From the city of Monrovia's website:
Place your Christmas tree curbside on your regular trash collection day beginning December 26, 2012 through January 11, 2013. Please remove all ornaments, tinsel, plastic bags, nails, lights, and plastic or metal stands; otherwise, trees will not be collected. Flocked and fire retardant coated trees will be accepted. After January 11, trim branches and place in the green materials barrel. Reminder: trash collection service will be delaye one day due to the holidays. Click here for more info or call Public Works at (626) 932-5553.