Stop yellow leaves on plants

The sudden appearance of yellow leaves on plants accustomed to acidic soils-such as azaleas, hydrangeas, and gardenias-could signal a drop in the plant’s iron intake or a shift in the ground’s pH above a comfortable 5.0 level. Either problem can be resolved by watering the soil around the afflicted plants once a week for three weeks with 1 cup of a solution made by mixing 2 tablespoons apple cider vinegar in 1 quart (1 liter) water.