Leaves Turning Yellow During Flowering | Causes and their Fixes

Leaves Turning Yellow During Flowering

Plants with lush green leaves brighten your day and adorn your surroundings, from the living area to landscapes. Plant leaves, however, can sometimes become yellow and rust brown spots can appear on them despite your constant attempts, these problems can often be fixed by treating or improving the plant medium. As long as you properly and quickly identify the problem and fix it, you can reduce the damage caused by these problem at minimum.

The yellow part, also known as chlorosis, occurs when something interferes with your plant’s chlorophyll, the green pigment that gives it its color. The positive news is that yellow leaves indicate when plants want assistance. Yellow leaves may be remedied and prevented by understanding the signals and taking the appropriate actions. Yellowing leaves are the first clues that your plant is in trouble if you’ve ever been a caring plant owner. 

Is it Normal for Plant Leaves to Turn Yellow During Flowering?

It’s normal for the plant leaves to turn yellow during the last weeks of blossoming. Your plants are merely devoting energy to bud development while allowing the leaves to fall off. This is a positive thing. However, it is likely a major problem if the yellowing appears early in the blooming process (or even before vegging).

It might also be a variety of issues. That is why, before you can solve an issue, you must first identify it. The yellowing of plant leaves is caused by a nitrogen (N) deficiency, a completely natural occurrence in the plants as the plant reaches the end of its life cycle. Plants require less nitrogen (which is more essential at the beginning of flowering) and more phosphorous (P) and potassium during the last weeks of blooming (K).

Possible Causes of Leaves Turning Yellow During Early Flowering 

The gardener looks forward to spring and early summer. Seeds are growing, transplants are establishing themselves, and your effort and time investment in the garden is paying off. You may come across yellow leaves on the plants while going through the garden. The yellowing of the plant leaves indicates that the plant isn’t producing enough chlorophyll. Several factors might cause chlorosis. Pests and diseases might cause yellow leaves, or they can indicate a plant’s natural aging process.

There are the following possible causes of leaves turning yellow during flowering-

1. Light Burn 

leaves turning yellow during flowering

Yellowing is most noticeable in the part of the plant that is closest to the light. Even if the whole leaf withers, the yellow leaf is hard to come off. Mild burns often take several weeks to develop and are most common when the plant is past the sixth week of flowering (when the plant is not producing many new leaves to replace the old ones). 

Burning cannabis light usually affects the upper leaves closest to the growing light rather than affecting the plants evenly. The best way to fix a light burn is to keep the light away or lean against the affected plant and keep it away from the light. If in doubt, always follow the manufacturer’s recommendations if you need to keep the light away from the plants. This is especially important for growers who use LEDs.

2. Insufficient Light 

leaves turning yellow during early flowering insufficient light

Insufficient light might induce yellowing of the leaves. I know; it’s perplexing. The good news is that yellow leaves are only caused by a lack of light early in a plant’s existence. If they change color during blossoming, inadequate light is not the issue; therefore, you can check this one off your list. This is because they are not getting enough light during their growing stage. As a result, ensure that your plants are exposed to high-quality light for the best growth.

3. Inappropriate Temperature 

We have highlighted the potential of your grow lights producing light burn if they are too close to the plants and therefore too hot. Even if the lights aren’t the source of the problem, an excessively hot or cold environment in the grow room might cause leaves to be yellow.

Temperature fluctuations can induce the yellowing of leaves during the flowering period, especially if the temperature falls outside of the ideal range. These temperature ranges must not fall below or exceed these levels. Yellowing of foliage may occur if it decreases or rises for more than a day.

You want to keep the temperature between 60° F and 85° F. It will be cooler at night, but it should never go below 60°. During the day, the temperature should never exceed 85°. Use fans, ventilation ducting, air conditioning systems, grow lights, and heaters to control the temperature. Of course, you won’t require all of those materials. Mini grow tents generally don’t require much more than a grow lamp and a standard fan. Large grow tents will almost certainly need extra heating and cooling equipment.

4. Nutrient Deficiency 

Nitrogen is usually the first nutrient that needs to be mentioned as the cause of yellowing leaves, but that is not the only one. Yellowing of the leaves can also suggest a shortage of other nutrients such as iron, manganese, or zinc in the soil. The pattern of yellowing of the leaf proceeds might provide some hints to which nutrient may be deficient, the most accurate method is to perform a soil test. This will provide an accurate nutritional composition and the required nutrient supplements.

