How to Fix Iron Deficiency In Plants

One of the most essential micronutrients for plants is iron. Iron is crucial for the metabolic processes including photosynthesis, respiration and DNA synthesis. Iron is also important for the activation of numerous metabolic, biochemical and physiological pathways, the electron transport chain and many biological functions. Iron is required for maintaining both the function and structure of chloroplast.
What Happens to a Plant with Iron Deficiency?
Iron is required for a plant to produce chlorophyll. This is what provides the plant with a healthy green coloration and oxygen. This is the reason an iron deficiency in plants results in sickly yellow leaves. Without iron, the enzyme function is impacted, affecting the health and growth of the plant. To maintain health, oxygen must be moved throughout the plant. An iron deficiency affects the quality of the plant causing:
- Improper formation
- Chlorosis in the new leaves
- Leaves turn a sickly yellow
Plant Iron Deficiency Symptoms
An iron deficiency affects the inner, upper and new leaves of the plant. If the leaves are severely damaged, recovery is often impossible. Intervenial chlorosis occurs resulting in pale leaf veins. Unless the iron deficiency is severe there is no physical deformity. Angular chronic lesions often appear on the leaves in severe cases, with new leaf growth stunted and white.
- New leaf growth is initially so yellow it appears almost white
- Inner, upper and new leaves are affected
- The development of chronic lesions
- Leaf veins become pale
Possible Confusion with Other Symptoms
- Micronutrient deficiencies including manganese are mistaken for an iron deficiency
- Leaves turn yellow from light stress or burn
- A nitrogen deficiency causes the older leaves to become yellow
- Leaves yellow due to a sulfur deficiency
- Upper leaves yellow when there is a zinc deficiency
What Causes an Iron Deficiency?

The most common reason for an iron deficiency in plants is a pH issue or a stressful environment. Chlorosis can result from diseased roots and overwatering. The plant is then unable to efficiently absorb nutrients including essential iron. If the pH level is incorrect for the growing medium, an iron deficiency can result. The most common issues include:
- The pH of the soil is too high
- There is too much clay in the soil
- The soil is too wet or compacted
- The soil contains excess phosphorus
- Diseased roots
- Overwatering
How to Fix an Iron Deficiency in Plants
You need to be patient because iron moves slowly within the plant. If the damage was extensive, do not be surprised if the yellow leaves fail to recover. When new leaves are growing in green, there is no longer an iron deficiency. The best treatments include:
- Rectifying environmental stressors
- Lower pH
- Flush with pH water
- Provide plants with the correct nutrients
- Use soil of the highest quality
- Eliminate any issues with copper, magnesium and calcium
- Use a supplement containing iron, magnesium and calcium
- Make certain the roots are taken care of properly
- Carefully watch the plants for about one week
If the iron deficiency in plants resulted from stressful conditions, recovery generally occurs once the stress is resolved. When the pH level at the roots is high, the iron can become locked at too high of a level. To correct the deficiency, the pH must be below 7.0. This issue is more common in coco coir or soil as opposed to hydro. Flushing the system using pH water will help restore the pH and eliminate nutrient salts.

If you live in an area where there is not enough iron in the water, you need to use soil of the highest quality to ensure the plants have enough iron. The two types of water often responsible for an iron deficiency in cannabis plants are RO and heavily filtered. These types of water do not contain any iron. An iron deficiency can also be triggered when there are issues with magnesium, calcium or excess copper.
Correcting the issues with other minerals can correct an iron deficiency. These three minerals work together closely to help ensure the health of the plant. If the levels of any of them are off, the plants can suffer from an iron deficiency. If you are unable to find a supplement containing all three, make certain it has calcium and magnesium. This combination can prevent nutrient deficiencies in the plant.
When flushing the plants with regularly scheduled nutrients, use pH water. This type of product is effective for several growing methods including soil, coco coir and hydro. When there is an iron deficiency, there is most likely a deficiency of magnesium as well. One of the first areas of the plant affected by an iron deficiency is the roots.
Even when there is more than enough iron and the pH level is ideal, overwatering the plants can cause issues with the roots leading to an iron deficiency. Make certain the plants receive the appropriate amount of water to help ensure healthy growth and to eliminate numerous issues. Once the issue has been found and treated, watch the plants for approximately one week.
How Long Does It Take for a Plant to Recover from an Iron Deficiency?
If the iron deficiency was caused by a stressful environment, the issue may resolve itself once the stress is no longer a factor. If the treatment is not provided quickly enough, the plants will most likely die. Even though this deficiency spreads slowly, the health of the plants can be destroyed. Provided the issue is caught early, the plants can recover in as little as one week.