My Lily Pilly hedge that has been planted about two years is really yellow in colour and not growing. Some of the plants that were looking ok are now turning yellow. hedge on drippers with regular water.
It sounds like you plant maybe deficient of trace elements - but that may not mean that there just are not any in the soil, but that the plant cannot gain access to them. A good way to adjust this is to add compost to the soil, this acts as a tonic, encouraging the soil to release its load of elements. Then you can fertilise it (with a native formulation low in phosphorous) and the plant will be more able to draw them up. Native fertilisers generally contain plenty of nitrogen and that in itself is a good 'greener' of plants.