Rose of Sharon, or desert rose, is a flowering shrub notable for its long summer blooming period and its tolerance of a wide variety of climate and soil conditions. It thrives in well-draining soil but can quickly go down hill when forced to grow in poor-draining soils such as heavy clay. It's relatively drought tolerant and when mature requires little supplemental irrigation unless growing in very dry climes or during extended periods of drought. Correcting over-watering and its symptoms can be simple, but plant relocation is necessary when it has been planted in poor-draining soil.
Refrain from watering for a period of at least 10 days to three weeks to allow the excess moisture in the soil to dissipate. Water infrequently but deeply thereafter to keep the soil just lightly moist to the touch at all times when feeling a few inches down in the soil.
Correct for iron chlorosis caused by over-watering by amending the soil via top dressing with ferrous sulfate or an iron chelate product according to the package label directions. This will raise the iron in the soil in ways that the rose of Sharon can metabolize and will help to re-green and strengthen the foliage.
Relocate a rose of Sharon when it is planted in an area that has incompatible soil that drains poorly to fast-draining but nutrient-rich soil.