FREE Shipping on Orders 200$ Above
Leaves Turning Yellow During Flowering

When leaves turn yellow during flowering, most cannabis growers feel quite panicking. The meaning behind discoloration on leaves comes for many different reasons. 

It can be due to nutritional deficiency, burning because of excessive light, or just a sign of process called flushing. Does it have a yellow leaves sign that the plants are growing unwell? Are they dying? 

Leaves are turning yellow during flowering means they are just trying to show something. It has many possible reasons. Cannabis growers usually fix the issues with their own. They do not see the yellow leaves as a warning, but they see it as ways of communication from plants. 

Why Leaves Turning Yellow During Flowering

The usual reason leaves turning yellow during flowering is due to stress. Other reasons may be because of excessive heat, poor watering, and pests. Having yellow leaves is usually the sign of unwell cannabis plants that need to be addressed immediately. 

The cannabis leaves were made from different plant cells. Plant cells are made from a specialized organ cell called the chloroplasts. The chloroplast has coloring material that holds a different perception of light. Most of the pigments have green chlorophyll, and those yellow or orange leaves are hidden under the ruling chlorophyll.

The following are reasons why cannabis leaves turn yellow while flowering and some tips on how to make the leaves green again.

Poor Watering Operation

Take a look at the watering schedule of your plant. One of the most common reasons for having yellow leaves is either overwatering or under-watering. You may notice the overwatered plant because it has leaves that seem to be inflated and bowed. 

On the other hand, under-watered plants will grow thin and weak. You may also check the drainage as it can be the reason for overwatering your plant. Always grow your cannabis into pots with holes as drainage in it. The solution with this case is by learning how to water your plants with the right amount and time.

Light Burn

If the yellowing of leaves happens on the top of the plant or nearest where the light source came, your cannabis plants are likely enduring light burn. 

Other symptoms of light burn include the yellow leaves do not easily pull out even if the whole leaf seems to be dead. Light burn usually happens after a few weeks of developing or within the past 6th weeks of the flowering stage. 

Light burn affects the top part leaves instead of affecting the whole plant. If the light burn is already happening, distance your light source from the tops of the cannabis plants. 

Once the leaves become normal, slowly move the light source towards the canopy. Keep it a few centimeters away to prevent the symptoms from happening again.

PH Problems

The pH (potential of Hydrogen) is a measurement scale ranging from 1 to 14. Having a measure from 1 to 16 means acidity, 7 means neutrals, and 8 to 14 means alkalinity. 

Marijuana plants consume nutrients only when the soil is slightly acidic pH. If you use a medium that is too alkaline or acidic, your cannabis plant starts to become deprived. The nutrients deficiencies that will happen to uphold the fan leaves make it turn yellow. 

The only way to resolve it will test your soil first. The sample of the soil will be sent into the lab for a certain reading. You may also try doing reliable tests in your home. 

You may purchase a PH kit then follow the steps to see the accurate results. However, using home kits does not test the presence of calcium carbonate or the soil’s alkaline substance. To help you detect the alkaline substance, get a sample of soil into one cup of vinegar. 

If it fizzes, then it only means the presence of calcium carbonate. If the test resulted in too low PH, the remedy is to add wood ash and lime into the soil. Otherwise, if the result happens is very high, adding sulfur acid to the soil is recommended, which will change the pH of the soil and ensure a successful future harvest.


If the yellow leaves have small spots and bite marks, your plant will probably be infested by pests. Pests are one of the most difficult conditions to handle. 

So, it is ideal for preventing it earlier. Avoid bringing plants from outside into your growing room. You may also try to prevent growing directly from outdoors. 

Before entering your growing room, always wash your hands first, cover your hair, and prevent pets near your growing room. The most common pests in cannabis gardens are the fungus gnats, which commonly live under the wet soil or roots. 

The ideal method to get rid of fungus gnats is by limiting the watering. It may prevent the fungus gnats from laying their eggs from the soil. You can also water your cannabis plants from the top inch of soil to dry it.

Lack of Nutrients

If the leaves from the base part of the plant turn into yellow, the possible problem will be a lack of nutrients. Some nutrients deficiencies include:

  1. Nitrogen
  2. Calcium
  3. Potassium
  4. Sulfur
  5. Iron
  6. Zinc

Nutrient Deficiencies are the most common nutrient deficiencies in cannabis. Excessive nitrogen may cause yellowing of the leaves. Especially the mature leaves at the base of the cannabis plant. 

Other symptoms of nutrient deficiency include lessening the bud sites during the early flowering period. Calcium in the cannabis plant is responsible for securing the cell walls. 

Calcium deficiency includes distorted plant growth on the new structures such as young foliage and root tips. If this deficiency happens in your plant, the leaves will not entirely turn yellow.

Potassium deficiencies are one of the most critical macronutrients in cannabis plants. Having yellow leaves is one of the most common signs of potassium deficiency, which can be the reason why your plants grow curling and dry leaves. If your plant grows into a stunted plant and the leaves turn yellow, your plants will experience a sulfur deficiency. 

Iron is considered to be the major building blocks of plant molecules. Iron acts as one of the energy-giving plants. If the young leaves happen to be the first to turn yellow, your plants have an iron deficiency. The veins of the plants begin to turn yellow and can spread to other older leaves.

Zinc deficiencies make the leaves turn into distorted and yellow in appearance. It can also affect hormonal growth and internode length. The remedies to cure the nutrients deficiencies includes checking the soil PH. 

Cannabis growers may fix the yellowing of the leaves commonly caused by nutrient deficiencies. You can add needed nutrients or fertilizers to the soil. There are available products that you can use to add nutrients to the soil readily. You may also use an organic matter to give your plant long term remedies in nutrients deficiency. 


Having leaves turning yellow during flowering is not a bad sign. You must learn how to handle it by reading some remedies and reasons why leaves turn into yellow. Growing your cannabis plant is very rewarding but sometimes gives you worries too. Try those following steps to prevent your cannabis leaves from turning yellow.

We will inform you when the product arrives in stock. Please leave your valid email address below.

What are you looking for in MJSeedsCanada?

× How can I help you?