Yellow cannabis leaves, why does it happen?

Written by on 13 January, 2022

Sometimes in cannabis growing, things do not go as expected, so you have to be prepared to deal with any situation. One of the most effective ways is to be aware of the symptoms your plants have, so it’s easier to determine how to act.

Yellowish leaves on your cannabis plants, are often one of the most common signs that something is wrong with your growing, but why is this?

The reasons why cannabis leaves can turn yellow can be several, in this post, we will tell you some of the most common reasons.

1- pH problems

In order to absorb nutrients optimally, cannabis must have an adequate pH, otherwise it will be difficult for it to absorb nutrients, which will result in nutritional deficiencies. The symptoms that will manifest themselves are precisely yellow leaves, spots and burnt leaf edges.

The ideal soil should have a pH between 6 and 7, if you do not get your plants can suffer the damage that we mentioned above.

What can be the solution?

One way to solve this problem is to invest in a pH meter or look for cannabis fertilizers with solutions for a perfect pH.

You can start a root wash with clean water and restart the fertilization with a solution that suits your growing medium. Make sure the fertilizers you use have all the essential microelements.

2- Excess watering

Overwatering is often one of the most common errors, especially in beginner growers. The desire to satisfy your plant’s thirst can lead you to exaggerate with water and end up drowning it. In addition, overwatering causes the soil to become saturated, leading to a reduction in oxygen, which can starve the roots.

All of the above-mentioned drawbacks will make it more difficult for plants to absorb the nutrients they need to develop. This mineral deficiency will trigger the yellowing of the leaves.

What should you do?

One simple way is to try to water your cannabis less. It is also recommended to allow the top 2.5cm of soil to dry out before watering your plants again. You can check this by sticking your fingers in the ground or using a stick.

3- Lack of watering

Sometimes for fear of drowning your plants, you end up making another mistake, which is the lack of watering, this is another cause, why the leaves turn yellow, since water is vital to create energy during photosynthesis, in addition, your plants absorb and transport this liquid throughout.

In addition to the yellow leaves, your plants will begin to bend, and eventually die.

How can you solve it?

The answer is simple: water your plants more. You can apply the above recommendation. Let the top 2.5cm of soil dry out, when you check it, water again.

4- Light burns

When you grow your plants indoors under artificial light, when they are too close to the light bulbs or exposed to too much light, it can cause yellow leaves on your cannabis. This yellow colour will be most noticeable on the top of your plants, which is precisely where the light is most intense.


This type of burn is more common when using very powerful lighting systems. The best thing to do is to move the affected plants away and find out how far away from the light you need to place your plants.

When should you not worry about yellow leaves?

Yellow leaves do not always mean that something is wrong; sometimes it is due to a natural phenomenon. The youngest leaves on the underside of your cannabis, which are close to maturity, will turn yellow and die, but don’t be alarmed, almost all fan leaves will start to turn yellow as harvest time approaches. During this period, applying a root wash will help remove residual nutrients from the environment.

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