Iron is necessary for the production of chlorophyll, which makes the leaves green. Chlorosis is caused by the plant not being able to acquire the iron it needs, which causes the leaves of plants to turn yellow and then brown. However, this condition can be treated.

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Leaves Turning Yellow? Check for Iron Chlorosis

Iron chlorosis is a problem throughout most of the state of Kansas. And, it varies many locations. In the Master Gardener’s flowerbed in Goodland, which is in the western corner of the state, our pH here runs anywhere from 7 to 8 ½ on the scale. Plants are affected differently. You can see in these petunias, that they are starting to show signs of iron chlorosis.

Some plants aren’t affected as much. You can look up here and see some plants that aren’t affected. Beside them, in the same soil, is another plant that’s almost gone because of the iron chlorosis.

If you look at the leaves, you’ll see that the veins remain dark in the center, and the foliage turns to a light green. Healthy foliage is a darker green. This petunia is showing a lot of iron chlorosis.

It varies how plants react to it. There are some things that you can do to help the flowerbed. In annual flowerbeds, when you remove the foliage in the fall, you can work in some Canadian peat moss that has a low pH. That will help lower the pH, which makes the iron more available for the plants.

We also recommend soil testing every three years. That will tell you where you’re at with your pH. You can also work in some sulfur for your annual flowerbeds. You’ll know how much to add by looking at the results of the soil test. Work the sulfur into the flowerbed in the fall to help out next spring.

You can also fertilize with fertilizers that have some sulfur in them. There are several things you can do to combat the pH levels. Towards the end of the growing season, the plants are just running out of steam because of the iron chlorosis. But, you can work towards making it better next year.

This feature story prepared with Dana Belshe, Kansas State University Research and Extension Agent, Sunflower Extension District. For more information, visit your local county extension office or visit our website at

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