Nitrogen Deficiency on Marijuana Plants

How to spot it? Is it good or bad? All you answers

Hi there and welcome (back) to Free the Tree!
Today we decided to finally cover Nitrogen deficiency on Cannabis. I’ve been wanting to do this article for months now, but you know how it is.. procrastination ^^

Nitrogen Deficiency is pretty tricky, during the vegetative stage and most of the flowering stage it’s definitely not a good thing, but by the end of the flowering stage it’s actually something you want going on.
In this article we’re going to cover each case so don’t worry 😉

Leaf mid way through nitrogen deficiency starting to curl up

What Is Nitrogen Deficiency?

As the name indicates this deficiency is the plant showing that it doesn’t have enough Nitrogen to grow. How does she solve the? By sucking it out of the older sections of the plant (aka lower leaves). This is why you see the leaves change color and crisp up.

If you’re seeing this don’t worry, Nitrogen Deficiency is one of the most common deficiencies that indoor growers of all levels cross. The fix is generally pretty straight forward.

How does the Marijuana use Nitrogen?

Nitrogen (N) is one of the 3 main vital elements to Marijuana (the 2 others being Potassium and Phosphorous).
Its usage is mainly present during the Vegetation Stage since its the major component of Chlorophyll, the compound used by plant for photosynthesis. It’s also one of the main components of Amino Acids, the building blocks of Proteins, making Nitrogen necessary for a plant to grow.

Since usages are mainly focused to vegetative stage tasks, the plant will basically stop in-taking Nitrogen once flower production has started, so you don’t want to get into Nitrogen Deficiency too early in the Flowering stage.

Here’s a recap of the usages

Usage of Nitrogen in each Stage of Life

 Stage of Life Usage of Nitrogen
Vegetation Stage
  • Production of new cells and enzymes
  • Needed for Chlorophyll production (green pigment/Photosynthesis)
  • Responsible for leaf and Stem Growth
Flowering Stage
  • Very low or no uptake from the roots
  • Growth of new top leaves the access to light isn’t sufficient.
  • Growth of small leaves near the flowers

How to spot Nitrogen Deficiency on Cannabis?

As most ways of spotting deficiencies with Weed the leaves of the plant is where you should be looking.
The most recognizable sign is the yellowing, crisping then falling of the leaves. We’ll cover this in 2 sections:

What are the signs of this deficiency on Marijuana?

  • The symptoms start at the bottom of the plant and move to the top.
    If this is not the case, you have another deficiency for sure, go back to the diagnostic steps.
  • From the tips, the leaves start to turn yellow. This will move inward until the leaf is fully yellow.
  • After this the leaf will start to become brown and crisp, again starting at the tips and moving inward.
  • By the end of the 2 steps above, maybe even before that, it’s very simple to remove the leaves.
    They basically just fall off.
    If this is not the case, you might have something else going on, such as light burn (article coming soon on that subject).

These are the main signs that your plant is suffering from Nitrogen deficiency. Now, I know it’s kind of hard to match words with symptoms so here’s the evolution of it in pictures 😉
As always, you can click on the images to get the full view.

Evolution of Nitrogen Deficiency

Leaf starting to turn yellowish

Early Signs of Deficiency

Leaf fully turned yellow

Leaf has fully turned yellow

Browning and curling leaf

Tip of leaf drying up and browning (dying)

Brown, crisp and dead leaves due to nitrogen deficiency

Leaves crispy and dead

How to solve Nitrogen Deficiency on Weed?

As we started saying in the first section on this page your action won’t be the same whether your plant is in the vegetative or flowering stage.
In order to be able to bring the answer to each stage we will divide this section into 3 parts:

Nitrogen Deficiency during the Vegetative Stage

During the vegetative stage the Marijuana plant intakes the most Nitrogen as she can, using it to grow new sections of the plant. As the plant grows so does her need for it.
If she cannot extract enough from the medium the plant will start pulling out the Nitrogen from the lower sections, that generally receive less light, in order to reuse it in the growth of the higher sections.

So it’s definitely not cool to be having Nitrogen Issues but you can easily recover, all you need to do is increase the nutrients in your next mix and you should see the spreading of the symptoms gradually stop.

Note that, as with most deficiencies, the affected leaves will not recover.

To sum up:

  • In your next watering increase the amount of Nitrogen provided (NP Solutions)
  • Keep the pH between 6.2 and 6.8 (check out our watering guide for more)
  • Keep an eye on your plant the following days, you should see the spreading stop.
  • Affected leaves will not recover
early signs of insufficient levels of nitrogen

Early signs of Deficiency

Nitrogen Deficiency during the early Flowering Stage

Once the plant has finished its vegetative growth, sometime during the stretch, she will naturally reduce (in some cases even stop) absorbing Nitrogen from the medium.
This makes Nitrogen issues a little more serious since you can lose a large amount of leaf mass.

What you can do is spray your plant with a water/nitrogen mix about 15 minutes before lights out. Depending on where you’re at in the flowering stage, your plant might absorb the Nitrogen through her leaves.
Be aware though, if you do this make sure it isn’t a long release solution.

The plant on the image on the right here had started the Nitrogen deficiency after the stretch giving her a real hard time to produce energy from photo-synthesis and develop her buds.. They were sweat but one of the smallest yields ever…
If you get caught in Nitrogen deficiency early on, definitely act on it!

To sum up:

  • Cannabis stops absorbing Nitrogen through her roots after the stretch.
  • Spraying the plant with a Nitrogen rich mix can help.
  • Buds with lower levels of Nitrogen will have a more refined taste although they won’t weigh as much.
All leaves of the plant turned yellow - very strong deficiency

Strong Nitrogen Deficiency half way through Flowering Stage

N.D at the end of the Flowering Stage

During the last 2/3 weeks of the flowering stage, while you’re flushing your plants, you want there to be this deficiency going on.
If you don’t do this your buds won’t have a very great taste, might sparkle a little but will weigh much more. Quality wise you’re really loosing a lot.

To sum up:

  • During the last weeks Nitrogen Deficiency is positive
  • Too much Nitrogen in the buds will ruin the taste of your harvest
  • Don’t forget to flush (water with no nutrients) during the 2 last weeks
positive deficiency nearing harvest time

Deficiency at the end of the flowering stage

Most Common Reasons of N.D

Coming soon

FAQ on this Deficiency

Further below we’ve grouped together all the questions we’ve seen often about Nitrogen Deficiency (ND).
If you don’t see what you’re looking for send us a email (contact in the top right) and we’ll get right back to you and add it to the site for others.
Here’s what we got so far:

  • Does Weed absorb it during the whole life cycle?
  • Is ND dangerous for your plant?
  • Don’t confuse with light burn!

Does Marijuana Absorb Nitrogen during her whole Life Cycle?

That is a big negative! Cannabis only absorbs this Nutrient during the vegetative stage and up to the stretch.
After this point the nutrient that will be brought up will be very low in Nitrogen. Spraying the plant with an enriched solution can help solve the issue, but it may be too late if you’re ways into the flowering stage.

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