Iron is a micronutrient as only a small amount of it is needed for the Cannabis plant’s normal growth. To compare it with other nutrients, 1.5 pounds of iron is enough for an acre.

When it comes to nitrogen, which is a macronutrient, an amount of 80 to 200 pounds is needed for the same area. See the big difference?

What Can Cannabis Plant Benefit from Iron?

Iron serves numerous roles in a plant’s functions. It is a component of enzymes and proteins that are present during photosynthesis. 

It participates when chlorophyll is being manufactured. It’s also responsible for the structure, function, and maintenance of chloroplasts.

It has something to do with the process of respiration, which is the essential foundation of life. It contributes to pigmentation too.

It can do these things even though it’s not a mobile element. Marijuana plants can absorb in ferric ion form, and it’s also possible in organic form. 

Of course, it’s more effective in soluble form with a pH level of 5 to 6.5. The deficiency may occur when the pH level is out of the mentioned range. 

Signs of Iron Deficiency in Cannabis Plants

There are several nutrients given to marijuana plants, so signs of deficiency of a certain nutrient can be confusing. Iron deficiency can be misconstrued as a lack of manganese, nitrogen, or zinc. 

The signs of iron deficiency are so close to the lack of magnesium. But you have to take note that the newer, inner and upper leaves are affected when your plants need more iron.

In the case of magnesium deficiency, it affects older and lower leaves of the plant.

To avoid mixing things up, here are the signs that would tell you that your plant needs to be cured of iron deficiency.

Early Signs

The earliest symptom of plants that lack iron is the chlorosis of young leaves. Their color turns to a pale shade of yellow. However, the veins remained unchanged in a green hue. 

If these early signs are ignored, older leaves will soon be affected. To differentiate nutrient issues, search for the exact part of the foliage that became yellow first.

The deficiency of iron affects the younger leaves. Other nutrient deficiencies may begin with the middle portion of the bottom part of the plant.

Later Signs

The pale yellow color of young leaves will become brighter and will cover the whole leaf. This action will take effect slowly. 

Hence, it gives you time to be able to recognize the signs and apply a remedy. When the yellowing hue persists, the plants will be disabled to make food.

The yellow leaves will fall, and the plant’s growth will be halted. The formation of buds will also be minimal.

How to Handle Iron Deficiency

1. Putting pH in the Correct Range

A high level of pH at the roots is the common reason why iron deficiency occurs. This nutrient is locked up if the pH is too high that it reaches 7.0.

It usually takes place when the medium used is coco coir and soil. If the pH is too high, you have to flush it with pH’d water. 

It will eliminate any nutrient salt that may hinder the uptake of iron, and it will restore the proper level of pH.

Soil – 6.0 – 6.5

Hydro / coco coir – 5.5 – 6.5

2. Providing the Right Nutrients

Adding more iron is not a great response to iron deficiency. Most cultivators give plenty of iron to their plants, and there’s an ample amount of this nutrient in tap water.

There’s no need to worry about putting more iron if you started your cultivation with quality soil and Cannabis-friendly nutrients. Iron deficiency will likely to happen if the grower uses heavily filtered or reverse osmosis water. 

Iron was removed in the mentioned watering method. This deficiency starts when there are issues with other nutrients like magnesium, calcium, and excess copper. 

If you’ve checked that your PH level is correct, but you still suspect that your plants are experienced iron deficiency, simply flush them with ph’D water. If it’s on the schedule, you can add supplements like iron, calcium, and magnesium.

Marijuana plants love calcium and magnesium, and both of them work together with iron. A supplement that is a combination of calcium and magnesium can prevent his deficiency from occurring.

It’s compatible with coco coir, hydroponics, and soil. It is a supplement, but it also works great with growing Cannabis plants.

3. Caring for the Plant’s Roots

Root problems would also result in iron deficiency. It can happen when the plants are overwatered; even the pH level is right.

Proper watering routine contributes a lot to allow your plants to grow healthily. It can also minimize possible problems.

4. Recovery Phase

After doing all the necessary process of remedy, you can expect that your plants will be back to shape in a week or so. Some yellow leaves may not recover, but green, healthy ones will pop up.

Some Remedies

1. Iron Chelate

Utilizing iron chelate is a way of having your leaves return to its green, healthy state. It’s a temporary one as it only helps those iron-sprayed leaves to recover.

You can repeat spraying whenever there’s new sprouting.

2. Additives for Soil

The market offers various and excellent products that can help you stabilize the pH that is present in the soil. You decide on what’s suitable and convenient for you.

But you should flush first your growing medium before giving soil additives to your plants.

3. Compost

Compost can raise the level of pH to 0.1 and 0.2. It stabilizes the soil and enriches the amount of iron.

It creates better drainage for the plants to efficiently take up minerals. You can apply about three or four inches thick of compost and work it in the soil with six to twelve inches depth.

4. Elemental Sulfur

You have to wait for a couple of months to witness the positive outcome of elemental sulfur. But it’s all worth the wait as it can cure deficiency for good.

It lowers the pH level, and it makes iron readily available for Cannabis plants. Since it takes time to take effect, you can work it within 6 inches of the soil a year before the time of the next plantation.

It is the best precaution for iron deficiency.

5. Fertilizer

Nitrogen fertilizer can make iron more accessible, and it can lower the pH level too. The one that contains urea and ammonium sulfate works wonders in soil.

Growers should only give the recommended amount to their marijuana plants. 

Summary of the Causes of Iron Deficiency

1. Iron deficiency doesn’t happen too often.

2. Excess amount of calcium and bicarbonate from nutrient solution activates the immobilization of iron in the alkaline substrate.

3. Interaction with other cations caused by excess copper, manganese, and zinc can ignite deficiency.

4. Some organisms transform iron into ferrous oxide, which plants can’t uptake.

5. The excess of luminous intensity.

6. The root system gets weak due to numerous factors such as low temperature, poor drainage, no sufficient oxygen, etc.

If something is lacking, some things will be excessive too. So aside from iron deficiency, there’s also an excess of iron that can be related to deficiency as well. 

Cannabis growers should be worried about these two conditions.

Roots Uptake of Nutrients

It was already mentioned that iron has a role in photosynthesis and soil with a low pH will allow plants to absorb iron readily. Both iron and manganese share an essential role in a plant’s growth and development.

They compete for absorption. The abundant micronutrient will be more prevalent than the one with a lesser amount. The solution for this is having an equal ratio of manganese and iron, so they won’t overpower each other.

Toxicity from Iron

This is a rare circumstance, but some Cannabis plants would secrete acids from the roots. It then lowers the pH level. 

The plants can take too much iron, which leads to toxicity. The leaves will start to turn into stippling or to bronze.

A high amount of iron can create enzymes to control free radicals, so discoloration then exists. 

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