Do you Have a Manganese Deficiency in your Cannabis Plants?

If you notice slow growth and yellowing between the veins of new leaves of your cannabis plants, you may have a manganese deficiency.

New growth is impacted and can turn to tan brown spots.

When your marijuana plants are lacking manganese, it can be hard to spot and at times may also be confused with an iron deficiency.  

The irony is that too much iron can cause the plants to lack manganese.

If you suspect your plants are lacking manganese check out some of the more signs below,

Signs of Manganese Deficiency

These are the sign of a manganese deficiency.

  • New leaf’s show yellowing between veins
  • Dead spots appear on severely damaged leaves
  • Dark green surrounding yellowing
  • Moves from top to bottom
  • Slow growth
  • Random spotting
  • Brown, tan spots
  • Yellow leaves (older) bottom
  • Leaves curl under

Why is manganese important to cannabis?

Manganese is required for photosynthesis.

The micro-nutrients aids in the uptake of nitrogen.

It also helps with the development of roots and for the plant immunity. According to ProMix.

In plants, manganese helps with pollen production, with assisting with pollen tube growth.

Pollen tubes can be translated into cannabis as the formation of trichomes.

Manganese is immobile and new leaf’s impacted first.


Causes of Manganese Deficiency

Here are the common reasons for your plants lacking manganese:

  • Lousy drainage grow medium such as soil.
  • Which leads to over watering
  • Having high PH levels
  • Growing outdoors, lacking manganese in the soil.
  • High PH soil above 6.5 (check your soil ph values )

You can also run into Manganese Lockout.

Manganese Lockout happens when the PH is above a certain level.

Causing the medium to become Alkaline for the roots.

This stop’s the uptake of manganese by your cannabis plants.

Here are some PH values to watch for if they are above these values:

When growing in soil: PH levels of 6.5 or higher

Hydro and Soilless Mediums: PH levels of 6.1 or higher.

How to Fix Manganese Deficiency

The best ways to fix manganese deficiency with marijuana is:


Dry out plants if your growing in soil (not entirely)


Flush plants with PH balanced water


Adjust the PH level in the soil or coco coir.


Correct the PH level of both your water/nutrients.

The optimal values should be in the following ranges:

Soil, 6.0 – 6.5 pH range. Hydro or coco coir, 5.5 – 6.2 pH range


Manganese chelate could be used if you don’t see results clear in a week.


Fix your drainage situation with more holes.


Signs of excessive amounts of manganese

Having too much manganese is rare to get when you’re using well-balanced nutrients for different stages of growth.

If you suspect, you have too much here are the signs,

  • Appears on older leaves 
  • Leaf perimeter and tips will start to die.

How to correct excess iron


Dry your plants out first.


Flush your plants. With PH balanced water.

Your plants will usually recover .


Get some proper nutrients to grow with.

Final thoughts


Yellowing between the veins

A manganese deficiency in your cannabis plants can happen.

By correcting you’re over the watering issue if there are any and adjusting the PH of your growing medium.

The issue should resolve in a week if not extra manganese were required to help your plants.

Also, remember most nutrients have some form of manganese in them.

Have you had manganese issue with your plants?

How did you recover?

Let me know in the comments.

Keep Growing my friends.

image credit: Image 

6 thoughts on “Do you Have a Manganese Deficiency in your Cannabis Plants?”

    • check to see the run off of your ph . If it is on the low side them water your plants with a slightly higher ph range for soil instead of say 6.2 , try for 6.8. and over the next few watering’s with nutes it should raise the ph of the soil to the happy range again. or vice versa if the h is to hi try watering with nutes of a lower ph to bring the soil ph it back down.

    • Cal-mag had magnesium in it, if your think you have a manganese issue not sure if it would help it. But if you are not using cal-mag it doesn’t hurt to use it it should benefits your plants


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