If symptoms are localized to mostly mature leaf sets (those on stems already carrying blooms), see which one of the following deficiencies your plant may have.
Leaves lighter green to yellow, with random leaf spots. If soil is too acidic (pH 5.8 or less), apply lime (1/4 to 1/2 cup per bush). If pH is OK, fertilize with high nitrogen fertilizer (1 to 2 tablespoons per bush).
Leaves dark green developing dark red and purple colors, mainly within leaf (colors can also spread to outer edges). If soil is too acidic, apply lime. If pH is OK, fertilize with high-phosphorus fertilizer (20 percent), 1 to 2 tablespoons per bush.
Dead tissue, mainly at edges of leaves. If soil is too acidic, apply lime. If soil pH is OK, feed with 2 tablespoons per gallon of potassium nitrate.
Large areas of dead tissue at tips and between veins. Apply lime to correct pH. If pH is OK, then apply zinc chelate (1 teaspoon per bush).
Yellowing starting from center of leaf, with signs of dying tissue overlaying the affected parts. Apply Epsom salts, 1/2 cup sprinkled around the base of each bush.
If symptoms are localized to emerging foliage, use this page to determine the cause and treatment of the problem. Shown at right is an example of healthy emerging foliage, with normally purplish leaves on stems that do not yet have mature blooms.
Young leaves are hooked. Apply calcium nitrate (1 to 2 tablespoons per bush per week) until corrected.
Young leaves are light green at base and twisted. Apply 1 teaspoon Borax per bush.
Young leaves are permanently wilted with no chlorosis (yellowing). Apply copper sulfate (1/4 teaspoon per bush).
Leaves are light green with lighter-green veins. Apply soil sulfur (2 tablespoons per bush) or apply a fertilizer containing this element.
Leave are yellow with principal veins light green. Use iron chelate (1/4 teaspoon per bush) for immediate correction. Iron sulfate takes longer to act.