Composite decking is a great choice when compared to wood decks, mostly because it requires very low maintenance.
Once the fence or deck is constructed, it should not be neglected. The entire structure should be cleaned at least once a season with a deck cleaner to prevent mold & mildew. Exposure to constant moisture, and temperature fluctuations makes for a perfect environment for your deck to start looking mossy, no matter what material it is built out of.
If pressure washing the deck, ensure the pressure washer is no greater than 3000psi, as the strong water flow may leave gauges. Periodically cleaning your deck will always keep it looking nice.
When cleaning snow off of your deck, use a plastic shovel. A metal shovel may leave scratches on your deck boards. Calcium chloride may be used to melt the snow off of your deck if necessary.