chaos, so our friend promptly inspected the plant for any signs of infestation. 

Luckily, there was no evidence of aphids, mites, or other common cannabis plant pests.

The Diagnosis

After ruling out the common causes, the evidence pointed toward two possible culprits. 

Firstly, it could be due to a hot spot from the HID grow light

Intense, focused light can cause localized stress, leading to curling leaves. 

Secondly, the increase in tent humidity compared to the rest of the house could have caused some leaf curling. 

The plant might be acting like Goldilocks, and this environment could be just a bit too moist for its liking!

The Action Plan

The Action Plan

To counter the leaf curling, our friend repositioned the grow light, ensuring it was at an adequate distance to avoid hot spots. 

They decided to improve the tent’s ventilation and air movement for humidity, using the 4″ inline fan more effectively. 

The plan was to keep a closer eye on the environmental conditions and make necessary adjustments to create the perfect environment for the Northern Lights to shine!


Why are my leaves curling up on the edges?

Leaf curling can be due to various reasons, such as overwatering, underwatering, excessive temperatures, humidity extremes, pests, diseases, or nutrient deficiencies.

How do you fix curling leaves on plants?

To fix curling leaves, identify and correct the cause, such as improper watering, uncontrolled temperature/humidity, root issues, or pests.

What deficiency causes curling of leaves?

Nutrient deficiencies, particularly nitrogen deficiency, can cause curling of leaves in cannabis plants. 

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