ChlorosisAt first glance, the meadow rue leaves at right might look fine. But see how the veins are still green and the rest of the leaf is beginning to turn yellow? That’s the early sign of chlorosis, a lack of iron or manganese. It’s caused by planting an acid-loving plant in alkaline conditions.
Iron and magnesium are probably in the soil, but the plant needs a lower pH to create a chemical reaction so its roots can absorb them. This lack of nutrients causes a lack of green chlorophyll in the leaf, which means it’s not producing food for the plant. Over several seasons of chlorosis, the plant weakens and can even die.
An easy way to lower the pH is to sprinkle dry Epsom salts right on the soil (1?4 to 1?2 cup per 10 square ft.) around the plant. This can be done once, at any time of the year.