Spider Mites

The most likely cause of damage that looks like this on many plants is spider mites. They are sucking insects and cause this white mottled stippling on foliage when a plant is typically stressed. These critters aren’t really spiders although they are related to them. They are very hard to see, but the underside of infested foliage often looks dusty, sticky, and vaguely web-like and dirty. You can read more about spider mites and how to control them here: http://bit.ly/1pJ46WX You can also go to your local garden center and ask for an organic control for spider mites and then use the product according to directions but at thi point in the season, just compost it. No point in wasting money. Marigolds should be grown outside not indoors.