Help please. I have a hedge of 22 dwarf Brunfelsia. The leaves are yellow with some showing the brown veins through. They appeared OK during summer, but fade to yellow in winter. I was told to give them Sulphate of Amonia to 'green them up', but to no avail. Should I be giving them Aluminum Sulphate which is for acid loving plants. They have been in almost 2 years and I have only had about 6 flowers in total.