Know the Signs: Symptoms of Excess Iron in Plants

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Symptoms of Excess Iron in Plants
Symptoms of Excess Iron in Plants

Iron is an essential nutrient required by all living organisms, including plants. It plays a crucial role in photosynthesis, respiration, and many other metabolic processes. However, just like any other nutrient, too much iron can be harmful to plants.

Excess iron in the soil can lead to toxicity, causing damage to the roots and reducing crop yields.

As a plant lover, it’s important to keep an eye on your plant’s health; read on to find out the symptoms of excess iron in plants and what you can do to prevent it. You might also enjoy reading: How to reduce Iron in soil: A guide to healthier plants and better harvests.

1- Stunted Growth

One of the most common signs of excess iron in plants is stunted growth, where the roots may become brittle and thin, unable to absorb water and nutrients properly (Source: Frontiers)

In addition, the leaves may also become smaller and thinner, with a yellowish color. If you notice these signs, it is essential to test your soil for excess iron and other nutrient imbalances.

If your plant is not growing as quickly as it normally would, it could be a sign of too much iron in the soil. This is because excess iron can cause root damage, which in turn affects overall plant growth.

2- Chlorosis

Iron deficiency is one of the most common nutrients associated with chlorosis. Generally, Iron chlorosis starts on the younger or terminal leaves and works inward to the older ones (Source: University of Illinois Extension)

Chlorosis is a condition where the leaves of a plant turn yellow due to a lack of chlorophyll. However, it can also happen due to excess iron in the soil.

When there is too much iron, it can block the absorption of other essential nutrients, leading to malnutrition and chlorosis.

How to Prevent Chlorosis in Plants:

  • To prevent Chlorosis from occurring, it is essential to ensure that your soil pH is between 6.0 and 6.5, which allows for maximum uptake of nutrients.
  • Iron becomes more insoluble as the soil pH rises above 6.5 to 6.7. Most plants can absorb Iron as a free ion (Fe++) when the pH is between 5.0 and 6.5.
  • If the chlorosis is caused by soil compaction, you can fix it by improving soil drainage, aeration, tiling, and mulching.

3- Leaf Spotting

Another sign of excess iron in plants is leaf spotting. The spots may be brown, bronze, or yellow, and they usually form a ring around the edge of the leaf.

Leaf spotting generally occurs when there’s an accumulation of iron in the leaves, leading to oxidative stress and tissue damage. If you notice leaf spotting, it’s crucial to reduce the iron levels in the soil by adding organic matter and reducing the use of synthetic fertilizers.

Leaf discoloration is due to the fact that excess iron blocks the absorption of other nutrients, like magnesium and manganese, which in turn affects chlorophyll production.

How to Manage or Prevent Leaf Spotting (Source: University of Minnesota)

  • Rake up and destroy fallen leaves to avoid contamination 
  • Prune plants to improve light penetration and promote air circulation throughout the canopy.
  • Keep a 3- to 4-inch-deep layer of mulch around your plants.
  • Avoid fertilizing plants suffering from leaf spot diseases.

4- Reduced Yield

Excess iron can also reduce crop yields by damaging the roots and interfering with nutrient uptake. In severe cases, the plants may fail to produce any fruits or flowers, leading to total crop loss.

How to Improve Yield:

To prevent this, it’s essential to maintain a balanced soil pH, provide adequate drainage, and avoid over-fertilizing your plants.

5- Root Discoloration

If you notice that your plant’s roots have turned a rusty red color, it might be a strong sign of excess iron because iron oxidizes and turns the soil red in color.

As I mentioned earlier, Iron chlorosis often happens in alkaline soils (pH greater than 7.0); iron toxicity can also cause root damage, which prevents the plant from absorbing other essential nutrients. In other words, excess iron results in chemical reactions caused by a high level of soil’s pH, making the iron solid and unreachable to plant roots.

How to Manage Root Discoloration (Source: Utah State University)

  • The treatment for iron toxicity is to adjust fertilizer schedules to keep your soil’s pH between 6.0 and 6.5.

6- Brown Tips/Edges

If your plant’s leaves are turning brown around the edges or tips, it could be a sign of excess iron because excess iron can cause salt buildup, which can burn the tips of the leaves.

For example, excess salts can build up in the soil when you overfertilize, leading to brown leaf tips.

In addition to inconsistent watering, such as letting your plants dry out too long between waterings, improper fertilization will cause leaf edges and tips to turn brown (Source: Iowa State University)

To prevent brown tips/edges

  • Water and fertilize your plants appropriately.

7- Reduced Flower Production

Also, if your flowering plants are not producing as many blooms as usual, it could be due to excess iron. Excess iron can cause oxidative stress, which can damage flower buds and prevent them from blooming properly.

Excess or improperly timed fertilization can slow flowering and fruiting.

How To Prevent Reduced Flower Production:

  • Properly and timely fertilize to prevent reduced flower
  • Research has revealed it is best to apply fertilizer uniformly over an area rather than concentrating fertilizer in a hole (Source: North Carolina State University)
  • The most effective way of fertilizing a large space is with a fertilizer spreader or hand fertilization for home gardens.

Preventing Excess Iron Levels in Your Soil

To prevent excess iron levels in your soil, you can use several techniques.

What to read next:

Wrapping Up

Excess iron in plants can be detrimental to their growth and yield. I believe that knowing the symptoms of excess iron in plants can help you quickly identify any problems and take action to correct them.

By properly managing the amount of iron in your soil, you can ensure your plants are thriving and producing beautiful blooms.

I encourage you to ensure that your soil pH is optimal and avoid over-fertilizing; by doing so, you can help your plants thrive and ensure a bountiful harvest!


Hello friends, I am Altiné. I am SO excited you are here! I am the guy behind Plants Heaven is a blog that shares information about preparing, creating, and maintaining gardens in and out of your home, regardless of where you live. My goal is to help you learn to love gardening and reap the benefits that come with it. I am still learning; therefore, the information I share on this site may not always be “expert” advice or information. But, I do my VERY best to make sure the information shared on this blog is both accurate and helpful.

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