Nutrient Basics - Iron

Iron is an important component of some plant enzymes so while it is needed in small amounts, if it is deficinet you will not gave the best growth you can bet.

With an iron (Fe) deficiency like all movable nutrient deficiencies you will notice the change at the top of the plant as it works its way down. With an Iron deficiency look for the leaves to turn yellow but retain green veins. Shoots may die back and fruit may be discolored.

Causes of iron deficines are alkaline soil, (i.e. basic sols that are way above 7.0), applying too much phosphorus, over watering *The number one problem people have when E-mailing me*, excessive soluble salts, inadequate drainage. The good news, this is easily corrected by adding an iron supplement with the next watering.

Good growers know iron is unavailable to plants when the pH of the water or soil is too high. If iron appears to be deficient, lower the pH to about 6.5 (for rockwool, about 5.7), and check that you're not adding too much phosphorus, which as I said above can lock up iron. Use iron that's chelated for maximum availability. Read your fertilizer's ingredients - chelated iron might read something like "iron EDTA". Keep in mind too much iron without adding enough P can cause a P-deficiency.

You should also know that when adding iron to the solution, it is often necessary to not use fertilizer for that watering. Iron has a tendency of reacting with many of the components of fertilizer solutions, and will cause nutrient lockup to occur. Read the labels of both the iron supplement and the fertilizer you are using before you attempt to combine the two.

Iron Toxicity is rare but could cause brown spots on leaf surface.

Good Growing,
Dr. E.R. Myers

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