manganese deficiency marijuana

Manganese Deficiency

Problem: Leaves may become yellow in between the veins, with mottled brown spots on the affected leaves. These brown dead patches may spread and eventually kill the leaf. Leaves may also shred and fall apart.

Overall growth of the marijuana plant may be stunted. With a manganese deficiency, the yellowing will begin at the base of the leaves and move outwards towards the tips.

Solution for Manganese Deficiency in Cannabis

Your plant may also exhibit signs of a manganese deficiency if the pH is too high, or if the plant is getting too much iron.

Please note: After a manganese deficiency is cleared up, the problem (brown spots and yellowing leaves) will stop spreading to other growth usually within a week. Please note that leaves which have been damaged by a manganese deficiency will probably not recover or turn green, so you want to pay attention to other growth for signs of recovery.

  • In soil, manganese is best absorbed by the roots in the 6.0 – 7.0 pH range (some growers recommend keeping the pH slightly lower, from 6.0 – 6.5, if you suspect a manganese deficiency in particular)
  • In hydro, manganese is best absorbed by the roots in the 5.5 – 6.0 pH range (in hydro, it’s generally recommended to keep the pH between 5.5 – 6.5, but manganese specifically tends to be best absorbed below 6.0)

If you suspect your growing cannabis plant has a manganese deficiency, flush your system with clean, pH’d water that contains a regular dose of cannabis-friendly nutrients that includes manganese. This will remove any extra iron or nutrient salts that may be affected the uptake of manganese, it will help restore pH to the proper levels, and will supply the plant with any missing nutrients.

You are looking to avoid higher pH ranges, as this is where manganese deficiencies are most likely to occur.

If you cannot get rid of your manganese deficiency, please consult our 7-Step Cure to 99% of Cannabis Growing Problems

Plant Symptoms

  • Bronze or brown patches
  • Brown or slimy roots
  • Brown or yellow leaf tips/edges
  • Buds dying
  • Buds look odd
  • Bugs are visible
  • Curling or clawing leaves
  • Dark leaves
  • Drooping plant
  • Holes in leaves
  • Mold or powder
  • Pink or purple on leaves
  • Red stems
  • Shiny or smooth leaves
  • Spots or markings
  • Twisted growth
  • Webbing
  • Wilting leaves
  • Yellow between leaf veins
  • Yellow leaves

This page is part of our Plant Doctor series. You can use our tool to filter by symptom and help diagnose your plant.

Manganese deficiency can cause cannabis leaves to become yellow in between the veins, with mottled brown spots on the affected leaves. Learn how to treat it!

How To Identify And Treat Manganese Deficiency In Your Cannabis Crop

Published : Sep 18, 2017
Categories : Cannabis cultivation

Manganese is a vital mineral that is needed by plants to carry out numerous physiological functions. It plays an important role in photosynthesis, among other processes. Learn how to identify manganese deficiencies in order to prevent any loss to your crop’s yield.

Growing cannabis is a science in and of itself and requires a great deal of attention and preparation when attempting to cultivate buds of the utmost quality and quantity. The correct watering schedule, the right amount of light, good airflow, and dialled-in humidity and temperature all need to be considered when aiming to harvest a premium crop. Another key factor to pay attention to is nutrition. Cannabis plants require an array of nutrients that facilitate many different physiological functions that keep plants alive and thriving. One of these vital nutrients is manganese.


Manganese is a highly beneficial micro-nutrient that plants require for proper growth. Many processes in plants are dependent upon the presence of adequate levels of manganese. One of these is photosynthesis, which is absolutely critical to the growth and vibrancy of a cannabis crop.

Photosynthesis is the process of plants converting light into energy. Specifically, manganese serves in the formation of chloroplasts. These cells hold chlorophyll molecules and are responsible for converting light into sugars that are used by plant cells. A lack of manganese may result in a decrease in soluble sugar concentrations in different parts of the plant. This situation can then result in a reduced yield.

Manganese also helps to elevate the stress tolerance of cannabis plants. Many stressors plants experience come in the form of oxidative stress. Manganese is a mineral required by superoxide dismutase enzymes, which are responsible for the detoxification of free radicals. Adequate levels of manganese contribute to a higher tolerance toward external stressors, such as drought stress and cold temperatures.


Because of the important role that manganese plays in achieving optimal yields, it is important to identify the symptoms of deficiency quickly in order to return everything to normal as soon as possible.

Manganese deficiency symptoms manifest in different ways, including colour changes in the leaves. Leaves will begin to turn more pale in hue. New and older, lower leaves will begin to turn yellow. Yellowing will also occur between the veins of the leaves. The veins themselves will remain green. Brown or dark spots will also occur of the surface of leaves, as well as a mottling pattern. These dark spots will eventually spread and result in the death of leaves, which may end up falling apart altogether. Growth of leaves will also slow. The overall development of plants will begin to degrade.


If your cannabis crop is experiencing a manganese deficiency, you can flush plants clean using pH-balanced water that contains a normal dose of cannabis nutrients, including manganese. This process will remove any excess iron or salts that are inhibiting the uptake of manganese. It will also help to restore the pH to appropriate levels; a pH that is too high may cause manganese deficiency to occur via nutrient lockout. This can happen even when adequate levels of manganese are contained in the substrate. Once the pH is optimised and the proper concentration of manganese is restored, new leaves should appear healthy; affected leaves may not recover.

How To Spot And Treat Calcium Defiencies In Cannabis Plants

Manganese plays an important role in several vital physiological functions within cannabis plants. Learn how to identify and solve manganese deficiencies.