Correcting Yellow Plants Timing is Critical

Q. I was told I need chelated iron for my roses. So, per instructions, I added the granulated type today. My question is, how often do I do this? They do not mention this on the label, just the dosage.

A. Chelated iron means the iron is “captured” by a chemical, called a chelate, that protects it. As long as the iron is protected, it can be used by the plant. Once the iron is “let go”, it is no longer protected. In our soils and water, if left unprotected the iron can no longer be used by the plant.

Iron EDDHA chelate for applying to the soil.
5 pound bag.

            You must have mentioned that your rose bushes were yellowing to get this kind of advice.  If the person helping you is knowledgeable, they would ask if the yellow leaves were on the ends of branches (new leaves) or further inside the plant on older leaves.  If this is an iron problem, the yellowing would be on the newer leaves.  If yellowing is on older leaves, it is a different problem.

            There are two methods of correcting yellow leaves because of iron problems.  One method is to apply chelated iron to the soil.  The other method that is to spray chelated iron, mixed with water, on the leaves.

            Timing, or when to apply the chelated iron, is critical depending on the method.  Chelated iron must be applied to soils in the very early spring before, or as new growth is emerging. 

            Applying chelated iron to the soil is the most effective way of correcting plants with yellow leaves because it only requires a single application.

Iron EDDHA chelate for applying to the soil
in 1 pound container

Iron chelate for mixing with water and spraying on the leaves

            The most effective chelated iron to apply to soils contains the chelate “EDDHA” in the ingredients. The more EDDHA iron on the label, the more effective it is.

            At this time of year, or any time after early spring, chelated iron must be sprayed on the leaves to be effective.  Applying it to the soil will not work. Unlike soil applications which are required only once in the spring, spraying iron on the leaves requires multiple applications for most trees and shrubs.  Applications to the leaves may be required four or five times, a few days apart, to get a decent green color again.

            The label may not tell you so but always use distilled or reverse osmosis water when mixing chelated iron to make a foliar spray. Our water is very alkaline and reduce the effectiveness of the iron chelate.

            Also, use 1 teaspoon per quart of spray of a mild liquid detergent such as Castile soap mixed into the solution as the last ingredient. Liquid detergents help move the chelated iron through the waxy leaf surface and inside the plant.