The leaves are yellow and I don't know what to do!

This is one of the most commonly asked questions concerning plants grown in high alkaline soils such as ours. Before the problem can be solved, there are a few things one must know.

Yellowing leaves could be the symptoms of a couple of problems. If the entire leaf is yellow, the problem could be nitrogen. In severe cases of iron deficiency, the entire leaf could be yellow, too.

The way to determine whether it is iron or nitrogen is by looking at the location of the yellowing leaves. Iron deficiency occurs on the new growth, toward the tips. Nitrogen occurs from the bottom of the plant on the old growth.

The symptoms of iron deficiency, also known as iron chlorosis, appear in the leaves as green veins and yellow leaf tissue. If the deficiency is severe, the entire leaf may become yellow. Lastly, brown edges may begin to show up. Also in severe cases, chlorosis can progress to older growth in the plant.

Iron chlorosis is found where soils are highly alkaline. The high pH of the soil ties up the iron in the soil, making it unavailable to the plants. Iron is required for the formation of chlorophyll in plant cells and serves as an activator for respiration and photosynthesis. High soil temperatures and high light intensity can also increase problems with iron chlorosis.  

Applying chelated iron is the best solution and last the longest. There are several formulations of chelated iron. The type of chelating agent recommended depends mainly on the pH value of the soil. In soil application EDDHA are preferable chelating agents for ensuring iron availability in alkaline soils.  It is the only iron we have found to be effective in our soil.  Chelated irons are more expensive but work better and last much longer. The powder form you mix with water is the most common. Read the label carefully before apply any product to your lawn or plants.

Apply iron products at the drip line of trees and shrubs. This is the area that plants take up nutrients and water from their roots. Always avoid getting any type of iron product on sidewalks, patios, driveways or brick. Residue from these products will leave stains that are difficult, if not impossible to remove.

Visit the Garden Center at Pinehurst Floral & Greenhouse for all your gardening needs.