What causes azalea leaves to be pale instead of lush and green? I have 2 large pink azalea bushes which have bloomed beautifully in May for 25 years but the leaves are pale. How can I get the foilage to look more darek green and lush? They are planted on the north side of the house near St. Louis, MO.
There are a couple of possible causes for the pale leaves on your azalea. If the pale green or yellowing is interveinal (that is, the veins are still green) it could be due to iron chlorosis from soil that has a pH that is too high. If that's the case, you should be able to correct it by acidifying the soil and/or applying iron chelate to the foliage.
If the pale coloration is a fine stippled pattern throughout the leaves, it's possible that your azaleas were attacked by lace bugs. These insects feed on the leaf undersides, leaving the top looking yellowish. Azalea bushes that are in the shade and that have plenty of moisture are less likely to be attacked. But you may need to spray for the insects beginning in early spring to prevent the damage. (The plants are seldom weakened by the lace bug feeding, but their appearance is affected.)