Why Are Your Cannabis Leaves Turning Yellow?
Are some or all of your cannabis leaves turning yellow? Maybe your leaves also have other symptoms like spots, curling, wilting, brown patches and/or more. Marijuana plants may get yellowing leaves for several different reasons, so it can be hard to figure out the true root of the problem
1.) PH is Too High or Low at the Roots
Whether you’re growing in soil, coco coir or in hydroponics, probably the most common reason to see yellowing and other nutrient deficiencies is the pH near the roots is too high or too low. Cannabis plants have a difficult time absorbing nutrients when the pH is off, resulting in nutrient deficiencies even if the nutrients are actually there near the roots.
Yellow or other oddly colored leaves
Spots, stripes or patches
Burning around the edges of leaves
In fact, basically any nutrient deficiency can be triggered by incorrect pH!
Example of a cannabis plant that has a nutrient deficiency and yellowing leaves caused by the pH being off
How Do Growers Get It?
Growers who don’t make sure their pH stays in the right range will often run into nutrient deficiencies, even if they’re starting with a pure source of water and good soil!
Soil Optimum: 6-7 pH
Coco / Hydro Optimum: 5.5-6.5 pH
How to Fix
Use a kit or PH Pen to test the pH of water before you give it to your plants, and adjust if necessary by adding an acid or base to your water
Learn How to Fix Incorrect pH
These symptoms look like nutrient deficiencies, but are actually caused by incorrect pH!
The leaf edges and tips turn bright yellow during a cannabis copper deficiency
Example of a zinc deficiency caused by incorrect pH at the roots
This pot plant is showing the signs of a sulphur deficiency (odd yellowing of leaves starting from the center)This marijuana plant appears to have a potassium deficiency (odd yellowing of leaves starting from the edges) which can look like nutrient burn but is actually caused by incorrect pH
A young cannabis plant with the yellow leaves of a potassium deficiency
This is a deficiency, even though it looks a little like nutrient burn (too high levels of nutrients). The main clue is the yellow striping on the leaves. Another clue is the brown tips are going in further than typical nutrient burn.
The brown edges and tips of these leaves, along with the yellow margins are signs of a cannabis potassium deficiency
Stripes on the leaves (click for close-up) indicates that this isn’t a Nitrogen deficiency, even though the symptoms are somewhat similar. In this case the symptoms were caused by the pH being way too high.
The yellow “striping” on the bottom of the plant is one of the biggest signs that this nutrient deficiency with yellow leaves is caused by a pH problem
2.) Poor Watering Practices
It’s much more common to over-water than under-water cannabis plants, and the symptoms are very similar. Yet in either case the solution is to learn how to water your plants exactly the right amount at the right time!
Symptoms of Poor Watering Practices
Water dripping from a faucet animation - the amount of water (and frequency of watering) have a huge impact on your cannabis plants!Droopiness (it’s normal for plants to droop a little before the lights go out, but you know the drooping is a problem if it’s already happening at the beginning of their “day”)
Odd problems and symptoms from poor water practices including yellowing and sometimes other deficiencies
Overwatering - leaves seem “fat” and swollen with water. Often you’ll have a feeling you may be overwatering your plant, especially if it’s a small plant in a large container
Under-watering - leaves often seem “papery” and thin because they don’t have any water inside them. Chronic under-wateringl leads to overall yellowing and deficiencies.
How Do Growers Get It?
Overwatering is most common with young plants since they still have small, weak root systems
You can hurt plants by giving too much or too little water at a time, and you can also cause persistent droopiness by watering too often or too infrequently
Bad soil with poor drainage can cause the symptoms of overwatering even if you’re watering the plants perfectly!
Small plants in big containers are easily over-watered
Big plants in small containers are easily under-watered
Growers who spend long periods away from their plants and/or don’t pay attention to their watering needs are much more likely to run into problems with droopiness!
Example of a watering can for your garden - the amount and frequency of watering spells the difference between healthy and unhealthy plants!
How to Water Your Plants Correctly
Start with good soil or coco coir
Make sure plants are in the right size container for their size
If plants start drooping after you water them, you’re overwatering!
If drooping plants perk up after watering, you’re under-watering!
Learn how to water your plants perfectly every time!
Overwatered marijuana plant - pot is too big Over-watered cannabis seedling has turned almost completely yellow
Droopy seedling was overwatered in a too-big container, so the roots are having trouble getting the oxygen they need to grow Droopy seedling was overwatered in a too-big container, so the roots are having trouble getting the oxygen they need to grow
Chronic overwatering can sometimes cause unusual deficiencies even if the pH is spot on, like this plant grown in muddy soil. The biggest sign that these symptoms are caused by overwatering and not pH (or something else) is that the plant is always droopy.
This apparent cannabis potassium deficiency looks like a pH problem, but it’s actually been caused by overwatering
Another example of a deficiency that’s actually caused by overwatering (notice how this seedling is also droopy)
Another example of a deficiency caused by overwatering
Chronic Under-watering (Relatively Rare)
Most growers tend to overwater - not underwater - their plants. However, if you’re spending long periods away from your plants or the containers are drying up in less than a day or two, it may mean that your plant needs to be watered more often, or be given more water at a time. It’s also common to under-water when plants start overgrowing their pots.
It can be difficult to diagnose chronic under-watering because problems may look like nutrient deficiencies. Your main clue is that plants perk up every time after you water.
Chronic under-watering can cause cannabis leaves to turn pale and for leaves to turn yellow
I hope this helps