I have a star jasmine in trouble. The leaves start out deep green but slowly turn yellow and, in time, red. It still flowers but doesn't look well. It's about 7 years old and this only happened in the last year. From all the literature, I can't figure out exactly what it might be. I've fed it and mulched but nothing works. Please HELP!
Hey Jossy, sometimes a general purpose fertiliser may just not do the job as it sounds like your plant is suffering from a mineral deficiency - either iron, zinc or manganese.
This can be caused by soil being too alkaline and easily remedied. An application of sulphur or addition of woody organic matter can help balance the pH and you can also spray on some foliar Chelates which will help adjust the balance of minerals.