I live in Zone 8 with Plumbago auriculata in several places - full sun to partial shade. The yard has an irrigation system with sandy soil with a small amount of clay. The way the drainage is the soil stays moist most of the time. The plants looked great at first. Now 4 months later many leaves have fallen off and there are few blooms. The temperature was ranging from 60-90 degrees F when it started to occur. Now the temp is 38-75 F. The leaves are pale green. Osmocote was placed under the plants initially. They have received Miracle Grow maybe 3 times. Should I have trimmed them back to stimulate growth? Have I washed all of the nutrients out of the soil? What should I do?