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How to Prevent Nutrient Deficiencies in the Flowering Stage

Cannabis Flowering Deficiency

Cannabis plants are resilient when they are in the vegetative phase. However, as the flowering stage progresses, plants stop producing new leaves and instead concentrate on buds. Plants stop replacing leaves after they have worked long and hard hours. Sick or discolored leaves persist until harvest, and if the issue is not corrected, those leaves end up dying, and the problem expands to new parts of the plant. What appears to be a minor issue during the vegetative phase can gradually take over your entire plant during the flowering stage. However, cannabis plants are more delicate when they are producing buds.

Maintaining the ideal environment for the plants, as with most crops, is an essential component for growers. Whether cannabis or cabbage, all plants require a specific combination of sunlight, water, and nutrients to produce high-quality buds. A nutrient deficiency caused by an imbalance in the sensitive ratio of these critical elements can sicken your plants, decrease yields, or even kill your entire batch. Typically, preventing nutrient deficiencies in cannabis begins with recognizing and identifying the problem and having the knowledge to fix it.

Ways to detect and mitigate cannabis nutrients deficiencies in the flowering phase

The most significant cause of flowering stage deficiencies is incorrect pH. However, many other aspects, including a poor environment or improper plant care, can substantially contribute to flowering stage leaf issues.

Flowering cannabis outdoors
Purple cannabis flowering outdoors.

Now, let’s look at some ways of preventing a cannabis flowering deficiency.

Cannabis plant care

Plant care is the routine attention you offer your cannabis plants.  


The most frequent cause of nutrient deficiencies is incorrect pH at the root system. Since each nutrient takes a distinct chemical form based on the pH, and some forms are easier for the roots to absorb than others, the pH affects how well the roots absorb nutrients. During the flowering cannabis stage, plants are often pickier about pH. Even if the plants appeared to be fine without pH adjustment during the vegetative stage, testing the pH should be your first step if you notice nutrient deficiencies during the flowering stage. Moreover, keeping your pH in check is the best way to avoid nutrient deficiencies and ensure your cannabis plants can absorb the nutrients being provided. Evaluate and modify the pH of your water immediately before you give it to crops.

Below are some solutions to improper pH during the flowering phase;

  1. Fill the water with all of the nutrients and supplements.
  2. Using strips, drops, or a pH pen, determine the pH of your water.
  • The pH of soil water should be between 6.0 and 7.0.
  • The pH of coco or hydro water should be between 5.5 and 6.5.
  1. Modify the pH to the desired level – in most cases, use PH Up or PH Down.
  2. Check the pH of the water runoff; if it is significantly higher than what you put in, reduce the pH to the bottom of the range for the next few times watering cannabis. If the pH is considerably lower, provide water at the top of the pH range for the next few waterings.
  3. Repeat.


Photoperiod plants frequently sip less instantly after changing to 12/12. This is because they are suddenly receiving less light per day. As the flowering phase progresses and the plants grow larger, they will begin to drink more again. However, it is easy to overwater the plants if you continue to give the same amount of water instantly after starting the flowering stage. Many farmers are unaware that overwatering (and, in exceptional situations, underwatering) can cause the plant to appear to have nutrient deficiencies. Even if the pH is correct and the nutrients are “there” in the grow medium, deficiencies occur because water isn’t moving correctly in the plant.

How to resolve overwatering

After starting 12/12, pay attention to the wetness of your grow medium. If the soil appears to be wetter than usual, give water less frequently or at a slower rate until the plants are usually sipping again. Droopiness and brown leaf sides are other indications of overwatering.

Depletion of nutrients

In some situations, your grow may experience deficiencies due to nutrient deficiency. Fortunately, it’s easy to tell when plants generally require more nutrients for cannabis. This is common for growers using a “just add water” system, especially if you defoliated your plants or provided enough water to cause runoff. To generate buds, cannabis plants require a lot of nutrients, and they define different signs when they’re running low.

How to correct: This is adding more nutrients to the water in hydroponics or coco. If you’re growing in soil, you can add additional soil nutrients to the water, top-dress with natural and dry provisions, or replant into fresh soil, based on your setup.

Excessive defoliation

The procedure of removing leaves from a plant is known as defoliation. When used tactically during the flowering stage, this method can increase yields, density, and actual bud quality. Many plants, however, stop growing new leaves after a few weeks of growth. Novices should never defoliate a plant until it appears bare in the flowering stage. Since the plant has less of a “buffer” against problems, this can result in stunting and nutrient issues down the road.

How to correct

  • Take care not to remove too many leaves during the flowering stage, particularly after the week.
  • Beginners should never “strip” their plant, especially if they face an issue or nutrient deficiency.

Plant environment

In the flowering stage, your surroundings are far more essential than in the vegetative stage. The environment has a significant impact on your ultimate bud effectiveness and plant health and leaves.


The extent of hotness or coldness tested on a specific scale is temperature. Cannabis plants can’t absorb nutrients properly if the humidity and temperature aren’t just proper. Temperatures influence how thirsty your plant is. High temperatures promote faster water absorption, while low temperatures discourage drinking. The best approach is to strike the proper balance.

How to correct temperature;


  • Increase air circulation by venting hot air from the grow space.
  • If at all possible, reduce the brightness of the light.
  • Consider using smaller or different grow lights that produce less heat 
  • If the room is too hot, use an air conditioner or an evaporative cooler.
  • Set the timer so that the grow lights are turned off during the hottest part of the day.
  • It can’t hurt to have a heat-resistant strain like Soul Diesel and Amnesia Haze.


  • Wrap the grow room or tent in insulation.
  • To raise the temperature of the room, use a heater.
  • Set the electrical timer to turn on the grow lights at night, when it is the coldest.
  • Keep roots away from the cold floor, particularly in a cellar or garage.
  • Auto-flowering strains are a good choice in the winter because grow lights can run up to 24 hours a day, preventing a cold dark period.
  • Choose a photoperiod strain that can withstand cold temperatures, such as Northern Light or Durban Poison.


When the humidity level rises, moisture is taken up by the leaves. Less moisture is absorbed from the atmosphere when it is low, and water is mainly consumed through the roots. Plants use less nutrient supply around the root zone when humidity contents are too high. In addition, nutrient deficiencies and other issues can occur, especially in colder climates, if humidity levels are higher than average. Luckily, you can fix the humidity issue by proper ventilation and using a humidifier or dehumidifier.


If your crops are too near to the light, like LED or HPS grow lights, they may appear “sunburned” even if the temperatures aren’t high. The sunburn appearance caused by the plants being too close to the lights may be a potassium deficiency, but it could be a light burn or even a cannabis nutrient burn.

How to fix overly closed lights:

  • Increase the distance between the lights.
  • Some grow lights allow you to reduce the power.
  • Change to a lower-powered grow light.
Picture of Ed Rushford

Ed Rushford

Ed Rushford’s impact on cannabis growing is undeniable. Though he tends to focus primarily on 2 areas, plant training techniques and dealing with disease, pests, and other problems, he has offered many insights into how cannabis plants live and grow. That’s not to say that Ed is unfamiliar with the complete life cycle of cannabis, from seed to harvest, but he uses his widespread knowledge to hone in on the minutia and niche areas of growing cannabis. Ed’s goal is to spread knowledge and allow for everyone to become better growers. About this Author

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