Nitrogen Deficiency in Marijuana

It is normal for your plant to drop some of the older leaves every so often. But if you are losing too many – especially if the plant is small -, if before they fall they become yellow until they completely lose color, and if the yellowing is gradually increasing to higher leaves, then you have a nitrogen deficiency and you will have to solve it. soon as possible.

This is one of the most common deficiencies in marijuana. Nitrogen is an essential nutrient for plant growth and you must supply it from the start using a good soil.

If your plant shows advanced signs during the growth stage — vegetative period — its growth will slow down and it will not be able to develop its full potential.

On the other hand, during the flowering stage the plant no longer needs as much nitrogen and it is normal for it to generate a deficiency while it is forming the buds.

Colors and Symptoms for Nitrogen deficiency

In Older / Lower Leaves

Leaf ColorSymptoms
They start with yellow spots between veinsWith the yellowing their growth slows down
They turn completely yellow and pale yellowThey start to wrinkle and the tips dry
They begin to fall day by day

chart-nitrogen-deficiency-colors-cannabisNitrogen deficiency begins with the tip of the leaf losing color, as it moves it moves inward, leaving it completely pale. The leaf will then start to brown and wrinkle, until it finally falls off the plant.

This symptom begins in the lowest and oldest leaves, if you do not solve it quickly it will “go up” through the plant to increasingly new leaves.

You should keep in mind that once nitrogen deficiency is detected, the plant’s ability to develop has already been affected. In turn, the plant becomes less resistant against pests, cold and disease.

If you keep seeing these symptoms after applying the solutions mentioned below, then it is not nitrogen that your plant is lacking and we must find out what is causing the leaves to turn yellow.

In Newer / Upper Leaves

In newer leaves it can be seen that they do not grow with the same vigor as before, with small and fine leaves. If the deficiency is significant, the petioles — twigs that connect the leaf to the main stem — can turn red or violet.

During Flowering Stage

It’s completely normal for your plant to experience nitrogen deficiency entering or during flowering, as I mentioned in the introduction.

This is a good sign since marijuana needs lower levels of nitrogen as it forms its buds, and too much of it could detract from your harvest significantly.

Flowering fertilizers come with very low nitrogen levels for this very reason.

Nitrogen Deficiency Pictures

How to Fix a Nitrogen Deficiency?

It’s one of the simplest deficiencies to fix, here are a few ways — simple and complex — to fix a nitrogen deficiency. But first I must make some clarifications.

If you have already been using fertilizers, or if you are sure that your soil has sufficient nutrients, it is likely to be an unfavorable pH variation in your substrate or irrigation water. See the section below.

If the leaves that are turning yellow are the newest / tallest or if the stains they show are different from the photos shown, then it is a deficiency of another nutrient or a bigger problem.

Growth Fertilizer

Using a high nitrogen water soluble growth fertilizer is the best way to resolve this deficiency as it goes directly to the roots. They absorb it quickly and in a few days they will recover their original color.

These fertilizers are bought in any nursery, almost any ‘food’ for plants will contain nitrogen.

There are two types, mineral fertilizer and organic fertilizer. The difference is that organic improves the characteristics of the soil by providing nutrients, while minerals contain chemical elements, are absorbed faster and are more precise and cheaper.

Earthworm Humus

The best option for beginners and a very reliable one for everyone. Humus is an organic fertilizer made up of earthworm droppings, which recycle organic material from the soil.

Actually, humus should be mandatory in any cultivator’s land. It provides more than enough nitrogen, as well as other essential nutrients, and helps to maintain and create millions of microorganisms that give life to the earth.

If your substrate does not have humus, or not enough, it can be provided by making a “tea”.

  1. Fill a wide-mouthed container with water and let it sit for at least 24 hours.
  2. For each liter of water add 3-4 tablespoons of earthworm humus and stir well.
  3. Let stand again for 24 hours, stirring every so often.

And ready. Now it only remains to water the plants with our tea for the next few days. The interesting thing about humus is that it does not cause overfertilization, which can happen with purchased fertilizers, so there is no risk for beginners.

Keep in mind that the effects of nitrogen deficiency will take about 7 days to wear off, so be patient.

Diluted Urine

urine-fertilizer-high-nitrogenThe main thing you must to fertilize with urine is that it must be mixed with carbon-rich materials so that it can work and nitrogen is available to your plant. If you have a prepared substrate it should be enough. In case you don’t have it, better to use the earthworm humus solution.

A friend of mine Vicky, an experienced cultivator, does not recommend using it. “You really have to go on a diet a week before … and it’s not a reliable method either.”

For my part I have compiled various sources of gardening and agriculture on the use of urine, and I have tested it on my crops in cases of not being able to buy fertilizer.

The urine contains high levels of nitrogen and its composition (N-P-K 11-1-2.5 approximately) is similar to the fertilizers that you can buy normally.

How to use it:

  1. Pee into a plastic bottle 😛
  2. Dilute it with water, 1 part urine every 10-15 parts water. For example, if you put 1 liter of urine, you dilute in 15 liters of water. In 100 milliliters in 1.5 liters.
  3. Remove a small layer of soil taking care not to damage the roots
    Water with diluted urine as you would normally.
  4. Refill the soil layer.
  5. Water again with plain water (not in excess).

Removing the earth allows you to avoid bad odors and make better use of nitrogen, by achieving less ammonia generation.

Remember that irrigation water should always be left to stand for at least 24 hours to clean it of chlorine and other elements.

Important References:

Blood Meal

blood-meal-nitrogen-fertilizerNot to be confused with ‘Bone meal’ which is used for flowering due to the contribution of phosphorus.

Blood meal is widely used for the cultivation of foodstuffs, provides a high nitrogen content and has excellent properties. You can buy it at any gardening or agriculture store.

I recommend it only for those who are used to fertilizing since it can generate overfertilization very easily.

  1. In a bottle filled to 10% of its capacity with blood meal.
  2. Fill the rest with water that you will have left to rest for at least 24 hours.
  3. Mix well and let stand.
  4. Mix again from time to time and open the lid to let out the gases that are generated.
  5. Wait a few days until there are no solids in the bottle.
  6. You mix the contents of the bottle again with standing water, at the rate of 1 part of solution for every 10 parts of water.

With this new double-diluted solution you can now fertilize your plants.

Be careful not to apply it more than 2 times a week. Speaking of fertilizing, it is said that “less is more”. It is always better to have to apply a little several times, and thus make sure not to overfertilize and affect the roots.

Wrong pH

ph-meter-example
pH Meter

Be suspicious of having the wrong pH if you are sure that your plants have enough nutrients because you provided them with a good substrate and fertilize correctly. Or if you applied the solutions listed above and your plant fails to recover after 7-10 days.

In this case, nitrogen and other nutrients are present and available to your plant, but it cannot absorb it correctly.

Overfertilization is a common cause of pH problems.

Before continuing, you should check that both your soil and the irrigation water have a pH in the range of 5.8 to 6.8.

Thank you for reading

Hopefully you have no pH problems and can easily solve this lack. Throughout January I will continue to upload guides to identify and solve typical deficiencies of the marijuana plant.

The next guide will be about potassium, a much-needed nutrient for flowering and a very common deficiency. And luckily, also easy to fix.

If you want me to notify you when the next guide is published and all that are to come, you can sign up for the mailing list below. I always promise to send you quality content.

Thanks for reading and much success with your crop.

Santiago @ Dr. Cannabis
Santiago @ Dr. Cannabis
I'm here to help out marijuana growers have a greater experience with their plants, and not loose their mind over the many problems and situations that often arise during the different stages of cannabis growth.
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