I hope someone can help me save my hibiscus that is rapidly losing leaves and has maybe 10 left. Leaves are turning yellow literally overnight by the dozen and dropping off the plant. New leaves do grow but not fast enough to replace what is dropped. But the plants are blooming like crazy. I checked the pH (6-7), I keep the soil evenly moist, they are in full sun, and they've been fertilized regularly (once a month). I've had one of these shrubs for 2 years and this is a new problem. There are 2 plants in the ground within 6 feet of each other that are grown under the same exact conditions and are suffering the same exact problem. The only pest problem they've had is aphids, which I treat with soapy water. Could there be too much phosphate in the soil from all the soapy water dropping off the leaves and into the soil? Thanks for any help!

Lynne