You are hereNitrogen Deficiency

Nitrogen Deficiency


Problem:  A cannabis nitrogen deficiency will cause the older, lower leaves on your plant to turn yellow, wilt away and eventually die.

The yellow leaves of a nitrogen deficiency may show signs of brown, and they will usually become soft and sort of "fold" in, before turning crispy and falling off on their own.

Picture by m&m - Cannabis plant with nitrogen deficiency - older leaves are turning yellow and falling off

If the yellowing leaves are at the top of your plant or the yellow leaves are mosty new growth, then you probably don't have a nitrogen deficiency. Nitrogen deficiencies always affect the oldest, lowest leaves first.

Nitrogen is a mobile nutrient, which means it can move throughout the plant as needed. Cannabis needs nitrogen to keep leaves green and make energy from light. All new leaves get plenty of nitrogen to make them green and help with photosynthesis. The leaves that get the most light are the newest, youngest leaves, so the plant "wants" to give those leaves priority for getting light.

If new leaves aren't getting enough nitrogen, the plant will start to "steal" nitrogen from the older, lower leaves, so that it can give it to newer leaves. This is what causes the yellowing and wilting of a nitrogen deficiency.

Cannabis nitrogen deficiency - Closeup of a yellow leaf from the bottom of the plant

It's relatively normal for your cannabis plant's leaves to start turning yellow towards the end of your flowering cycle as the plant becomes nitrogen deficient while creating buds.

However, if your cannabis plant is losing lower leaves fast due to yellowing (if yellowing and dying leaves is "climbing" up the plant from the bottom), especially in the vegetative stage before plant is making buds, you have a problem that you will need to fix as soon as possible.

You don't want a nitrogen deficiency in the vegetative stage!

A cannabis nitrogen deficiency should be avoided in the cannabis vegetative stage

If you notice your lower cannabis leaves turning yellow in the vegetative stage or in the beginning part of the flowering stage, your plant may be experiencing a nitrogen deficiency which will need to be treated.

It is not good if your cannabis plant is showing signs of an advanced nitrogen deificiency while still in the vegetative stage. It's normal to lose a few yellow leaves off the bottom of your plant here and there, especially with very big plants. But if you are losing a significant amount of yellow leaves, and the yellowing seems to be moving up the plant quickly, then you have a problem.

Cannabis nitrogen deficiency - yellow leaves are piling at the bottom of the plant

The first cannabis plant pictured below is showing signs of nitrogen deficiency late in flowering; nitrogen deficiency in late flowering is completely normal and even desired. The last picture is an infographic about nitrogen and your marijuana plant.

The signs of nitrogen deficiency (yellowing of leaves) in older, lower leaves is normal towards the end of the flowering cycleInformation about nitrogen and your cannabis plant

It's normal for plants to show signs of a nitrogen deficiency as the plant gets close to harvest. This is actually a good thing! Too much nitrogen can actually prevent proper budding, and can reduce the overall taste and smell of your plant. This is why all "bloom" and flowering nutrient formulas are relatively low in nitrogen.

So don't sweat it if you see your cannabis show some signs of nitrogen deficiency late in the flowering stage! Relatively low levels of nitrogen in the late flowering stage helps promote proper cannabis bud development and will increase your yields!

Don't worry about yellow leaves close to harvest!

It's normal to see yellow leaves late in the cannabis flowering stage

Solution: You can find many pre-mixed nutrients from the store which contain nitrogen or you could use nitrate of soda or organic fertilizer which are both good sources of nitrogen. In fact almost all plant nutrients of any kind will include nitrogen. If you haven't been providing any nutrient to your plants, try supplementing your regular nutrients with a bit more nitrogen and see if the plant starts recovering.

If you've already been using nutrients, then you probably don't have a nitrogen deficiency. If you're seeing the signs of spreading nitrogen deficiency even a week or two giving nitrogen to your plants through nutrients, then you need to figure out what else is causing the yellowing so you can stop it.

More About Nitrogen and Your Marijuana Plants

Sometimes you can get the signs of a cannabis nitrogen deficiency if the pH at the plant root zone is too low, even if the nitrogen is there. This is because when the pH at the roots is not right, your plant roots can't properly absorb nutrients. If you aren't sure about your root pH, learn more about pH & growing cannabis plants here.

Nitrogen is especially important during the vegetative stage of your cannabis plants. As your plants start flowering, they will need lower amounts of nitrogen.

See the nutrient numbers listed on the front?Nitrogen is one of the 3 nutrients that is included in almost every kind of plant food.

When looking at plant nutrients, you'll almost always see 3 numbers listed, like 3-12-6 or 5-10-5. These numbers represent the percentage of Nitrogen (N), Phosphorous (P) and Potassium (K) contained in the bottle. Just about all plant life on Earth needs these 3 elements to grow.

The very first number, "3" in the case of the picture to the right, always displays the proportion of nitrogen in this nutrient bottle compared to the other 2 nutrients (Phosphorus and Potassium respectively).

The reason nitrogen is in all plant nutrient formulations is because it's vital to plant processes. 

Note: During the last few weeks before harvest, marijuana plants starts pulling all the remaining nitrogen from her leaves as part of the bud-making process. This causes yellowing leaves starting towards the bottom of the plant. This is part of the natural flowering process and you don't need to fight it.You may notice that marijuana leaves are yellowing in almost all pictures of marijuana plants with big buds that are close to harvest. You tend to get smaller yields from nitrogen-toxic plants with dark green leaves at harvest.

Remember: It's Normal For Marijuana Leaves To Start Turning Yellow As Harvest Time Approaches

Marijuana plant ready for harvest, notice the yellowing leavess, which is a natural part of the ripening processIt's common for leaves to turn yellow towards the end of the flowering stage, no need to fight it!

Occassionally a nitrogen toxicity is mistake for a deficiency. Could your plant actually be nitrogen toxic? (pictured below)

This picture shows a Nitrogen Toxicity

Nitrogen toxicity

 

Picture: 
Cannabis Nitrogen Deficiency - Older leaves turning yellow  - GrowWeedEasy.com
Big Symptom Picture: 
Leaf Color: 
Pale Color Leaves
Yellow Leaves - Lower, older leaves
Yellowing Between Veins
Leaf Symptoms: 
Lower Leaves / Older Growth Affected
Yellowing Between Veins
Old Leaves Dropping Off
Wilting / Drooping
Plant Symptoms: 
Old Leaves Dropping Off