Cleaning artificial plants

My artificial plants are starting to turn black. I've tried to clean them and I have not been able to get the black off. Any suggestions? Is it ok to boil them without ruining them?

You may want to try using a nylon mesh to rub off the black algae. If you remove the plastic plants, chlorine or a strong vinegar solution will kill the stuff, but you will still need to do some rubbing and lots of rinsing. A plastic plant cleaning solution is also available on the market, but after reading the ingredients and precautions i decided to not use it. Probably i was being too cautious.

Like any kind of mold or algae, that black stuff needs a food source. The choice is to reduce the food source or add some fast growing live plants to use up the food source.