Sydney weather in March is perfect for turning your sails green. Rain, hot and humid.
You will be amazed at how fast those green lines of mould will appear on your nice white and expensive furled headsail.
Even sailing regularly is no guarantee of a mould free sail, the only thing that works is cleaning, once a year is the maximum time between cleans.
My own sails are used every week, yet even I find black spots of mould appearing, a yearly clean though has stopped it from becoming an issue.
Here is a recent picture of a sail before cleaning, I suspect that there was not much sailing going on here. Luckily this sail was sailkoted from new and has cleaned up looking that way again.