If you've noticed your garden plants producing healthy green leaves in spring that turn yellow as the season progresses, your plants may be suffering from iron chlorosis. Iron chlorosis is a common problem in alkaline soils and is easily recognizable by interveinal chlorosis, which is characterized by yellow leaves with dark green veins. Iron is a nutrient needed in small amounts by plants and is plentiful in most Utah soils. Unfortunately, the high pH of our soils affects the availability of iron. In high pH soils (pH above 7), the iron rapidly forms solids and, therefore, is not available to plants. The best solution to iron chlorosis is to choose plants more tolerant of high pH soils and low iron. For existing landscape plants, there are several options, though these are only temporary solutions. • Apply sulfur or iron sulphate around plants that show signs of iron deficiency. This will temporarily lower the soil pH, making iron more readily available. • Apply iron chelates in spring to plants that showed signs of iron deficiency last year.
• Apply iron directly to the leaves (foliar application). All of these products can be purchased at a local garden store. To learn more about your garden soil, have your soil tested. Soil testing kits are available from the Utah State Extension office at 2001 South State St., Ste S-1200, Salt Lake City. For a minimal fee they will test soil for pH, major nutrients, organic matter, and texture, as well as make fertilizer recommendations.