Is't just that time of year. Â I use a product in a green bottle (forgot the brand) that you hook on your house. Â It supposedly has a mold inhibitor in it. Â I do notice the difference from when I just used outdoor bleach. 4951
I spray mine with some house cleaner from Lowes with a pump sprayer then power wash the mildew off.  But mine is on bricks.  Not sure about how to clean hardy plank? 4951
@donnatella: Â Nope, not Simple Green.... Â It is in a bright green bottle that comes with a hose attachment. Â The name just escapes me right now... 4951