When one or more nutrients (particularly macronutrients) are deficient, the leaves yellow throughout the blooming stage. In addition, an overabundance of nutrients may cause leaves to become yellow, but this is uncommon. Ensure that you supplied your plants with the proper fertilizer scheme and balanced the pH for nutrient uptake to fix the issue.

A magnesium deficiency results in a distinct type of yellowing. Instead of the entire leaf turning color, the veins remain green, and just the areas between the veins become yellow. If your plants aren’t getting enough iron, the newest leaves will turn yellow, not the older ones. This makes it rather simple to diagnose the problem. The leaves begin yellow, then turn green from the outside edges inward.

5. Inappropriate Watering

During the flowering period, both over-watering and under-watering can induce yellowing of the leaves. Overwatering causes root blockage, which reduces oxygen flow around the plant roots. Overwatering can promote the growth of harmful bacteria and diseases.


Overwatering is one of the most common causes of yellowing leaves since it is difficult to determine when to stop watering them. Poke around and softly dig up the dirt to look for this. If it’s wet, it means it’s not draining effectively and is retaining too much water.

If the plant condition is severe, you can add sand or replant. Give your plants less water to solve this problem. However, you must ensure that the problem is not caused by inadequate drainage, and you must also determine if you are using too much water at once or watering too regularly.


Under-watering is far less frequent than over-watering, but it can still happen, particularly if your container is too large for the plant. Because they lack water, the leaves will be thin. It is most likely dehydrated if your plant appears droopy but brightens up immediately after watering.

Underwatering is a little more common cause of yellow leaves since, as humans, we occasionally fail to care for our plants. If this happens too frequently, the leaves may turn yellow and become dry and crunchy to the touch. Get the watering can out as soon as possible and begin watering! Learn about indoor plant care, including disease prevention and treatment.

6. pH imbalance around the root 

leaves yellowing and dying during flowering ph imbalanced around the root

Finally, the most prevalent cause of yellowing leaves is an improper pH in the root region. When the pH is out of range, cannabis roots cannot absorb certain nutrients, resulting in a deficit. While a shortage of a certain nutrient is the immediate cause of the yellow leaves, the fundamental reason is a pH imbalance.

6.8 is the perfect pH for marijuana plants growing in soil. The optimal pH for weed plants growing in water (hydroponics) or other soil-less medium is 5.8. To measure the pH of runoff water, use a pH meter. If the pH is not correct, you should cleanse the root region with neutral water. Then provide the plant with pH-balanced water. pH Up/down solutions can be used to modify it.

Inappropriate pH levels might induce the yellowing of leaves during the blooming period. This issue is addressed by ensuring that the pH of the nutrients does not go outside of the acceptable range. As a result, you must constantly use the appropriate pH meters to check the pH range.

7. Pests 

leaves turning yellow during flowering

A pest infestation can also cause yellow leaves. Even if you have a perfectly sealed grow tent, you can carry bugs in on your shoes or clothing, or there could be eggs on a clone you bring in. An insect infestation can also induce yellowing of the leaves during the blossoming period. That’s why you should make sure your grow tent is well sealed. In addition, be careful to inspect any clones or new plants you bring into your indoor garden for pests.

To determine if your discolored leaves result from a pest infestation, thoroughly inspect your plants and see if you notice any holes on leaves and bugs and crawling around.  Maintain a healthy and hygienic grow place as well. Overwatering or making a mess around your grow space might promote bug infestations.

Summing Up 

Yellowing leaves during flowering is a reason for worry, especially if there are additional signs of an unwell plant. Over- or underwatering, light burn, Inappropriate temperature, and a lack of light are all typical causes of yellowing leaves during flowering. It might also be related to an insect infestation or a vitamin shortage.

While some yellow leaves are acceptable, they might indicate that your plant isn’t receiving enough water, light, or nutrients to grow. These yellow leaves will not regrow, so it’s better to cut them off and examine them and observe what they’re telling you about what it needs to be done. I hope this post was able to answer your query regarding leaves turning yellow during flowering.

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